Chapter 6 Special Sensory Organs: Eye and Ear 261 Diabetic Retinopathy Diabetic retinopathy (RĔT-ĭ-NŎP-ă-thē) is a serious complication of dia- betes marked by progressive damage to the blood vessels of the retina. It is a chronic condition that can develop in patients with uncontrolled diabetes. In the early stages of diabetic retinopathy, patients are often asymptomatic (with- out symptoms). As the condition progresses, it may result in blurred or fluctu- ating vision (sight that “comes and goes”), floaters (small spots or specks that float around in the field of vision), dark or empty areas in the vision, or dif- ficulty with color perception. Typically, diabetic retinopathy affects both eyes. Glaucoma Glaucoma (glaw-KŌ-mă) is a group of eye conditions that cause optic nerve damage, which may lead to loss of vision. The optic nerve carries visual information from the eye to the brain. In most cases, damage to this nerve is the result of abnormally high intraocular pressure (IOP), or pressure within the eye. Because glaucoma damage is gradual, the patient may not notice any loss of vision until the disease has reached an advanced stage. Glaucoma is a major cause of blindness in the United States. Macular Degeneration Macular degeneration is a leading cause of vision loss among Americans 60 years of age and older. In macular degeneration, the central portion of the retina, called the macular area, degenerates over time, resulting in loss of central vision (Figure 6.6). Varying degrees of peripheral vision remain, but those afflicted with macular degeneration are often unable to read or drive, and other activities of daily living are severely restricted due to the loss of full, clear vision. How a scene appears with normal vision How a scene appears with vision affected by macular degeneration Photo credit: Smereka/Shutterstock.com. Concept adapted from Lighthouse International http://lighthouse.org/about-low-vision-blindness/vision-disorders/age-related-macular-degeneration-amd/ Figure 6.6 Macular degeneration
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