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Up in the mountains, mother nature can be harsh.
Weather varies and can effect classes with snow days.
Cold and snow in winter Not and humid in summer
Its typical Pennsylvania weather. Hot in the summer, cold in the winter.
It is generally very cold since we're up near the mountains. I'm not used to the harsh climate but you become used to it.
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LaSalle Thompson III (Tank)
Position: Center ▪ Shoots: Right
Height: 6-10 ▪ Weight: 245 lbs.
Born: June 23, 1961 in Cincinnati, Ohio
High School: Withrow in Cincinnati, Ohio
College: University of Texas at Austin
Draft: Kansas City Kings, 1st round (5th pick, 5th overall), 1982 NBA Draft
NBA Debut: November 20, 1982
Other Pages: College Basketball Stats
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subset: commoncrawl


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Parkfield is a picturesque hamlet secluded on the central coast of California. 25 miles northeast of Paso Robles and surrounded by the best of California's natural beauty. Parkfield's clean air, warm nights, and idyllic setting mesh effortlessly with true American music: bluegrass.
Every Mother's Day weekend this quiet town's population leaps from a mere 18 to over a thousand bluegrass pickers, pluckers and fun-loving fans. For nearly 2 decades music fans have savored the natural beauty and peaceful ambiance of the Parkfield Bluegrass Festival. Nature's soothing sights and sounds combine with the soulful, high lonesome sound of bluegrass music for an experience that is unique, to say the least.
At the Parkfield Bluegrass Festival live bands play all day on a cozy stage and at night fans enjoy late night sets in the Parkfield Cafe.
Meanwhile back in the campgrounds there are jam sessions galore. The festival also offers several workshops on a variety of instruments as well as a music camp for kids.
This Mother's Day weekend will find Parkfield once more transformed into bluegrass nirvana. We hope to see you there!
This year we are very excited to present QUAKE Radio that will be broadcasting the happenings at Parkfield Bluegrass Festival! Tune in May 5th-8th! Be sure to bring a portable radio and tune in to QUAKE Radio!
NOTICE – Online and Mail-in Ticket Sale is Closed
Online & Mail order ticket sales have closed, but don't worry, tickets are still available.
All tickets are now being sold only at the main gate.
Please come to Parkfield & purchase with cash, check or Visa/MC.
UPCOMING EVENT – May 6th, Friday, 10PM
During the annual Parkfield Bluegrass Festival, come join us for a Barn Dance with Evie Ladin calling, and live music from her band Keith Terry & Erik Pearson w/ Special Guests. Friday, May6th, 2016 at 10 PM at the Parkfield Community Center. No experience necessary, all dances taught. This is not something you want to miss. Get up and dance!


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Why do people make such big deals at certain body parts? Why so much self hatred?
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Senior Member
Join Date: Nov 2011
Posts: 620
Originally Posted by
Kevin, that was a hell of a post. You're a good egg.
I agree wholeheartedly with this.
ColorsWolf, I don't know you well enough but from what I've read on this thread, maybe it's possible that you have a little more to do to free yourself from your old, aggressive patterns of thought and behaviour? You have demanded several times that people read exactly what you say and have several times seemed frustrated and angry when your meaning has not been understood.
It comes across as quite controlling which is kind of the opposite of how you wish to be. Change isn't easy for anybody and maybe it is worth thinking about and considering if you have more work to do to free yourself from the old you.
I did notice that you had revised your opinion on 'wild animals.' I'm interested to know what sorts of wild animals you have heard about interacting with humans and under what circumstances?
Oh - and one final thing. This video is very much in line with my view on why so many humans have such hatred for their own bodies. I think that the media plays a much bigger part in it than any sort of worry about nudity being morally wrong.
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U.S. Customs and Border Protection has created a dedicated team to monitor violations of coastwise shipping rules as supporters tout the Jones Act's homeland security benefits.
Major freight railroads in the United States employed 152,426 workers as of the middle of June 2016, down 0.2 percent from the previous month and 11.55 percent year-over-year, according to data from the Surface Transportation Board.
The 8,530-TEU CSCL container vessel Xin Fei Zhou scraped its side against the wall of one of the recently inaugurated locks of the important Central American waterway, according to a report from the Associated Press.
Registration takes less than 1 minute.
The U.S. Department of Transportation is looking into how delays at ports and other loading and unloading facilities may be affecting driver compliance with hours-of-service rules designed to increase safety.
Former Macy's distribution center manager Rudy Rampertab pleaded guilty in the U.S. District Court in Cincinnati to one count each of mail fraud and money laundering.
Claudio Bozzo, chief operating officer of liner carrier Mediterranean Shipping Company, joins the World Shipping Council board.


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BulletProofBaby.net sells a baby stroller that is touted as being 100% bullet proof, an accolade reserved for products such as swat team body armor and military tanks. It even stops Armor Piercing rounds. What better way to test a bullet proof baby stroller than to put a baby in one and open fire. Seriously. Check out the video.
Implications - The featured video is actually hard to believe! The adorable baby gets handed over and placed in the bullet-proof baby stroller. The woman then takes fire at the stroller while the baby is secured inside. When she takes the baby out, he seems completely unfrightened! Hopefully you won't need a bullet-proof stroller for your little one.
Bullet-Proof Baby Stroller
More Stats +/-
3D-Printed Titanium Watches
Lightweight Ventilated Shoes
Vitamin-Delivering Fitness Wearables
Simplistic Bauhaus Sneakers
Branded Celebrity Channels
Bullet-Proof Baby Stroller
Aug 23, 2007 Updated: May 25 2011By: Alex Covert -
References: bulletproofbaby.net & slashgear
References: bulletproofbaby.net & slashgear


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Select Local Merchants
J C's Chick'n TroutRead MoreIf you have yet to try J C's, now is the perfect time to visit the top-rated restaurant. Whether you are heading there for the excellent quality, lightning-fast service, or both, you will never leave this restaurant unsatisfied. There's no specific recommended attire, so feel free to dress casually and comfortably. Also, though the overall price can be a bit on the low side, you won't be sacrificing any quality. In fact, you should be able to enjoy a good meal for $11 or $12, and can probably get in and out for $8 if you try. When you get there, think about ordering the potatoes, as they've gotten rave reviews. In terms of the restaurant itself, if you're searching for the perfect spot for a family gathering, it's been reviewed as a great local option for big groups and families with kids. In addition to its convenient take-out offerings, the restaurant even provides catering for events around town. Specializing in lunch, making a trip to J C's is never a bad call. Don't worry about trying to find a spot on the street, as visitors to the restaurant do have access to a private parking lot nearby.2321 North Rolling RoadWindsor Mill, MD US
Burger KingRead MoreFor that all-American meal, head to burger house Burger King in Washington's Southwest Washington district. With G-free dishes and fare that's low in fat, you won't feel guilty about dining out at Burger King. Warm weather, delectable dishes, and an awesome atmosphere make for a dream night out at Burger King. Can't find your khakis? No problem! Throw on a pair of your most comfortable jeans and you'll blend right in at Burger King. If time is of the essence, this burger joint's take-out option may be a better fit. At Burger King, drivers will appreciate the ample parking options in the area. Enjoy a night out on the town at Burger King and score food and beverage deals and steals. Burger King dishes up breakfast, lunch, and dinner, so stop by for your favorite meal. Fresh-off-the-grill burgers await you at Burger King, so be sure to try one today!195 Chappie James Blvd SWWashington, DC US
SubwayRead MoreDressing up the traditional sandwich, Subway is a go-to lunch spot in Capitol Heights' Seat Pleasant district. Subway is also a great pick for restricted eaters, with plenty of low-fat, vegan, and gluten-free items on the menu. Bring the Subway's great food to your place. Don't feel like driving? Public transportation is right around the corner, with a nearby stop at Addison Road Metro (Blue). Diners will appreciate the quick and easy parking options located near this dining establishment. Thrifty eaters will also love Subway's prices, which are generally below $15. Stop by for three square meals a day — Subway serves breakfast, lunch, and dinner. The sandwiches at Subway are stacked with tasty ingredients, so swing by today and try one. When your stomach starts growling, pay Subway a visit and satisfy your hunger in a flash.6262 Central AvenueSeat Pleasant, MD US
Popeyes Louisiana KitchenRead MorePopeyes Chicken and Biscuits' chicken — cooked just the way you like it — is a must-try in Woodlawn's Woodlawn area. No need to be formal, business casual will pass. If you're strapped for time, take out food from this restaurant. Impress the patrons at your next gathering by calling in Popeyes Chicken and Biscuits for catering. Waiting can feel like forever, especially when you're hungry. Spare yourself time spent in the parking search and dine with us. We've got space available for you and your car. The dream is to eat an amazing meal for under $15, and at Popeyes Chicken and Biscuits, they are making dreams come true. There's definitely no better place to go for a mouthwatering helping of chicken than Popeyes Chicken and Biscuits.1811 North Rolling RoadWoodlawn, MD US
SubwayRead MoreGrab a quick and tasty sandwich for lunch or dinner at Subway. Find all of your favorite eats in one place at Subway, including low-fat, vegan and gluten-free options. Sit back, relax, and enjoy the beautiful weather during your meal at Subway. Always five minutes behind schedule? Pick up your food to go instead. Subway is located near endless parking options, allowing diners to find quick and easy parking. Head on over to Subway first thing in the morning or last thing in the evening — Subway is open for breakfast, lunch, and dinner. So you'll want to head in soon to Subway to get that perfect sandwich to complete your day. Subway serves up delicious eats in a matter of minutes, so head on over today and enjoy a quick bite.6900 Dogwood RoadMilford Mill, MD US
Shaheen Restaurant Indian Pakistani FoodRead MoreTraditional Indian cuisine can be found at Shaheen Restaurant Indian Pakistani Food. Gather up your group of friends and head to Shaheen Restaurant Indian Pakistani Food, a local restaurant that has room for large groups. You can also have Shaheen Restaurant Indian Pakistani Food cater your next event. Forget the hassle of street parking and head to Shaheen Restaurant Indian Pakistani Food for easy access to parking lots. Your bill at Shaheen Restaurant Indian Pakistani Food will typically run less than $30 per person, so bring the whole gang! So when you have a hankering for some Indian fare, head on over to Shaheen Restaurant Indian Pakistani Food and get your fix.6901 Security BoulevardWoodlawn, MD US


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Yellowmoon Cafe
The Yellowmoon Cafe is a cozy coffeehouse which features live music Thursday, Friday, and Saturday evenings and most Sunday afternoons. We serve all types of coffee and coffee specialty drinks, local wines, and the best milkshakes in Southern Illinois.
