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Visual and Auditory Problems

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University of Toronto Scarborough
Biological Sciences
Stephen Reid

Chapter 22: Visual and Auditory Problems PROBLEMS OF THE EYE REFRACTIVE ERRORS  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. EXTRAOCULAR DISORDERS  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. o Treatment is aggressive to avoid permanent loss of vision. An untreated ulcer can result in corneal scarring and perforation. CATARACT  A cataract is an opacity within the lens.  Symptoms of cataracts are decreased vision, abnormal color perception, and glare.  Removal of the cataract is the most common surgery for older adults. Most patients undergoing cataract removal have an intraocular lens implanted during surgery.  After cataract surgery, the eyes are temporarily covered with a patch and protective shield.  Postoperative nursing goals include teaching about eye care, activity restrictions, medications, follow-up visit schedule, and signs/symptoms of possible complications.  Healing is complete around 6 to 8 weeks postoperatively. RETINOPATHY  Retinopathy is microvascular damage to the retina that can lead to blurred and progressive vision loss.  It is often associated with diabetes mellitus and hypertension.  Nonproliferative diabetic retinopathy is characterized by capillary microaneuryms, retinal swelling, and hard exudates. o Macular edema represents a worsening as plasma leaks from macular blood vessels. o It may be treated with laser photocoagulation.
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