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SENSORY DISORDERS

Cataracts

Opacity of the lens that ↓ visual acuity. Caused by oxidative damage to the lens, leading to ↑ deposition of insoluble proteins in otherwise transparent tissue (Figure 15.1). Risk factors include smoking, diabetes, and corticosteroid therapy.

  • Symptoms/Exam: Presents with painless blurred vision (Figure 15.2). Symptoms are progressive, developing over months or years. Lens opacities can be grossly visible or seen as a diminished red reflex.

  • Diagnosis: Slit-lamp biomicroscopy during ophthalmologic exam (see Figure 15.1).

  • Management: Decision to treat is based on the degree of functional impairment imposed by the cataracts. Surgery consists of removal of the cataract and placement of an intraocular lens; improves visual acuity in 95% of cases.

Figure 15.1

Cortical cataract. Slit-lamp photograph of a 69-year-old man's left eye shows nuclear and cortical changes to the lens consistent with a cataract. The patient had a 2-year history of ↓ visual acuity. (Reproduced with permission from USMLE-Rx.com.)

Figure 15.2

Vision with cataract. (Reproduced from the National Eye Institute.)

Glaucoma

A group of disorders characterized by ↑ intraocular pressure, leading to irreversible damage to the optic nerve.

Open-Angle Glaucoma

↑ intraocular pressure due to abnormal aqueous drainage through the trabecular meshwork of the eye (Figures 15.3 and 15.4). The most common form of glaucoma, accounting for >90% of cases. Prevalence is ↑ in first-degree relatives of affected individuals and in persons with diabetes. May also develop after uveitis or trauma. Risk factors include age >65 years, ⊕ family history of glaucoma, black ancestry, and diabetes.

Figure 15.3

Pathophysiology of open-angle glaucoma. The fluid leaves the chamber at the open angle where the cornea and iris meet. When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye. (Reproduced from the National Eye Institute.)

Figure 15.4

Glaucoma. Color fundus photograph of a 65-year-old man's left eye shows a left optic nerve with glaucomatous cupping and peripapillary atrophy. The patient had elevated intraocular pressure. (Reproduced with permission from USMLE-Rx.com.)

Symptoms

  • Insidious onset; patients are often asymptomatic until vision is seriously compromised; painless.

  • Characterized by bilateral peripheral vision loss, leading to ↑ tunnel vision (Figure 15.5).

  • Patients may also complain of “halos around lights.”

Figure 15.5

Vision with glaucoma. (Reproduced from the National Eye Institute.)

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