Twin Bluffs B&B
Enjoy your stay in one of our comfortable rooms with your own queen-sized bed to relax in after an active day enjoying the outdoors. Private garden-patio entrance, scenic views and private stocked pond.
Cannon Park
This beautiful Carterville park includes a community center, baseball field, skate park, walking path that surrounds a fishing pond, volleyball courts (sand), playground, pavilion, gazebo, and memorial garden. Ballfields and shelters can be reserved.
John A. Logan College O'Neil Auditorium
Located within the John A. Logan Community College, this 316 seat theater is host to many collegiate and community performances.
Lake Tree Inn & Suites
Luxuries suites located just off exit 45 on I-57 within walking distance from a gas station, convenient store, restaurant, and lounge. There are 20 rooms. Some facility amenities include a business center, free parking, pets allowed, suites, laundry services, hot tub/jacuzzi, complimentary breakfast, and an on-site bar/restaurant.
17th Street Bar & Grill
Award-winning BBQ. Family style dine-in and carry out. "Best Ribs in the U.S." by Bon Appétit Magazine and featured on the Food Network show, Bon Appétit Picks the Best.
Hickory Ridge Public Golf Center
One of the most challenging courses in Southern Illinois, this championship caliber 18-hole layout plays over 6,800 yards from the back tees. The course has a distinctive links appearance, even though it is cut through the typically hilly local terrain.
Orlandini Vineyards
This four acre vineyard hosts three acres of Chambourcin and an acre of Vignoles, which are two of the best grapes to grown in our region. The vineyard and winery is still in full operation run by the Orlandini family with the commitment to providing the top notch quality vintages our customers have grown to expect. When visiting Orlandini Vineyard, customers can enjoy a tranquil experience with a knowledgeable staff to help guide you to find the best wine for your palate. During warmer weather, we offer live music on Saturday afternoons, and our delicious old world style sangria. Year round we offer a variety of beers including local options. We are a family friendly operation that encourages guests to spread out into the yard and spend the day with us.
Rock Ridge
Located on 140 private acres nestled in ancient bluffs, loaded with wildlife, peace and quiet and everything at your fingertips! We provide everything you and your guests need for a wonderful getaway! The kitchen is fully equipped with all manner of cooking needs, along with a backyard BBQ, all you need is your provisions to whip up a meal to be enjoyed in this wonderful home! The great room has floor to ceiling windows to take in the breathtaking views that span for 40 + miles to Kentucky! It features a flat screen tv and blue ray dvd player along with a cozy gas fireplace for your enjoyment...Also located on the main floor is a laundry room and half bath. Upstairs you will find a log style King Bed Master Suite. There is a walk in closet and a 4 piece Master Bath that rivals any Spa. The walk in shower has body sprays and the jacuzzi tub has a multitude of jets to enjoy while gazing out the window in the tree line! There is a private balcony off the bedroom to take in the views of the bluffs. Downstairs, the walkout basement offers another living area complete with a flat screen tv/dvd player. There is another full bathroom and two more bedrooms, one with a King bed and flat screen tv/dvd player and another full size bedroom. The patio off the living room provides ample shade in the Summer and again you have spectacular long range views of the area! Outback you can relax on the deck while BBQ'ing or watching the kids on the playset. There is ample parking for you and your guests. Rock Ridge also offers guided repelling and climbing, there is a fully stocked pond, and plenty of room to roam around and explore the property!
The Bar B Q Barn
One of Harrisburg's most popular home cooking restaurants, the speciality is fresh pit style BBQ sandwiches. Open Monday through Saturday for breakfast, lunch and dinner. Stop in before hiking in the Garden of the Gods.
Newman & Camden Co.
Newman & Camden Co. is a walk in Bakery/Deli. They serve bagel, donuts, and great breakfast sandwiches. Lunch consists of a daily special, flatbreads, and like the Slow Roasted Turkey & Avocado BLT. All Items are made from scratch!
Williamson County Historical Museum
Located in an historic brick building in Marion, the museum features artifacts, antiques, and records of a bygone era. 17 rooms contain exhibits, including an old-fashioned school room. Tours may be arranged through the Marion Chamber of Commerce.
Crab Orchard Kennel Club AKC Dog Show
This Annual AKC Dog Show boasts many additional amenities. Sign up to bring your dog to the hearing clinic or get their nails trimmed while you wait. Over 100 breeds will try to make it to the Best In Show ring. There will also be vendors of dog treats, toys, beds, blankets and more.
Cache River Basin Vineyard and Winery
Located in beautiful southern Illinois just south of the Cache River. We have a very nice restaurant next to the winery called Wineaux's Restaurant. We also have a cabin on site tucked away at the edge of the woods. Can sleep six, has a hot tub and sauna.
Shawnee Hills Country Club
This fun, challenging course includes nine, 36 par holes, and is open spring, summer and fall. The club offers a full pro shop and snack bar.
McLeod Theater
This 488-Seat theater hosts several productions each year that features both student and guest performers. During the academic year there are four major productions. The McLeod Summer Theater also produces three or four to finish out the season.
Bella Terra Winery
Bella Terra Winery is nestled in the beautiful surroundings of Johnson County, Illinois. With a scenic view of ponds, trees, and our vineyard we provide the perfect setting for sipping wines or celebrating special occasions. Bella Terra Winery was not created just for wine connoisseurs, we offer food and activities for the whole family. You can play bocce ball, throw a game of washers, watch your favorite team on T.V., or just relax under a tree and enjoy the breeze.The manicured grounds of Bella T Winery combined with beautiful shade trees create a striking backdrop for any occasion.
CITY:Creal Springs
Shawnee Forest Cabins
Brand new log cabins in the Shawnee National Forest. Closest cabins to the popular Garden of the Gods hike and just a short drive to many more. One and Two Bedroom cabins available all year. Hot tubs, Fireplaces, DirecTV, FiberOptic High-speed internet, fully furnished, with fire pits, free firewood, and charcoal grills. All cabins have full kitchens, towels, linens and all amenities; just bring your food and fun! Located at 745 Garden of the Gods Rd, Herod, IL. Please visit our website for more information and availability
Monte Alegre Vineyard & Cellars
Monte Alegre is a family owned and operated winery located in Carbondale, Illinois. The winery tasting room opened for the public and visitors in 2009 and has been retailing a variety of eight different wines, all wines made from grapes grown, fermented and aged at location in their cellars. Monte Alegre Vineyard and Ponce Cellars offer spectacular views and prime red and white wines that have made Southern Illinois a favorite tourist destination for wine lovers and their families throughout the Midwest. You can also try a port or a sangria, all in a single stop. The main grapes grown at Monte Alegre Vineyard are Vidal Blanc, Chardonel, Seyval Blanc, Traminette, Norton, Chambourcin, Frontenac, Cabernet Franc and Sangiovese. During the harvest season, July to October, you can also enjoy vine ripened table grape varieties like Reliance, Mars and Fredonia.
Mack's Lake of Egypt
They offer new and used boats, seasonal slip rental, boat lauch, boat dock and lift sales, rental pontoon boats, rental fishing boats, full line of boating accessories, full convenience store, package beer, liquor and wine.
Midland Hills Golf Course
Among the abundant hills and lakes of Southern Illinois, you will find one of the most scenic, oldest and one of the most challenging course in the area. Come out and enjoy the fun.
Tres Hombres
Live entertainment. Monday night is jazz, Thursday offers an eclectic mix of local musicians, Sunday is DJ night.
Holiday Inn - Conference Center
Award winning hotel, receiving the Holiday Inn's Service Excellence and Torchbearer Awards in 2008. Built in 2006, it features five stories, 100 sleeping rooms and meeting spaces available. It's an excellent venue for a convention, as it's attached to Boondocks Seafood Co. which provides exceptional catering.
Lafayette Inn
Located in three historic structures covering 2/3rds of the city block, two blocks west of the public square on Route 13.
Marion Soccer Complex
This soccer facility has 10 fields for grades K-12. 4 Fields are large enough for adult games. Bleacher seating available on the 6 larger fields and seats approximately 40 per team. There are 2 large picnic shelters, playground equipment and a concession stand. Parking for 400 is available.
HalloWine at StarView Vineyards
Live music, wine tasting, nacho & chili bar & other goodies. Come dressed to impress in your best costume for a chance to win prizes. We'll be judging individual, couple & group costumes. Pets & children are invited too!
Four Seasons Campground
Stop on by and enjoy the friendly, peaceful atmosphere. Spacious shaded sites. See an abundance of wildlife. Also available: wireless internet, L-P gas fill, dump station, large pull through, 31 full hook-up sites, 12 pull through sites, (20, 30 and 50) amps available. Public access to: city park, lighted walk path, shower house, laundry facilities/handicap accessible. Cabin rentals available.
