Complex Visual Hallucinations and Macular Degeneration :: Optometry Psychiatry Neurology Essays

Complex Visual Hallucinations and Macular DegenerationLocated in the eye of the retina, the sensitive macula provides us with sight in the center of our field of reverie. When we look directly at something, the macula allows us to ascertain the fine details. This sharp, straight-ahead flock is necessary for driving, reading, recognizing faces, and doing close work, such as sewing. Macular depravation is the impairment of this central macular area. Age-related macular degeneration (AMD) is the most common cause of vision loss in the Western world in the over 50 get along group. It most commonly affects those of northern European descent and is extraordinary in Afri burn down-Americans and Hispanics. The prevalence increases with age. It affects about 15% of the population by age 55, and over 30% are affected by age 75 (Miller, 1992).In macular degeneration a layer beneath the retina, called the retinal rouge epithelium (RPE), gradually wears out from its lifelong duties of dis posing of retinal waste products. eventually the capacity of the RPE layer to handle these metabolic products is overwhelmed and the RPE begins to degenerate (Miller, 1992). Other thickset layers involved in development of macular degeneration are Bruchs membrane and the choroid layer. Additional factors that whitethorn hasten loss of the RPE layer, and the resulting degeneration of the central retina (macula) implicate hereditary factors, ultraviolet rays from sunlight, and blue iris color (more UV rays make the retina in blue-eyed patients, probably because of the lower hue density in the eye).There are basically two formulates of macular degeneration. So-called dry (or atrophic) macular degeneration, which accounts for 90% of cases, is caused by the aging and thinning of the tissues of the macula (Miller, 1992). This type is characterized by trivial yellowish deposits under the macular part of the retina. These deposits are known as drusen and may increase in size and numb er over time. Areas of loss of retinal and RPE layers in the macula may gradually appear. Small clumps of brown pigment from the degenerating RPE layer also are commonly seen.The other major form of this disease is wet (or exudative macular degeneration) which is a much greater threat to vision loss even though it accounts for only 10% of cases. This type can be associated with a more sudden loss of vision receivable to leakage or bleeding under the macula from abnormal vessels, called the choriocapillaris, arising from ane of the deeper layers.