eye disorders
Cataract
Cataract extraction and lens implant procedures
Cataract extraction is usually done using a topical or local anesthetic and IV sedation. There are 3 extraction techniques: Inintracapsular cataract extraction,the cataract and lens capsule are removed in one piece; this technique is rarely used. Inextracapsular cataract extraction,the hard central nucleus is removed in one piece and then the soft cortex is removed in multiple small pieces. Inphacoemulsification(a type of extracapsular cataract extraction), the hard central nucleus is dissolved by ultrasound and then the soft cortex is removed in multiple small pieces. Phacoemulsification uses the smallest incision, thus enabling the fastest healing, and is usually the preferred procedure. Femtosecond lasers can be used in refractive laser-assisted cataract surgery prior to phacoemulsification to achieve a more precise, accurate incision and decrease risk of infection. In extracapsular extraction (including phacoemulsification), the lens capsule is not removed. A plastic or silicone lens is almost always implanted intraocularly to replace the optical focusing power of the removed crystalline lens. The lens implant is usually placed on or within the lens capsule (posterior chamber lens). The lens can also be placed in front of the iris (anterior chamber lens) or attached to the iris and within the pupil (iris plane lens). Iris plane lenses are rarely used in the United States because many designs led to a high frequency of postoperative complications. Multifocal intraocular lenses are newer and have different focusing zones that may reduce dependence on glasses after surgery. Patients occasionally experience glare with these lenses, especially under low-light conditions, and also have problems with reduced contrast sensitivity. 