University Mall
The University Mall is the centerpiece of Southern Illinois' most established retail district and is conveniently located near the crossroads of two of the regions most traveled arteries -- Route 13 and US 51. The mall features variety stores to meet your shopping needs!
VF Factory Outlet Mall
Enclosed mall with ten stores. Walkers welcome. Restaurants nearby.
CITY:West Frankfort
Rosebud Antique Mall
With over 50 vendor spaces, Rosebud Antique Mall offers high quality antiques and collectibles for all budgets. Primitives, fine antique furniture, quilts, china and glassware, pottery, jewelry, toys, framed art, comics, stained glass and many other unique items fill our clean and well-lit space.
John A. Logan College Autumn Fest
This annual event features over 100 original, handmade arts and crafts, great food, free admission, and free parking. For more information call 1-800-851-4720, extension 8287.
Kokopelli Golf Club
This 18-hole course, designed by renowned golf architect Steve Smyers, was named by Travel + Leisure as one of "America's 100 Best Courses for $100 or Less." Kokopelli offers a full-service pro shop, professionals who offer personal golf instruction and an eight-acre practice facility. This course has a restaurant, lounge, and banquet facilities available.
Cedar Lake Ranch
Cabin rental near Cedar Lake, horse campground, tack store and outdoor recreation
Ferne Clyffe State Park
The lush vegetation of the 2,430-acre Ferne Clyffe State Park, located near the small town of Goreville, hides the fact that directly below the soil, a vast area of rock formations exists. The two main areas for rock climbing include Big Rocky Hollow and the Cedar Bluff areas. Cedar Bluff offers both traditional and sport climbing, including several short, but difficult, routes in the class 12 to 13 range that appeal to experienced climbers. Other routes include top-rope access and solid anchors that appeal to new climbers.
Water Valley Inn
Water Valley Inn can accommodate individuals, couples, families and groups up to eight, based on double occupancy. The main floor of the farmhouse includes two bedrooms with queen size beds and one bathroom. The upstairs has three rooms set up with twin beds.
Super 8 - Harrisburg
Hot tub- suites available free continental breakfast- non smoking & handicapped rooms available.
Firefly Valley
This 2600 sq. ft beautiful 3 bedroom. 2.5 bath cabin is located on 75 secluded acres on the Shawnee Wine Trail. This picturesque and secluded property is within two miles of Blue Sky winery,Owl Creek, and within 1 mile of Orlandini winery. Located on Rocky Comfort Road, you are in the heart of Southern Illinois Wine Country. Enjoy the huge deck overlooking the Valley and the peacefulness of the 140 acres of the Shawnee National Forest which adjoins the property. The opportunities and possibilities are endless.
John A. Logan College Museum and Gallery
Named after Civil War General John A. Logan, the college combines modern architecture and a beautiful park-like setting. Memorabilia of General Logan and his wife, Mary, are on display in the museum and art gallery at the college.
Little Egypt Arts Association Art Centre
Little Egypt Arts Association is a not for profit artist Co-op that was established in 1995 by approximately 20 local artists and art patrons. It's the largest cooperative art center in Southern Illinois. Offering a gift shop, art classes and workshops.
The Science Center of Southern Illinois
The Science Center of Southern Illinois is the perfect way for kids to explore the beauty of science in a fun atmosphere. This hands-on children's museum has over 50 exhibits and sees nearly 15,000 annual visitors. Adults are also welcome, as many of the activities can be enjoyed by all.
Lincoln Heritage Winery
Offers complimentary tastings of hand crafted wines and frequently offers special wine recipes to sample as well. Gourmet cheeses, salamis and crackers are available for purchase and you are invited to bring a picnic basket filled with your own goodies. There are a small selection of other beverages on hand.
Blue Sky Suites
Suites over the tasting room at Blue Sky Winery, with beautiful views of the vineyards and pond.
Grand Rivers Spirits
A locally-owned craft distillery in Southern Illinois, Grand River Spirits creates a selection of spirits that showcase the delicious fruits and grains of Southern Illinois. This national award-winning micro-distillery offers brandy, whiskey, bourbon, rum, seasonal spirits (such as grappa and schnapps), and of course Red Eye Moonshine. Don't let their small size fool you, all of the storage, packaging, distilling and tasting is housed under one roof. See the action for yourself — Grant Rivers Distillery offers free 30-minute distillery tours for up to 10 people by appointment only, available Friday evening, Saturday and Sunday.
Union County Musuem
General museum featuring local history, Kirkpatrick Pottery, Native American artifacts, pioneer items and other unique collections.
Southern Illinois Boat & Fishing Show
A weekend long event sponsored by the Youth Outdoor Education Foundation and the Williamson County Tourism Bureau. The show features boats, trailers, trucks, ATVs, fishing tackle, live entertainment and more. Admission and parking is free. Great fun for all ages.
Economy Inn & Suites
Well established, friendly hometown motel. Queen beds, specials, kids free under 12, free coffee and tourism information. Close to Shawnee National Forest and Garden of Gods Recreation Area.
Saluki Stadium
We would be lying if we didn't say that Saluki Stadium is one of the best college stadiums in the Midwest. Constructed in 2010, this facility is home to the NCAA Division One SIU Football Team and can seat up to 15,000 fans. Enjoy the afternoon with sports, tailgating and more at the Saluki Stadium.
Egyptian Hills Campground & Marina
Eastern side of Lake of Egypt. Facility offers full service, boat rentals, restaurants, bait, tackle, guide service, launching and RV rentals.
CITY:Creal Springs
Doughboy Statue
A World War I memorial stature, "The Spirit of The American Dough Boy" was dedicated on September 6, 1927 following its acquisition through a project sponsored jointly by the local American Legion and VFW Posts. The solider is forever immortalized in statue form, seen is his war apparel and stance. The Dough Boy is a symbol of freedom and remembrance of those who fought for our land.
Anthill Gallery & Vintage Curiosities
Anthill productions is home to the photography of rare images' Bob Hageman and the stained-glass work of Firelight Studio's Linda Austin. For well over 20 years, Linda and Bob have been making and displaying their unique artworks throughout the Midwest, and they are now for the first time making them available to a broader audience.
Cabin at Mountain Glen
The Cabin boasts a vaulted great room with fireplace, full kitchen, a luxurious main floor master bedroom and bath with a custom 2 person shower and Jaccuzi tub. The huge second floor lofted bedroom and 1/2 bath overlooks 20 acres of pasture and wildlife.
Cedar Ridge Whitetails, LLC
Trophy whitetail hunts in scenic Southernmost IL. Hunts are offered September 15th through December. The farm consists of mature timber, pine and cedar thickets, thick draws and open area food plots. All hunts are with an experienced guide.
Lost Coyote Camp
One room cabin rental near hunting, fishing, biking and horseback riding areas.
Pepper Fest
Celebrate the pepper harvest from 11am to 5pm, A favorite gathering for all chile heads and hot pepper fans. Walk the pepper field and see many varieties of hot peppers in bloom, meet the vendors and see who makes the best hot/spicy food, visit the Pepper Farm Store and select your favorite salsa, jellies, spices and pepper products, relax, visit with friends, enjoy great local music and soak in great southern Illinois pepper heat. 618-893-1443. www.darnhotpeppers.com
Windy Hill Acres Inn
Windy Hill Acres Inn is located in the Shawnee National Forest. The Inn is a Rock Potato House which has been remodeled into a beautiful 5 room house with deck. The Potato House was built in the 1800's and used to store the farmers' sweet potatoes.
Fat Patties
Locally-owned and operated, this quirky restaurant not only serves some of the best burgers around, but it also serves as a venue for local music. Most dishes are cooked with local veggies, beef from Lick Creek Beef and Bison from Bison Bluff Farms, ensuring that the customer truly has the freshest meal possible. The highly-recommended "Bucky Dome" burger, named after one of Carbondale's favorite historical figures, is made of local beef, piled high with brisket and cheddar cheese, topped with bacon and fried egg. As If your mouth isn't watering enough right now, you'll have to taste it for yourself! Enjoy free, live, local in house music every weekend in the Red Corner.
Cedar Lake
Located in the Shawnee National Forest, this 1,750 acre lake has 40 miles of shoreline, a maximum depth of 60 feet, and 10hp limit on boat motors.
Marion Main Street Hubfest
All day event featuring car show, food vendors, and live entertainment. Lots of activities for kids including bounce houses, face painting and games. Street fair all day long.
Devil's Kitchen Lake
This 810 acre lake with a maximum depth of 90 feet and a 24-mile shoreline is part of the Crab Orchard Refuge. It is stocked with rainbow and brown trout and provides largemouth bass, bluegill, sunfish, crappie, channel catfish, bullheads, and carp. Boat ramps are available. Boats have a 10-horsepower limit. Camping is available.
Little Grassy Lake
Little Grassy Lake Campground and Marina is located on Crab Orchard National Wildlife Refuge and is a destination stop for returning campers, boaters, and sportsmen. They offer full service camping, primitive camping, boat rentals, concessions, and a bait shop. Reservations accepted to reserve boats and campsites. Pontoon boats, fishing boats, and kayaks can be rented. You don't want to pass up the opportunities to explore the thirty miles of shoreline and embrace the solitude you will find on the lake. The 1200 acre lake is stocked with catfish, crappie, and bass, and offers plentiful oppourtunities for fishing, paddling, boating, and wildlife observation. Amenities include waterfront camping sites, remodeled bathrooms with hot showers, dump station, swimming, pets allowed, monthly educational programs and a renovated concession/bait shop which is stocked with minnows, crickets, camping supplies, cold beverages, food items, ice cream, firewood and ice.
