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BIOC33H3 Lecture Notes - Macular Edema, Far-Sightedness, Blepharitis

Biological Sciences
Course Code
Stephen Reid

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Chapter 22: Visual and Auditory Problems
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.
Hyperopia refers to farsightedness.
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.
Conjunctivitis is infection or inflammation of the conjunctiva.
o Acute bacterial conjunctivitis (pinkeye) is common.
o It occurs initially in one eye and can spread rapidly to the unaffected eye.
o It is usually self-limiting, but antibiotic drops shorten the course of the disorder.
Trachoma is a chronic conjunctivitis caused by Chlamydia trachomatis.
o It is a global cause of blindness.
o It is preventable and transmitted mainly by hands and flies.
Keratitis is corneal inflammation or infection.
o The cornea can become infected by bacteria, viruses, or fungi.
o Topical antibiotics are generally effective, but eradicating infection may require
antibiotics administered by subconjunctival injection or IV.
o Other causes are chemical damage, contact lens wear, and contaminated products
(e.g., lens care solutions, cosmetics).
o Tissue loss due to infection produces corneal ulcers.
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