MyVisionTest News Archive
May 27, 2008
The Visually Impaired Patient
Blindness is one of the most feared illnesses by Americans, ranking fourth after AIDS, cancer, and Alzheimer's disease. The National Eye Institute reports that blindness or low vision affects 3.3 million Americans 40 years and older; this number is projected to reach 5.5 million by 2020. As the U.S. population ages, the number of persons with major eye disease is increasing. Octogenarians currently make up 8 percent of the population, but they account for 69 percent of blindness. Age-related macular degeneration (AMD) accounts for 54 percent of all blindness and is the leading cause of blindness among white Americans.
Low vision ranks behind arthritis and heart disease as the third most common chronic cause of impaired function in persons older than 70 years. Patients with vision impairment are more likely to fall, make medication errors, have depression, or report social isolation. With rehabilitation, many patients with impaired vision can attain independence, retain their jobs, and lessen their reliance on social services and institutions.
Low vision is not a diagnosis, but a result of an eye condition that causes reduced visual function. In the United States, the most prevalent etiologies of vision loss in persons 40 years and older are AMD, glaucoma, cataracts, and diabetic retinopathy.
Patients with AMD may be initially asymptomatic, progressing to a loss of central vision (reduced visual acuity causing difficulties with detail discrimination) accompanied by metamorphopsia (distortion of objects), central scotomas, increased glare sensitivity, decreased contrast sensitivity, and decreased color vision. Peripheral vision remains intact, and the patient does not progress to total blindness. Although the etiology of AMD is unclear, older age, smoking, hypertension, hyperlipidemia, vascular insufficiency to the retina and the choroids, a history of ultraviolet (UV) light exposure, and a family history of AMD (which increases risk three- to fourfold) are known contributing factors. Persons with early disease who continue to smoke are at increased risk of vision loss compared with those who stop smoking. Patients with nonexudative AMD should be monitored by an eye care specialist; if neovascularization develops, photodynamic therapy and intravitreal injections of antivascular endothelial growth factor and corticosteroids have proved to be useful.
The Age-Related Eye Disease Study showed that patients with intermediate AMD or advanced AMD in one eye but not the other have a 25 percent lower risk of developing advanced AMD and a 19 percent lower risk of developing vision loss caused by advanced AMD when treated with a high-dose regimen of vitamin C, vitamin E, beta carotene, and zinc. Patients without AMD and those with early AMD did not benefit from supplementation. Other strategies include control of vascular disease risk factors, exercise to increase circulation, and sunglasses for UV light protection.
In addition to specific disease prevention and treatment, some patients may benefit from vision-enhancing devices. The devices are task specific, and physicians should consider the patients' needs and motivation to learn and practice using the device, as well as any physical limitations. Although these devices are not covered by most insurance companies, they may be provided free if patients meet the eligibility requirements of their state Commission for the Blind.
One of the more commonly prescribed devices is the high-powered prismatic spectacle. These eyeglasses enable a patient to read while providing a socially acceptable form of vision correction. Another aid is the handheld magnifier, which enables a patient to hold reading material farther from the eyes. Stand magnifiers may be more beneficial to patients with physical limitations, such as hand tremors, that prevent them from holding a device or reading material.
Telemicroscopes are spectacle-mounted telescopes that are focused for reading or viewing material at arm's length. They are ideal for activities such as painting, reading music, and viewing a computer monitor. Telescopes, either handheld or spectacle mounted, are useful for viewing objects in the distance such as television screens and street signs. In some states, these devices may be used for driving if a patient meets certain visual requirements. Video magnifiers and closed circuit televisions use video cameras to enhance and magnify material on a monitor. These devices can magnify up to 60 times and allow space for writing. Large print computer software and voice synthesizers that speak the words that appear on the screen can allow visually impaired patients to use computers and access the Internet.
Nonoptical devices can be equally useful in low vision rehabilitation. Special filters can help reduce glare and enhance contrast, which are critical to reading. Bright reading lamps, check-writing guides, and wide point felt-tipped pens can help patients pay bills and write. Large-print materials (e.g., books, telephone dials, clocks, watches), audiobooks, and "talking" devices (e.g., clocks, glucometers) are also available.
A key factor in the use of vision enhancing devices is that considerable practice is required to use them effectively. Reading with a vision-enhancing device is not the same as reading before the vision loss. If a patient is willing to relearn tasks, he or she will benefit by becoming more confident and functionally independent.