Saluki Basketball
The home of Saluki basketball is the Southern Illinois University Carbondale Arena, a 10,000-seat facility that also hosts national touring concerts, family shows, theatrical events and circuses.
Illinois Iron Furnace
Step back to Civil War days when "pig iron" was smelted at this, the first coal-fired iron furnace in Illinois, now on the National Register of Historic Places. Restored structure is in a beautiful park with fishing, hiking, and picnicking available.
Southern Illinois Miners Rent One Park
The Southern Illinois Miners Rent One Park is the stadium where The Southern Illinois Miners Frontier league baseball team plays from May through September.
Hilltop Hideaway
Located within the Shawnee National Forest in beautiful Hardin County Illinois, just minutes away from Garden of the Gods and Cave In Rock. The cabin offers 1 queen Bedroom with a Kitchen/living area, full bath and a great room with a king, full and a twin bed.
Carriage House Lake of Egypt Luxury Rental
There are 2 units. Some facility amenities include free parking, outdoor pool, on-site fitness center, and hot tub/jacuzzi. The Carriage House is located on one of Lake of Egypt's finest waterfront homes. Enjoy three acres manicured grounds with rose garden, waterfall, fountain, swimming pool, boat dock, paddle boat, private patio with a stunning view of the Lake of Egypt.
Gambit Golf Course
This championship par 71 golf course, designed by Richard Osborne, snakes through meadows and woodlands. The Gambit features the area's only indoor practice center, with two state-of-the-art golf simulators and a nine-hole practice green.
Southern Illinois University Arena
This 10,000-seat facility is located on the beautiful campus of Southern Illinois University Carbondale. The Arena is home to NCAA Division 1 basketball team, the SIU Salukis. The Arena also hosts nationally touring concerts, family shows, theatrical events and circuses.
Trails End Lodge Steakhouse and Saloon
Trails End Lodge is a new steakhouse and saloon, featuring traditional steakhouse cuisine, indoor and outdoor dining, live entertainment, and a friendly atmosphere all served in a rustic, yet luxurious western style lodge. Trails End Lodge is located in the heart of Southern Illinois wine country on scenic Skyline Drive between Cobden and Alto Pass, Illinois. The Lodge itself is not visible from Skyline Drive, so watch for our sign!
StarView Vineyards
StarView Vineyards is a family owned and operated winery and vineyard located in beautiful southern Illinois along the Shawnee Hills Wine Trail. Our vineyards are continuing to expand and today we grow seven varieties of both Native American grapes and French American Hybrids. About 90% of the wine that we make comes from grapes that we grow in our vineyards. We are open daily, year round, and invite you to come enjoy our award winning wines on our deck and take in all the beauty that surrounds us. StarView is one of the premier destination wineries in the region. We have entertained tens of thousands of guests, hosted weddings, parties and weekend music series. We are pet friendly, so bring your 4 legged family member along with you. Our café offers delicious homemade food or you can bring your own picnic. We are excited to share our vineyard and wines with you and we hope you come by to visit us and become part of our story too!
Lucy's Place
Lucy's Place is an upscale neighborhood coffee house / pub located along major intersections where customers can play their favorite video poker and slot games while enjoying a snack with a drink without the crowd and noise of the bar scene.
Anderson Cabin - Vienna
Cabin sleeps 4, kitchen, bath. Fishing at front door, remote location, joins Goose Pond on North.
Marion Cultural and Civic Center
The Marion Cultural and Civic Center serves Southern Illinois as an outlet for cultural and artistic opportunities of all types. MCCC is a 1094 seat performing arts center located in the historic town square of Marion, IL. In addition to providing a state-of-the-art theatrical facility at a low rental cost, MCCC also provides a portion of the lobby to display paintings and artwork from Southern Illinois artists.
Cedar Lake Trail
A 10-mile trail on the west side of Cedar Lake from north to south. Encircles Little Cedar Lake.
Williams Hill Pass
The bunkhouse cabins accommodate four people. Each cabin includes heat, air-conditioning, electricity, table and chairs, a full bed bunk bed and linens. Picnic tables and fire rings are provided outside the cabins for meal preparation. Showers and bathrooms are located in the air conditioned shower house at the Welcome Center. Williams Hill Pass is a family-oriented OHV park located between Mitchellville and Rudement just off Illinois Route 34 in southern Saline County on the north slope of Williams Hill, the highest point in Southern Illinois.
Walkers Bluff Winery
Local winery with a General Store, 5 star cuisine at Legends Restaurant, wine cave, open air pavilion, gazebo and much more. Enjoy a glass of wine while listening to live entertainment. Boasts a large childrens play area, large handcarved sculptures, and even a full service gas station at the general store. You must visit to see the magnitude of this destination.
Extreme Kids
Kids will enjoy three huge bouncers, two in-ground trampolines, and an awesome jungle gym with a ball pit and a 16-foot slide. Also offers dance, cheer, tumbling, wrestling, and gymnastics classes.
Olde Squat Inn Bed & Breakfast
Enjoy beautiful Southern Illinois in our original cabins from the 1800s. Cabins with fireplace, porch and Katy's country style cooking. It has 8 rooms and some of the facility amenities include free parking, park, full breakfast, packages available, pets allowed.
Gem & Mineral Show
Annual Gem and Mineral Show showing off Indian artifacts, fossils, lapidary displays, shell crafts and much more.
Lucy's Place
Lucy's Place is an upscale neighborhood coffee house / pub located along major intersections where customers can play their favorite video poker and slot games while enjoying a snack with a drink without the crowd and noise of the bar scene.
Southern Illinois Raceway
Watch Outlaw Micro Sprint, Junior Sprint Cars, Non-Winged Outlaw and Restricted Micros race every Saturday night at 7pm.
Flamm Orchards Fruits and Cream
Take a drive out to the orchards and buy in-season strawberries, peaches and apples. Flamm's Fruits & Cream Stand offers treats like strawberry shortcake, cobblers, apple dumplings and pies. We sell desserts out of our concession window. Picnic seating available.
Southern Illinois Miners Baseball
The Southern Illinois Miners are a professional baseball team based in Marion, IL. The Miners are a member of the East Division of the independent Frontier League. Since 2007, the Miners have played their home games at Rent One Park. The "Miners" name refers to the Southern Illinois region's history of coal mining.
Saline Creek Pioneer Village
This fascinating pioneer village includes the original Saline County Pauper Farm (now a three-story museum), an old jail, an 1859 one-room schoolhouse, the Cain Church, several 1800s log cabins, a barn and country store.
34 Ranch Horseman's Campground
34 Ranch offers the largest privately-owned horseman's campground in Southern Illinois. Located in Hardin and Pope Counties in the midst of the beautiful Shawnee National Forest. Open year round. One cabin is primitive without plumbing. The other two have both baths and kitchens. The ranch also has 250 modern campsites and can accommodate RV's. Rents out cabins and one trailer. Owner: Tom Luchies.
Cedar Sunset Cabin
Two bedroom log cabin offers a private setting with full kitchen and a hot tub to soak in while you enjoy the amazing sunset views. The spectacular views at Cedar Sunset Cabin are just one of the amazing amenities. The cabin provides you with top notch accommodations on the Shawnee Hills Wine Trail and on the edge of the Shawnee National Forest. Or you may opt for an evening in by the fireside or a soak in the hot tub.
Rocky Comfort Cabins
On the wine trail and walking distance to Blue Sky Vineyard, complete privacy and relaxation all await you at our unique, luxurious cabins: the whimsical Hobbit House, a romantic getaway for two (hot tub, gas log fireplace, fire pit...), and the gorgeous two bedroom, two bath Creole House, with its wrap around porch, hot tub, fireplace, fire pit and more. Romantic ambiance, upscale amenities, and spectacular views will allow the stress to just melt away and the rest of world to disappear. Partially solar powered, the premium location offers the perfect point at which to settle in for a few days and explore the natural beauty and diversity of the Shawnee Hills. The best part? Get a bottle of wine "to go" from Blue Sky Vineyard and take a romantic sunset stroll back to your own hidden slice of heaven. The Hot Tub is waiting.
Blueberry Hill Farm
U-pick strawberries, blueberries and blackberries in Season. May-July 8am to 8pm
Cache River Wetlands Center
The Wetlands Center provides a one-stop shop for information about the Cache River Wetlands and its recreational and educational opportunities. The center has an extensive natural and cultural history exhibit, wildlife viewing, trails and a video.
Tom Cat Hill Cabins
Located off the Shawnee Hills, 5 miles north of Alto Pass on IL 127,(2 miles from Cedar Lake) you will find these two luxury cabins, Cabin #1 accommodates eight. Cabin #2 accommodates two. The cabins offer wonderful amenities to create a relaxing enjoyable visit. Some of the special features are gourmet kitchen, hot tub, washer & dryer, gas fireplace; satellite TV, WiFi, DVD/VCR Player, central air & heat. Boat rental are available for patrons - pontoons, canoes, kayaks for use on nearby Cedar Lake. A great ending for a day would be relaxing in the hot tub or sitting on the deck overlooking the Shawnee National Forest.
The African American Museum of Southern Illinois
Permanent exhibits here include African art collections and slave artifacts. Rotating displays have included Underground Railroad message quilts and local artwork. The museum's changing exhibits seek to portray the outstanding achievements of African American citizens.
Honker Hill Winery
Honker Hill Winery is located on the highest point in Williamson County and surrounded by the Crab Orchard Fish and Wildlife Refuge and Shawnee National Forest, Honker Hill Winery produces fine Illinois wines from fruit grown directly at our vineyard. Enjoy great views from our patio near the fireplace, our unique wildlife room, or gazebo or a enjoy a stroll around one of our five large ponds located on the property while sipping on a glass of your favorite wine.
