eye disorders
Contact Lenses
Care and Complications of Contact Lenses
Instructions for hygiene and handling lenses must be strictly observed. Poor contact lens hygiene may lead to infection of the cornea or persistent inflammation. Contact lenses occasionally cause painless superficial corneal changes. Contact lenses can be painful when The corneal epithelium is abraded (see Corneal Abrasions and Foreign Bodies ); the eye becomes red, and the cornea stains with The lenses fit poorly (eg, too tight, too loose, poorly centered). There is too little moisture to keep the lens floating above the cornea. The lenses are worn in a nonideal environment (eg, oxygen-poor, smoky, windy). A lens is improperly inserted or removed. A small foreign particle (eg, soot, dust) becomes trapped between the lens and the cornea. The lenses are worn for a long time (overwear syndrome). Overwear syndromecauses redness, photophobia, and tearing. Spontaneous healing may occur in a day or so if lenses are not worn. In some cases, active treatment is required (eg, topical antibiotic eye drops or ointments). Dilating the eye with mydriatic drops can ease photophobia. Mydriatics work by temporarily paralyzing the muscles of the iris and ciliary body (movement of the inflamed muscles causes pain). In overwear syndrome or any other condition in which pain does not quickly resolve when lenses are removed, an ophthalmologist or optometrist should be consulted before lenses are worn again. Risk factors for contact lens–related corneal infection (keratitis) include the following: Poor lens hygiene Overnight or extended wear Use of tap water in the cleaning regimen Eyes with a compromised ocular surface (eg, dryness, poor corneal sensation) Infections require prompt treatment by an ophthalmologist. A Corneal Ulcer , which is a potentially vision-threatening infection of the cornea, is suspected when a contact lens wearer has intense eye pain (both foreign body sensation and ache), decreased vision, redness, photophobia, and tearing. Use of contact lenses increases risk of corneal ulcer. The risk increases about 15 times if contact lenses are worn overnight. Corneal ulcers can be caused by bacteria, viruses, fungi, or amebas. Diagnosis is by Slit-lamp examination and Contact lens use is stopped. Antibiotic eye drops are given empirically for possible bacterial infection. Initial therapy is broad-spectrum, using a fluoroquinolone antibiotic eye drop every 15 to 60 minutes around the clock for the first 24 to 72 hours, then at gradually longer intervals. Additional antibiotic eye drops, such ascefazolin,vancomycin, or concentratedtobramycin, are used if the ulcer is large, deep, or close to the visual axis. The antibiotic may be changed or stopped later based on culture results. Neglected cases may respond poorly or not at all to treatment, and severe vision loss may result. 