Read more...
RedOrbit
Tags: AMD, low vision
Blindness is one of the most feared illnesses by Americans, ranking fourth after AIDS, cancer, and Alzheimer's disease. The National Eye Institute reports that blindness or low vision affects 3.3 million Americans 40 years and older; this number is projected to reach 5.5 million by 2020. As the U.S. population ages, the number of persons with major eye disease is increasing. Octogenarians currently make up 8 percent of the population, but they account for 69 percent of blindness. Age-related macular degeneration (AMD) accounts for 54 percent of all blindness and is the leading cause of blindness among white Americans. Low vision ranks behind arthritis and heart disease as the third most common chronic cause of impaired function in persons older than 70 years. Patients with vision impairment are more likely to fall, make medication errors, have depression, or report social isolation. With rehabilitation, many patients with impaired vision can attain independence, retain their jobs, and lessen their reliance on social services and institutions.
Patients with AMD may be initially asymptomatic, progressing to a loss of central vision (reduced visual acuity causing difficulties with detail discrimination) accompanied by metamorphopsia (distortion of objects), central scotomas, increased glare sensitivity, decreased contrast sensitivity, and decreased color vision. Peripheral vision remains intact, and the patient does not progress to total blindness. Although the etiology of AMD is unclear, older age, smoking, hypertension, hyperlipidemia, vascular insufficiency to the retina and the choroids, a history of ultraviolet (UV) light exposure, and a family history of AMD (which increases risk three- to fourfold) are known contributing factors. Persons with early disease who continue to smoke are at increased risk of vision loss compared with those who stop smoking. Patients with nonexudative AMD should be monitored by an eye care specialist; if neovascularization develops, photodynamic therapy and intravitreal injections of antivascular endothelial growth factor and corticosteroids have proved to be useful.
The Age-Related Eye Disease Study showed that patients with intermediate AMD or advanced AMD in one eye but not the other have a 25 percent lower risk of developing advanced AMD and a 19 percent lower risk of developing vision loss caused by advanced AMD when treated with a high-dose regimen of vitamin C, vitamin E, beta carotene, and zinc. Patients without AMD and those with early AMD did not benefit from supplementation. Other strategies include control of vascular disease risk factors, exercise to increase circulation, and sunglasses for UV light protection.
In addition to specific disease prevention and treatment, some patients may benefit from vision-enhancing devices. The devices are task specific, and physicians should consider the patients' needs and motivation to learn and practice using the device, as well as any physical limitations. Although these devices are not covered by most insurance companies, they may be provided free if patients meet the eligibility requirements of their state Commission for the Blind.
One of the more commonly prescribed devices is the high-powered prismatic spectacle. These eyeglasses enable a patient to read while providing a socially acceptable form of vision correction. Another aid is the handheld magnifier, which enables a patient to hold reading material farther from the eyes. Stand magnifiers may be more beneficial to patients with physical limitations, such as hand tremors, that prevent them from holding a device or reading material.
Telemicroscopes are spectacle-mounted telescopes that are focused for reading or viewing material at arm's length. They are ideal for activities such as painting, reading music, and viewing a computer monitor. Telescopes, either handheld or spectacle mounted, are useful for viewing objects in the distance such as television screens and street signs. In some states, these devices may be used for driving if a patient meets certain visual requirements. Video magnifiers and closed circuit televisions use video cameras to enhance and magnify material on a monitor. These devices can magnify up to 60 times and allow space for writing. Large print computer software and voice synthesizers that speak the words that appear on the screen can allow visually impaired patients to use computers and access the Internet.
Nonoptical devices can be equally useful in low vision rehabilitation. Special filters can help reduce glare and enhance contrast, which are critical to reading. Bright reading lamps, check-writing guides, and wide point felt-tipped pens can help patients pay bills and write. Large-print materials (e.g., books, telephone dials, clocks, watches), audiobooks, and "talking" devices (e.g., clocks, glucometers) are also available.
A key factor in the use of vision enhancing devices is that considerable practice is required to use them effectively. Reading with a vision-enhancing device is not the same as reading before the vision loss. If a patient is willing to relearn tasks, he or she will benefit by becoming more confident and functionally independent.
Read more...
RedOrbit