Miss Emily's Cathouse
Miss Emily's is a new gastropub located downtown in Marion Illinois. We serve lunch, dinner as well as craft beers, fine liquors and mixed drinks. The décor is designed to have a burlesque/speakeasy feel with lots of brass and hardwood throughout.
Cabin by the Pond
Provides you with rustic luxury for your well deserved vacation, romantic weekend getaway or business retreat in Southern Illinois. All the luxuries of home – leave your cares & worries behind you while you relax in Carbondale. Cabin one has 4 beds, 3 baths, sleeps up to 4 couples in private rooms (2 futons are also available.) - 10 person normal occupancy can accommodate more. Cabin 2 sleeps 4, Cabin 3 sleeps 2 or 4. Private beach area, pond area, swimming, fishing, canoes & much more. Wheelchair accessible.
Oak Grove Cabin Rental
Brand new private and spacious 3 - 2 bedroom cabins located on 10 wooded acres right in the heart of the Shawnee National Forest. Minutes from Southern Illinois University, Carbondale, the Shawnee Hills Wine Trail and the orchards. Enjoy hiking, biking and much more.
Bell Hill Mansion
On a hill in Union County, Illinois, just outside of Cobden, stands a historic mansion with 5 guest rooms available. Bell Hill is the perfect place for large and small outdoor weddings or, if you prefer, a more intimate setting indoors is available for smaller weddings. Catering services are available.
Touch of Nature Enviornmental Center
Just 8 miles south of Carbondale, Touch of Nature borders the Shawnee Forest. It is a 3,100 acre wooded retreat area perfect for group events. Located in the City of Makanda, IL.


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SDCC: Marvel: Spider-Man and His Amazing Friends Panel
Comic Books
Sideshow Collectibles is releasing a fierce new Gamora Premium Format Figure, based on the character's comic book design, after she received a cosmic upgrade from the Black Vortex.
Sporting a hooded cloak, belt and gold skull decor, the upcoming Gamora figure is being sold with its own Godslayer blade, while an exclusive edition also comes with swap-out knives for a dual-wielding display.
When faced with a roster of characters that includes Captain Marvel, She-Hulk, Storm, Scarlet Witch and Black Widow, it may be difficult to settle on just which of Marvel's female characters is the most badass. Luckily, however, there's a handy infographic to help you decide.
Courtesy of the United Kingdom's MorphSuits, which previously tallied the kill counts of Marvel characters, the graphic ranks 20 heroines and antiheroines in the categories of strength, fighting skills and general "badass rating."
The Guardians of the Galaxy are on their way to Walt Disney World in Florida, and they're coming to dance.
According to the Disney Parks blog, a Guardians of the Galaxy Awesome Mix Tape Dance Party is being planned as part of a "Villains Unleashed" event at Disney's Hollywood Studios Aug. 23. Per the post, guests can dance to the film's best-selling soundtrack — at least until Star-Lord and Gamora show up to retrieve the tape.


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Forrest Gump is a 1994 American epic romantic-comedy-drama film based on the 1986 novel of the same name by Winston Groom. The film was directed by Robert Zemeckis and stars Tom Hanks, Robin Wright, Gary Sinise, Mykelti Williamson, and Sally Field. The story depicts several decades in the life of Forrest Gump, a slow-witted and naïve, but good-hearted and athletically prodigious man from Alabama who witnesses, and in some cases influences, some of the defining events of the latter half of the 20th century in the United States; more specifically, the period between Forrest's birth in 1944 and 1982. The film differs substantially from Winston Groom's novel, including Gump's personality and several events that were depicted. Wikipedia
Jenny Curran: Can I have a ride?
Pickup-Truck Driver: Where are you going?
Jenny Curran: I don't care.
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Home > News > Degussa to invest EUR 50 million in Nanotronics Science
June 28th, 2004
Degussa to invest EUR 50 million in Nanotronics Science
Degussa AG of Dusseldorf, Germany, laid the foundation stone for a new research and development center today at Marl Chemical Park, North Rhine-Westphalia. At the future Nanotronics Science to Business Center, which is to go into operation in 2005, Degussa will be developing innovative solution systems for electronics applications in collaboration with universities and industrial cooperation partners.
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Nanometrics to Participate in the 8th Annual CEO Investor Summit: Investor Event Held Concurrently with SEMICON West 2016 in San Francisco June 22nd, 2016
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Katie's Reviews > Shanghai Girls
Shanghai Girls (Shanghai Girls #1)
by Lisa See (Goodreads Author)
by Lisa See (Goodreads Author)
Katie's review
May 30, 2012
Read from May 13 to 30, 2012
I love Lisa See books, to be fair, but was a little let down by Peony in Love and wasn't sure this would pick back up after slumping a little in the middle. It, however, rallied amazingly at the end and now I can't wait to dig in to the sequel. If you read this, be prepared to have Dreams of Joy waiting in the wings. This book is excellent, well-written and a great story.
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Showing Results: Most Recent
This review is from: Esky Digital Pocket Jewelry Scale 100 x 0.01g, Black
Pros: In my initial testing using new US coinage as reference weights, this appears to be accurate to plus or minus .02 grams. I create recipes that need to be scaleable to food service quantities, and needed a convenient way to accurately weigh spices and seasoning in the initial small scale prototypes. This seems well suited to my need.
Caught this on sale, so price was a small fraction of what I may have paid for something similar.
Cons: At the price, none.
Other Thoughts: 100g capacity by .01 gram, but as noted above, accuracy is somewhat less.READ FULL REVIEW
This review is from: Rosewill RLFL-14001 Cree XPG-R5 LED Search Flashlight (Zoom) Max 450 lumen
Pros: This flashlight features very strong construction of solid aluminum, a focusing lens with an easy push-pull operation using your thumb, and produces an amazing amount of light from a single AA battery, which I prefer to the previous models that require 3 AAA batteries in a fiddly holder. Water resistant.
Cons: None that I have noted. In my opinion, Rosewill has just improved upon an already good flashlight.
Other Thoughts: I bought two of these for a couple of elderly friends who admired a prior model of Rosewill flashlight of machined aluminum that I have bought (and still have). I liked the pictures so ordered a third for myself. This one is lighter weight while still solid, easier to focus, and uses a better choice in battery, thus has become my new favorite.READ FULL REVIEW
This review is from: TATUNG TICT-1500W Induction Cook Top with Stainless Steel Pot
Pros: Cooks very fast and is very energy efficient.
Cons: This makes a slight whining noise when operating
Other Thoughts: I've had this for well over a year now and find that I use this more often than I use my stove. It heats up faster and is way faster to respond to a change in setting (ie: on the stove I lower the setting and it continues to cook for 2-3 minutes before it begins to get lower). I often cook two side dishes on this rather than bother with the stove. I am contemplating replacing the stove with 2 of these on a 30" wide SS table that would fit in the space of the stove, and put a half-pan size convection oven on the shelf underneath. Getting gas for me would involve bottled gas, which would be a bit of a pain, and these make a nice alternative.READ FULL REVIEW


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Utilizing the measured corneal birefringence from a data set of 150 eyes of 75 human subjects, an algorithm and related computer program, based on Müller-Stokes matrix calculus, were developed in MATLAB for assessing the influence of corneal birefringence on retinal birefringence scanning (RBS) and for converging upon an optical/mechanical design using wave plates ("wave-plate-enhanced RBS") that allows foveal fixation detection essentially independently of corneal birefringence. The RBS computer model, and in particular the optimization algorithm, were verified with experimental human data using an available monocular RBS-based eye fixation monitor. Fixation detection using wave-plate-enhanced RBS is adaptable to less cooperative subjects, including young children at risk for developing amblyopia.
1. Introduction
Retinal birefringence scanning (RBS) is a technique to monitor the changes in the state of polarized light retro-reflected from the fundus of the human eye. It was adapted by Guyton and colleagues to detect foveal fixation [1,2]. For fixation detection using RBS, polarized near-infrared light is directed onto the retina in a circular scan (subtending 3° of visual angle), with a fixation point in the center, and the polarization-related changes in light retro-reflected from the ocular fundus are analyzed by means of differential polarization detection. Due to the radially symmetric arrangement of the birefringent Henle fibers about the fovea, a characteristic frequency that is a multiple of the scanning frequency appears in the obtained periodic signal, for example twice the scanning frequency (2f) when the scan is exactly centered on the fovea, as described in detail previously [1,2], which is the case with central fixation. Thus, by analyzing the generated frequencies in the obtained RBS signal, the goodness of eye fixation can be measured.
The main advantage of RBS-based detection of eye fixation over other methods [3], such as scleral search coils, electro-oculography, and video-based eye trackers, is that it does not require eye-gaze calibration. By detecting the radial symmetry of the foveal architecture, RBS directly assesses true foveal fixation of the eye. This advantage makes it possible to investigate less cooperative subjects, including young children and infants at risk for developing amblyopia, commonly known as "lazy eye," which is the leading medical cause of decreased vision in childhood. Binocular RBS has the potential for automatic and reliable screening of infants and young children for misalignment of the eyes (strabismus) [4–6], the most common cause of amblyopia. Currently available photoscreeners can only detect strabismus indirectly and inaccurately via assessment of the positions of the corneal light reflexes.
