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LOW VISION DEVICES
What Is Low Vision?
Low vision is diminished sight with minimal ability to see (particularly central vision) that is unresolved or uncorrected with traditional eye glasses, contact lens, intraocular lens implants, or corrective surgery. However, in some cases, persons with low vision may be aided with special visual devices.
Causes of Low Vision:
- Macular degeneration is the most common cause of low vision. It involves damage to the macula, thereby affecting central vision and making it difficult for a person to read, drive, or perform other daily activities that require fine, central vision.
- Aging is a risk factor for low vision. However, persons of any age may be affected.
- Congenital defects present at birth.
- Injury to the eye or brain.
- Diseases like diabetes, glaucoma etc.
Different Types of Low Vision:
- Visual disability (6/18, 6/24, 6/36)
- Economic blindness (6/60, 5/60, 4/60)
- Social blindness (3/60, 2/60, 1/60)
- Total blindness (CF, HM, PL)
Management of Low Vision
It involves three steps:
- Evaluation
- Prescription of low vision devices
- Rehabilitation
Low Vision Evaluation:
Low vision evaluation is a process that helps to assess the visual needs of a person with low vision. An ophthalmologist or optometrist, who specializes in low vision, performs a comprehensive visual function evaluation using special charts. After thorough examination the ophthalmologist gives advice on:
- Optimum use of vision
- The low vision devices required and their usage.
- The best adaptation to home, school, the workplace and nearby surroundings.
Low Vision Devices
Because low vision cannot be improved by traditional methods (i.e., the use of eyeglasses, contact lenses, etc.) persons with low vision often rely on the use of a number of different instruments, called low vision devices, and tailored equipment for improved vision. Low vision devices can be of two types:
Optical
Non-optical
These devices help people with low vision in enhancing their residual vision.
Optical low vision devices
Simply stated, optical low vision devices involve the use of many types of lenses to improve vision. For example:
- Filter lenses to control glare.
- Telescopes that are used for distance vision functions like seeing signs and faces, reading blackboard or watching television.
- High powered magnifying spectacles, hand held magnifiers and stand magnifiers for the purpose of reading and writing.
- Non optical devices like special lamps, reading stands & large reading materials.
- Electronic magnifiers, close circuit televisions and video magnifiers.
Non-optical low vision devices:
Non-optical low vision devices help bring images closer to the eyes. This may include the use of any, or all, of the following:
- Larger print items (i.e., magazines, newspapers, books, calendars, address books, cookbooks, dictionaries, games, playing cards, sheet music, street signs, etc.).
- Larger, illuminated watches and clocks writing guides.
- Instruments that provide voice instruction (i.e., computers).
- Instruments that provide voice information (i.e., clocks, timers, calculators, scales, key chains, etc.)
Low Vision Clinic at Ratan Jyoti Netralaya Provides:
- Clinical low vision examination.
- Functional low vision examination.
- Visual function evaluation of children with special needs.
- Prescription and training in use of low vision devices.
- Counseling for visual rehabilitation.
- Individual vision training programmes.
- Referrals for orientation and mobility assessment.
- Follow – up at home and in school.
- Counseling and setting for environmental modifications.
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