BIOC33H3 Lecture Notes - Macular Edema, Far-Sightedness, Blepharitis
25 Mar 2013
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Document Summary
Refractive errors are the most common visual problems. They occur when light rays do not converge into a single focus on the retina. Myopia, or nearsightedness, is the most prevalent refractive error. Presbyopia is farsightedness due to decreased accommodative ability of the aging eye. Most refractive errors are corrected by lenses (eyeglasses or contact lenses), refractive surgery, or surgical implantation of an artificial lens. A hordeolum (sty) is an infection of sebaceous glands in the lid margin. A chalazion is a chronic inflammatory granuloma of meibomian (sebaceous) glands in the lid. Blepharitis is a common chronic bilateral inflammation of the lid margins. Trachoma is a chronic conjunctivitis caused by chlamydia trachomatis: it is a global cause of blindness, it is preventable and transmitted mainly by hands and flies. An untreated ulcer can result in corneal scarring and perforation. A cataract is an opacity within the lens. Symptoms of cataracts are decreased vision, abnormal color perception, and glare.