Previous generations of our so-called RBS-based eye fixation monitor demonstrated reliable, non-invasive detection of foveal fixation [2,7], as well as detection of strabismus [4,5,8,9]. However, as with all polarization-sensitive technology used for retina assessment, RBS is adversely affected by the corneal birefringence, whose variation from one eye to the next caused significant variability of previous RBS signal levels among individuals. Although being relatively constant over the entrance pupil of any given eye, corneal birefringence, which contributes most (~50-90%) to the overall ocular birefringence, varies widely in both its amount (corneal retardance) and orientation (corneal azimuth) from one eye to the next [10,11]. That variability is substantial enough to produce large, uncontrolled differences in the amplitudes of the detected signals in retro-reflective birefringence scanning, and these changes can mask the desired polarization-related changes induced by the retina.
Various methods have been proposed in the literature to factor out or compensate for corneal birefringence [12–18], but all involve a separate measurement and feedback system, an approach that is tedious and not feasible in poorly cooperative children. Also, most applications of retinal birefringence scanning have required stabilization of the subject's head to enable alignment of the instrument's tiny exit pupil (<2 mm) within the subject's pupil.
When testing unrestrained young children, we must use a hand-held instrument with large exit pupils (about 40 x 40 mm for each eye) that can be aimed at the child's eye(s). With varying gaze directions, though, corneal birefringence can vary continuously during a recording with a moving child, so that a method of bypassing rather than compensating for the corneal birefringence is desired, especially in an application that is geared towards children. The most promising approach involves the application of wave plates because of their ability to influence the polarization state of light. When properly applied, they can shift the detected polarization states into ranges that are minimally affected by different amounts and orientations of corneal birefringence.
To achieve a better understanding of the influence of corneal birefringence on the detected RBS signals, we developed a computer model in MATLAB, based on a previously developed mathematical model from our lab [19], simulating retinal birefringence scanning in a double-pass system using Müller-Stokes matrix calculus. Using this computer model, different options for the RBS design could be simulated to allow us to converge on an optical/mechanical design which optimally bypasses corneal birefringence and thus allows foveal fixation detection essentially independently of the various amounts and orientations of corneal birefringence that occur in the population. Our RBS computer model was validated experimentally using an available monocular RBS-based eye fixation monitor [20].
While the previously developed mathematical model, from which the current computer model described in this article was developed, has been shown to predict accurately the frequency and phase of the RBS signal during central and paracentral fixation [19], the effect of varying corneal birefringence on the strength of the RBS signals has not yet been considered, or verified with actual eyes. Thus, we wished to verify the ability of our RBS computer model to assess the variation in RBS signals with different amounts and orientations of corneal birefringence that occur in the population. We wished especially to test the model's ability to guide us to a design using wave plates ("wave-plate-enhanced RBS") that improves RBS signal strength across the population range of corneal retardances and azimuths.
2. Methods
2.1. Computer modeling of retinal birefringence scanning
Each optical component of the eye is characterized by its own Müller matrix (M), with the cornea and retina considered simply as birefringent media that affect the polarization state of transmitted light. Because the birefringence contribution of the crystalline lens is negligible [21–23], it is not included in the model. The double pass into and back out of the eye can thus be described mathematically by multiplying the Stokes vector (), defining the polarization state of the incident light, by the respective Müller matrices for each contributing ocular medium in sequence, i.e. the cornea, retina, reflection from the ocular fundus, retina again, and cornea again. The outgoing Stokes vector, , determines the final polarization state.
The differential polarization signal measured by a polarizing beam splitter and a pair of photodetectors can be considered identical to the measurement of the S1 component of the returning light, which represents Stokes parameter S1.
The cornea is modeled as a linear retarder, specified by a certain retardance (CR) and azimuth (CA). The latter is simply the orientation of the fast axis of the retarder. In general, most corneas should be treated as a curved biaxial crystal with one optic axis perpendicular to the corneal surface and another optic axis parallel to the corneal surface [24,25]. For a light beam approximately perpendicular to the corneal surface, however, the cornea can be approximated as a linear retarder with a fixed retardance [10,25].
The Henle fiber layer is modeled as a radially birefringent medium, with every fiber acting as a linear retarder. Each fiber of the radially arrayed Henle fiber layer is assumed to have the same amount of birefringence (δr) with its slow axis aligned with the orientation of the fiber. The azimuth of the fast axis (θr), therefore, is perpendicular to the orientation of the fiber. As polarized light is scanned around the fovea in an annular pattern, the azimuth of the foveal birefringence depends on the orientation of the fibers at the current scanning position. During simulated central fixation, fiber orientation and scanning angle are identical, thus the azimuth of foveal birefringence is rotating through 360°. During paracentral fixation, however, the orientation of the fibers encountered at the momentary scanning position is a function of the point of fixation, so that the fast axis of foveal birefringence, being perpendicular to the fiber orientation, can be calculated as follows:
where φ is the momentary scanning position, advancing through 360°, and xret and yret are the horizontal and vertical displacements of the center of the scanning circle from the fovea respectively. The amount of retinal birefringence, i.e. retinal retardance (δr), on the other hand, depends on the distance from the foveal center. In the RBS computer model, the maximum retardance is considered to be 15 nm [26,27], increasing from zero in the very center to the maximum of 15 nm ~1.5° from the center, and then tapering off farther from the center. This attenuation away from the center is described by [7]:
where τ1 = 3.7, τ2 = 50, τ3 = 0.6, τ4 = 5, τ5 = 0.8 [7,28].
With central fixation, the 3° annulus formed by the scanned light beam is centered on the radial array of linear retarders, so that the same amount of retinal birefringence, i.e. retinal retardance, is experienced at each scanning position. Thus, given that the eye is fixating properly, the circular scan on the retina can be thought of, and simulated as, a spinning wave plate with a retardance of 15 nm, rotating at the frequency of the scan. For an operating wavelength of 785 nm, as used in our applications, 15 nm corresponds to a retardance of about 7°.
Because reflection from the ocular fundus exhibits a high degree of polarization preservation [29], the fundus is treated as a complete polarization-preserving ideal reflector, modeled by the Müller matrix of an ideal mirror:
As can be seen, the reflection from the fundus simply reverses the signs of Stokes parameters S2 and S3, while the sign of S1 remains unchanged.
2.2. Assessing the influence of corneal birefringence on the RBS signal
Both corneal retardance and azimuth vary from one eye to the next but are reasonably constant over the entrance pupil for any given eye. To consider the different values for CR and CA that occur in the population, we used the 140 eyes (70 right eyes and 70 left eyes) from the data published by Knighton and Huang as a reference [10]. Within the scope of their studies, normal subjects were measured (at a wavelength of 585 nm) to determine the birefringence properties (slow axis and double-pass retardance) of their central corneas. Five additional pairs of CR and CA were included in the assessment, obtained from measurements (in the near infrared) in our laboratory [7]. As corneal birefringence is essentially constant across wavelengths [30], there should not be significant differences in corneal birefringence values between the two data sets. Since our RBS computer model expects single-pass corneal retardance and corneal fast axis (CA), the following calculations were performed to match the corneal parameters in the model: 1) corneal double-pass retardance values were converted to single-pass values; 2) corneal slow axis (CSA) values, measured nasally downward for each eye in the original data set [10], were converted to corneal fast axis (CA) values as follows:
where for the right eyes, CSA corresponds to the negative value of the measured corneal slow axis. This yielded a common azimuth scale for both eyes, ranging from 0° (subject's right ear) to 180° (subject's left ear), with a rough symmetry of right and left eye corneal azimuths about the nose (about CA = 90°). In fact, 99% of right eye corneal azimuths and 96% of left eye corneal azimuths in the data set are between 0° and 90°, and 90° and 180°, respectively. As corneal azimuths between the two eyes are well correlated, r = 0.77 [10], and approximately symmetrical about 90° CA (average meridian of symmetry between both eyes is 92.7° for the subjects in our data set), and because we wanted to derive a symmetric solution to simplify the mechanical construction of the apparatus (further explained below) covering a wide range of potential right and left eye corneal birefringences, we included the mirror image of each eye (mirrored about 90° CA) in the assessment, yielding a total number of 300 representative pairs of CR/CA. In the further course of this paper, the data representing these 300 "eyes" are referred to as the Knighton/Gramatikov data set. The data set contains values, however, from only 75 truly independent eyes plus 75 fellow eyes.
In addition to modeling the effects of ocular birefringence as described above, the RBS computer program provides the user with a means to select diverse optical components and to specify their properties in the double-pass scanning system. These manipulations can alter the polarization state of light in various ways before and after passing through the eye in order to optimize the power throughput and converge toward an RBS design that yields the largest differential RBS signal practically constant over the population range of corneal retardances and azimuths. For instance, additional wave plates can be optionally placed in the light path, single-pass or double-pass (operating in either the incoming path or in the return path, or in both), rotating or fixed, as well as beam splitters, etc. With the help of the Knighton/Gramatikov data set, it was possible to judge if a certain RBS design would fail or excel over a significant proportion of the population (further explained below).
For a given optical arrangement, the model retina is scanned in a circle with incident linearly vertical polarized light ( = (1,-1,0,0)T) 16 times in total (as with our actual RBS-based eye fixation monitors), in incremental steps of 4.5°, thus leading to 1280 "measurements." The resulting periodic RBS signal is Fourier analyzed to determine the predominant component frequencies. More precisely, the Fast Fourier Transform (FFT) is computed on the whole 16-cycle epoch, an epoch long enough to provide good frequency resolution, and the power spectrum values at the frequencies of interest are determined for a range of CR and CA combinations (0 nm to 180 nm CR, and 0° to 180° CA) to cover the variability of corneal birefringence across individuals. These signal strengths (FFT power) at a given frequency are displayed as a function of CR and CA over the entire ranges of these variables (Fig. 1(a) ). Superimposed on the surface of this 3D-plot are the specific pairs of CR and CA of the Knighton/Gramatikov data set, so that it is readily visible how the optical arrangement would perform across a representative group of people. Right eyes (and mirrored left eyes) are indicated as circles and left eyes (and mirrored right eyes) as crosses. In the best case, the surface of the 3D-plot should be flat and high according to the requirements of greatest independence from corneal birefringence. The contour plot, which is generated simultaneously with the 3D-plot, provides another means of judgment about the suitability of a design. This contour plot is simply a flat graph with axes CA and CR, showing in the background the corneal retardance and azimuth of each of the "right" and "left" eyes in the Knighton/Gramatikov data set, upon which is superimposed a contour plot of the signal strength showing where the signal drops down, thereby indicating which eyes are missed when the signal falls below the threshold of 0.4, which has been arbitrarily considered as a measurement failure (Fig. 1(b)).
Fig. 1
Figures 1(a) and 1(b) are the predicted results during simulated foveal fixation with the RBS-based eye fixation monitor used for the purpose of model validation (see 2.3). As can be seen, the RBS signal obtained with the current RBS design implemented into the eye fixation monitor is poor for eyes with very low corneal retardance and goes to zero when corneal retardance is zero. The design is more favorable for eyes with higher corneal retardances, including outliers with very high corneal retardances (up to 125 nm single-pass) excluded in [10]. Moreover, for either eye, the signal falls off with low or high corneal azimuth. More precisely, the signal goes to zero when corneal azimuth is 0°, 90°, and 180°. As shown in Fig. 1(b), 204 of the representative "eyes" (102 of either eye), from the Knighton/Gramatikov data set of 300 "eyes" fall below the "0.4" contour. In other words, with this threshold setting, 68% of the "eyes" in the data set fail with the RBS-based eye fixation monitor. Only weak signals are measured for eyes in the range where the signal strength drops below this threshold of 0.4.
The poor performance for eyes with low corneal retardance suggests that we should add a fixed amount of artificial "corneal" birefringence to the RBS system. In terms of Poincaré sphere representation of polarization states, a fixed double-pass wave plate is added that has the effect of shifting the polarization states of the light incident on the retina to the position on the Poincaré sphere where the retinal retardance will have the greatest effect on the size of the generated path of polarization states, and then on the return path will have the effect of shifting the polarization states of the generated path of polarization states back to the position on the Poincaré sphere where the path of polarization states will project maximally onto the S1 axis – yielding the largest retina-derived S1 signal.
2.3. Validation arrangement: RBS-based eye fixation monitor
An altered version of the monocular RBS-based eye fixation monitor described in Reference 20 was used for model validation purposes. Its RBS system was modified to allow for incorporation of a double-pass retarder at various azimuths, operating in both the incoming and return paths, by means of a custom-made aluminum holder, screwed to the cage cube holding the polarizing beam splitter (PBS) (see Fig. 2 ). The holder is tilted approximately 10° to reduce specular reflections of light from the flat double-pass surfaces of the wave plate back into the system, which would create much optical noise. The retarder can optionally be attached to the angled holder by means of a rotary mount. The rotary mount is graduated in 2-degree increments, allowing manual rotation of the wave plate's fast axis to various verifiable orientations.
Fig. 2
2.4. Optimizing foveal fixation detection using wave plates
We needed to find a double-pass wave plate that would statistically optimize foveal fixation detection with the RBS-based eye fixation monitor, preferably uniformly over the population range of corneal retardance and azimuth. With the objective of maximizing RBS signal strength while minimizing the variability of the scan between eyes and among subjects, an algorithm was developed for optimizing both retardance and azimuth (fast axis orientation) of the fixed double-pass wave plate (WP). In the RBS computer model, the wave plate with unknown retardance, δWP, and azimuth, θWP, was inserted into Eq. (1):
Since the RBS-based eye fixation monitor, due to its monocular nature, allows measurement of only one eye at a time, the optimization algorithm was applied to only the "right" eye data in the Knighton/Gramatikov data set. A solution to the corneal birefringence problem that works for the right eye will yield a mirror-symmetric solution for the left eye. A mirror-symmetric solution greatly simplifies the mechanical realization in the actual apparatus, in that it requires the wave plate simply to be rotated equal amounts about 90°, depending on whether the right or left eye is examined. For the 150 "right" eyes in the available data set, the double-pass wave plate was computed that would statistically maximize RBS signal strength, while having the greatest independence from the various amounts and orientations of corneal birefringence. Optimization was achieved by varying the properties of the wave plate on a grid ranging from 0° to 180° retardance (0 nm to 393 nm at 785 nm wavelength), and from 0° to 180° azimuth. To minimize processing time, both variables were first stepped through in increments of 10° (i.e. 22 nm for the retardance), sufficient to localize the approximate best range of retardance and azimuth, and then in 1° (2 nm at 785 nm wavelength) steps for the retardance and 2° steps for the azimuth, within this best range. An incremental resolution of 2° seemed reasonable for the azimuth of the WP, considering the 2° graduation of the WP rotation mount incorporated in the experimental validation arrangement. For each incremental step, the mean and standard deviation of the RBS signal strengths (FFT power at 2f) of the 150 representative "right" eyes were calculated. The normalized standard deviation, in other words the standard deviation divided by the mean for each retardance/azimuth combination, was then determined, and the minimum of these normalized standard deviations was computed according to the requirement of finding a retardance/azimuth combination that yields maximal signal strength with the least variability across CR and CA. The lowest normalized standard deviation of RBS signal strength for the 150 "right" eyes in the available data set was chosen to identify the best retardance/azimuth combination for the wave plate to add to the monocular eye fixation monitor.
2.5. Method of determining corneal birefringence of studied eyes
Both the corneal retardance and corneal azimuth of our subjects' corneal birefringence had to be known in order to be able to compare the predicted results from the computer model with actual measurements. Individual corneal birefringence was measured with the help of a GDx-VCC instrument (Carl Zeiss Meditec AG, Jena, Germany), available in our institution. The GDx is a commercially available scanning laser polarimeter with an imaging wavelength of 780 nm primarily used for glaucoma diagnosis purposes. The variable corneal compensator version (VCC) of the instrument features two identical wave plates in rotary mounts that allow measurement and individual neutralization of corneal birefringence [14,15]. Given that the examined eye has a normal macula with no disease, the "bow-tie" method can be employed to measure individual corneal birefringence. Corneal birefringence is determined with the magnitude of the VCC set to zero, accomplished by simply rotating both retarders such that their fast axes are perpendicular to each other, in other words with the retarders in the "crossed" position. Macular polarimetry images obtained in this "crossed" position demonstrate a non-uniform retardation map with a distinct "bow-tie" pattern centered on the fovea, reflecting the retardation of the cornea superimposed onto the radial retardation distribution of the Henle fiber layer. The eye-specific corneal polarization axis can be determined directly from the orientation of the bow-tie, with the fast axis of corneal birefringence being aligned with the dark arms of the bow-tie, representing macular regions where the Henle fiber retardance subtracts from the corneal retardance. In contrast, the slow axis of corneal birefringence corresponds to the orientation where the bow-tie pattern is brightest, representing macular regions where the Henle fiber retardance adds to the corneal retardance. The magnitude of corneal birefringence (single-pass corneal retardance) is determined by analyzing the retardance profile along a circle around the fovea, with the slow and fast axes of corneal birefringence corresponding to the maximum and minimum values respectively. Corneal retardance can be computed by performing a least-squares fit of the equation
to the measured macular retardation profile.
Corneal slow axis (CSA) values obtained with the GDx-VCC (measured nasally downward for each eye, as in [10]), have to be converted to corneal fast axis (CA) values as described above using Eq. (5) to match the corneal parameters in our model.
3. Results
3.1. Finding the optimum double-pass wave plate
As shown in Fig. 3(a) below, there are two local areas of minimal normalized standard deviation. With an incremental resolution of 10° (i.e., 22 nm for the retardance), the optimization algorithm measured an absolute minimum with a wave plate (WP) having a retardance of 60° (131 nm at 785 nm wavelength) and an azimuth of 140°. The algorithm was re-applied, varying the retarder properties on a finer grid covering the area adjacent to the absolute maximum (120° to 160° WP azimuth and 50° to 70° (141 nm to 153 nm) WP retardance), in increments of 1° for the retardance (i.e. 2 nm at 785 nm wavelength) and 2° for the fast axis orientation (see Fig. 3(b)). Maximal RBS signal strength with the least variance across the Knighton/Gramatikov range of "right" eye corneal retardances and azimuths was achieved with a 61° wave plate (i.e., a 133 nm retarder at 785 nm wavelength) with fast axis at 144°.
Fig. 3
Adding a 61° (133 nm) wave plate to the RBS design, operating on both incoming and returning paths through the eye, theoretically improves foveal fixation detection with the monocular eye fixation monitor. Figure 4(a) shows that with the added wave plate at the fixed orientation of 144°, the RBS signal becomes very large for right eyes with low corneal retardance. RBS signal strength decreases slightly for eyes with high corneal retardance. But compared with the model predications without the wave plate, the signal is practically uniform across the Knighton/Gramatikov range of "right" eye corneal retardances and azimuths in the population (circles). The worse performance at higher values of CR makes little difference, because there was no "right" eye in the Knighton/Gramatikov data with a retardance above 100 nm. The contour plot reveals that none of the representative "right" eyes (circles) falls below the contour of 0.4 (see Fig. 4(b)).
Fig. 4
3.2. Verification with human subjects
To compare RBS model predictions with actual measurements, six normal subjects (age 26 - 56) were recruited for the investigations, which were approved by the Johns Hopkins University Institutional Review Board and which adhered to the tenets of the Declaration of Helsinki. Prior to the experiment, the nature and possible consequences of the study were explained, and informed consent was obtained from all subjects.
Four of the six subjects had a refractive error of less than ±2.00 D of sphere, and one subject (2) was measured wearing contact lenses to compensate for 5.00 D of myopia. The monocular eye fixation monitor was designed to function with up to ±2.00 D of refractive error. One subject (3) had astigmatism of 1.50 D (right eye).
Knowing the individual corneal birefringence of the six test subjects is required for predicting their individual results obtained with the monocular RBS system, and thus essential for direct comparison purposes between predicted and measured results. Thus, for all volunteers, individual corneal retardance and azimuth were measured with the GDx device as described above. Two macular polarimetry images were acquired for each subject, and the mean corneal retardance and azimuth were used for the analysis, as presented in Table 1 .
3.3. Model predictions for studied eyes
With both corneal retardance and corneal azimuth of our subjects known, the performance of the monocular eye fixation monitor (in terms of strength of the foveal fixation signal) can be predicted for each right eye. To determine the predicted foveal fixation signal strength obtained with the eye fixation monitor, the measured values of corneal retardance and azimuth from Table 1, for each subject, were inserted into the RBS model, which calculated the S1 signal strength during simulated central fixation with the model of the monocular eye fixation monitor, both with and without the added 61° (133 nm) wave plate oriented at 144°. The RBS model predicts that foveal fixation detection is greatly improved for each of the 6 studied right eyes after adding the fixed amount of 61° (133 nm) retardance (see Table 2 ).
As another comparison measure, we also calculated the fast axis orientation for the given 61° (133 nm) wave plate that would statistically maximize RBS signal strength for each subject, using that subject's measured combinations of CR and CA. Individual optimization was achieved by varying the azimuth of the wave plate from 0° to 180° in increments of 2°, for the given retardance of 61° (133 nm). For each azimuth, the FFT power at 2f was computed, and the azimuth with the highest number, that is maximal signal strength, was chosen to be the best orientation for the specific right eye. The results are given in Table 2.
These results show that for our six test subjects a fast axis orientation of approximately 66° (average of Opt. WPA in Table 2) would theoretically be better suited for the right eye measurement with the monocular eye fixation monitor, which lies within the second suggested local area of minimal normalized standard deviation (see Fig. 3(a)). Recall that the optimization algorithm calculated two local areas of minimal normalized standard deviation for the monocular RBS design, with the absolute minimum occurring at 144°, which was optimized for Knighton and Gramatikov's population range of "right" eye corneal birefringence (total of 150 "right" eyes). The modeling results with the wave plate oriented at 66° are shown in Fig. 5(a) in form of the familiar 3D-plot. As can be seen, with the 61° (133 nm) wave plate oriented at 66°, the RBS signal becomes very large and uniform for right eyes with low corneal retardance, but falls off with higher values of CR. Thus, considering the entire population range of right eye corneal birefringence (with the Knighton/Gramatikov data as reference), RBS signal strength is less uniform with the wave plate oriented at 66° than at 144° (see Fig. 4(a)). However, a fixed azimuth of 66° greatly enhances foveal fixation detection for the right eyes of our test subjects, whose highest value of CR was only 37 nm (subject 5).
Fig. 5
Figure 5(b) details, for one subject (#1), the predicted RBS signal strength at 2f as a function of fast axis orientation of the 61° (133 nm) wave plate. The individually-applied optimization algorithm in the computer model predicted an absolute maximum in FFT power at 2f with the fast axis oriented at 62°.
3.4. Measured data from studied eyes
To compare model predictions with experimental data, the right eye of the six subjects was measured with the validation arrangement described in 2.3. Subjects were seated in front of RBS-based eye fixation monitor and were instructed to look into the active eyepiece with the right eye, while placing their forehead against the faceplate to simplify head positioning [20]. Room lights were turned off to enhance pupil dilation, and thus to allow more light to enter the eye. Subjects were asked to fixate centrally on the blinking visible fixation light in the center of the faint 785 nm scanning circle and press the trigger on a handheld pushbutton to initiate data acquisition, maintaining fixation for about half a second until acquisition was complete. This procedure was performed both without and with a wave plate (AX27341, Anchor Optics; Barrington, NJ) added to the double-pass system, which we measured as having a retardance of 61° (133 nm) at our operating wavelength of 785 nm, using the principle of the "crossed" polarizer method [31].
Measurements in the wave plate mode were first obtained with the retarder oriented at the position optimized for Knighton and Gramatikov's population range of corneal birefringence, i.e., at 144°. Next, data were acquired for each subject with the wave plate rotated to the individual optimized fast axis orientation from Table 2. The foveal fixation signal strength measured in each setting is presented in Table 3 (FFT power of the fixation reading, at twice the scanning frequency).
In addition, for one subject (#1), the 61° (133 nm) wave plate was manually rotated through 180° in incremental steps of 10°, and the strength of the foveal fixation signal at each incremental step was measured to experimentally determine the fast axis orientation that yielded maximal FFT power at 2f. With an incremental resolution of 10°, maximal signal strength was measured with the 61° (133 nm) wave plate oriented at 60°. Adjacent to 60°, the retarder was then rotated in 2° steps to find the absolute maximum. The maximal FFT power at 2f was measured with the wave plate oriented at azimuth 64°.
4. Discussion and conclusion
The measurement results show that for all subjects, except one (#4), the strength of the RBS signal during central fixation increased after adding the 61° (133 nm) wave plate oriented at 144° to the optical system, as predicted with the RBS computer model. Note that subject #4 already yielded a remarkably high foveal fixation signal without the wave plate, compared with the signal strength measured without the wave plate for the other tested right eyes, even higher than the foveal signal for subjects 1, 3, and 5 measured after the 61° (133 nm) wave plate had been added to the optical system.
In accordance with RBS model predictions, foveal signal strength is even further increased for the test subjects (except subject #2) with the wave plate oriented at the individually optimized azimuth. This confirms the hypothesis that for our small group of tested subjects, a fast axis orientation of about 66° is better suited for the right eye measurement with the monocular eye fixation monitor, significantly enhancing foveal fixation detection.
For subject #3, RBS signal strength is in general low, which might be explained by the astigmatism present in the subject's right eye, causing less useful light to return to the detector after the double-pass through the ocular system. The eye serves as an efficient retro-reflector only when the retina and the source of light are situated in conjugate planes, in other words with the eye being properly focused on the light source. This assumption is included in the RBS computer model, but it is certainly not valid for the astigmatic right eye of subject #3.
There are possible limitations of the RBS computer model, and possible errors in the assumptions used in its development, that may be contributing to deviations between measurements and model predictions. First, even though polymer retarders, such as the 61° (133 nm) wave plate used, are much less sensitive to changes in retardance with changes in the angle of incidence (if tilted about its fast or slow axis), the 10° tilt, minimizing specular back reflections, could have introduced significant errors with the fast axis rotated to its optimized azimuth. Also, the tilt changes the retarder's fast axis azimuth slightly with respect to the beam reference system. In other words, the actual fast axis orientation will differ from the manually adjusted azimuth on the rotary mount, more precisely it will be shifted towards lower angles. This explains the observed deviation of 2° between measured and predicted fast axis azimuth that yields maximal foveal signal strength for subject #1. The theoretically predicted value, 62°, was 2° less than the measured result, 64°.
Second, different head positioning during the assessment with the GDx instrument and the monocular eye fixation monitor could cause differences in measured and actually present corneal birefringence during data acquisition with the monocular RBS-based eye fixation monitor. In fact, measurements with the GDx are limited to the central cornea, whereas with the large exit pupil used in retinal birefringence scanning, to allow relative freedom of the subject's head, the entire cornea overlying the pupil is used. Thus non-uniformity of corneal birefringence across the pupil of real eyes can be a major confounding factor potentially resulting in inconsistent agreement between model predictions and measurement results. Such irregularity is undoubtedly present with the large pupils induced during the assessment with the monocular RBS-based eye fixation monitor by turning off room lights to allow more light to enter the eye.
Another potential source of error includes the assumption that the fundus acts as an ideal retro-reflecting surface, modeled by the Müller matrix of an ideal mirror. In real eyes only a small portion of the light incident on the retina is reflected (about 1/10,000 to 1/1000 of the light is reflected) [1], which varies across individuals.
Despite the potential sources of errors, the preliminary validation experiments with human subjects using the monocular RBS-based eye fixation monitor showed that the RBS computer model is capable of assessing the influence of varying corneal birefringence on the strength of the differential RBS signal during foveal fixation. The data obtained confirmed the model's ability to predict an appropriate double-pass wave plate, which, when added to the optical system, improves RBS signal strength during central fixation.
In conclusion, the RBS computer program described in this paper allows assessment of the effect of varying corneal birefringence on the strength of the RBS signals. It also provides a means of optimizing RBS using wave plates and other optical components. "Wave-plate-enhanced" RBS enhances recognition of foveal fixation by minimizing the deleterious effects of corneal birefringence. We are currently completing a binocular RBS system incorporating spinning and fixed wave plates [32].
This work was supported in part by gifts from Robert and Maureen Feduniak, Dewey and Janet Gargiulo, David and Helen Leighton, Richard and Victoria Baks, Robert and Diane Levy, and by awards from Research to Prevent Blindness (DG), the Hartwell Foundation (BG), and the Knights Templar Eye Foundation (KI). The authors thank Robert W. Knighton and Xiang-Run Huang for the corneal birefringence data from 70 human subjects, and Carl Zeiss Meditec for providing assistance with the GDx-VCC manuals and a software update.
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