Significant visual impairment that cannot be corrected with standard glasses, contact lenses, medicine or eye surgery. Low vision includes loss of best-corrected visual acuity – to a level worse than 20/60 in the better eye, measured with a standard eye chart – or visual field loss such as tunnel visionor blind spots. It also describes legal blindness and almost total blindness. Low vision has a variety of causes, including eye injury, diseases and heredity. Sometimes low vision involves a lack of acuity, meaning that objects appear blurred. Other times, it involves a significant loss of peripheral vision and visual field. Other symptoms of low vision include light sensitivity, distorted vision or loss of contrast. The eyesight of a person with low vision may be hazy from cataracts, blurred or partially obscured in the central visual zone because of macular degeneration or distorted and/or blurred from diabetic retinopathy.
Also, people with glaucoma or retinitis pigmentosa can lose their peripheral vision and have difficulty seeing at night. Children as well as adults can be visually impaired, sometimes as a result of a birth defect or an injury. But low vision more commonly afflicts adults and seniors. Vision loss can be very traumatic, leading to frustration and depression. Many people who develop eye problems that cause low vision lose their jobs, not being able to drive safely, read quickly or easily see images on a television or computer screen can cause people with low vision to feel shut off from the world. They may be unable to get around town independently, earn a living or even shop for food and other necessities.
Many low vision devices can make reading easier and more rewarding for people with macular degeneration, retinitis pigmentosa, tunnel vision and other low vision conditions. The most affordable are hand-held magnifiers, some of which contain small reading lamps for better illumination. Other magnifiers are mounted on height-adjustable stands or hang around the neck. Strong reading glasses come in full or half-lens styles. Or you can obtain bifocals with high-power reading lens segments. Reading telescopes are another option. They can be hand-held or mounted onto special eye-glass frames with enhanced nose pads and padded bridges, so your nose will carry the weight more comfortably.
Video magnifiers project printed material on a Closed Circuit Television (CCTV) monitor or regular television or computer screen; you can sit as close to the screen as necessary and adjust the magnification, brightness, contrast and color of the display to your liking. Some reading devices require a prescription from your eye care practitioner because they are custom-made for your particular needs. But consult your doctor before buying even nonprescription magnifiers, because he or she can tell you which low vision devices will work best for you, based on your activities and the lens power you require.
Good Lighting Is Essential
For many people with low vision, increasing the amount and type of ambient light can greatly improve reading ability. If you know someone who is visually impaired, check the adequacy of the lighting in their home – particularly in their favorite reading areas. Use the brightest light bulbs recommended for light fixtures. Natural sunlight is the best lighting for reading. Arrange furniture so the person with low vision can sit near a window for daytime reading. For artificial lighting, purchase “full-spectrum” light bulbs. These bulbs emit light that more closely mimics natural sunlight than regular incandescent bulbs.
Avoid harsh fluorescent lighting, which can cause glare – especially for anyone with low vision. Replace fluorescent desk lamps or kitchen lighting with halogen task lighting or full-spectrum bulbs for better comfort and visibility. In addition to low vision devices and good lighting, inexpensive non-optical adaptive aids can assist with routine daily activities
Anyone with reduced vision not corrected by spectacles or contact lenses can be considered to be visually impaired. The World Health Organization uses the following classifications of visual impairment. When the vision in the better eye with best possible glasses correction is:
- 20/30 to 20/60 : is considered mild vision loss, or near-normal vision
- 20/70 to 20/160 : is considered moderate visual impairment, or moderate low vision legal blindness
- 20/200 to 20/400 : is considered severe visual impairment, or severe low vision
- 20/500 to 20/1,000 : is considered profound visual impairment, or profound low vision
- More Than 20/1,000 : is considered near-total visual impairment, or near total blindness
Information Is Fundamental:
Doctors and sanitary personnel must have this information to offer the patient when the moment is right. The desolation that doctors experience when they must tell a patient they can’t do anything more is only surpassed by the loneliness and isolation the patient, who does not know where to go or what to do for help. Administrative aids are valuable allies, though sometimes they may lie hidden under a legal mess. Adaptation to the disability and psychological help are priority-one issues and must be confronted from the start. Not least important and almost as urgent is the education of the patient and their family to confront the new situation. The adaptation of the work place (the one the person currently has or a different one) is regulated by laws and norms and there are interesting subventions for companies that make the necessary modifications to allow a person with disabilities into their work force; therefore the reluctance to hire visually handicapped people is an anti-economic prejudice, for the company and society. Lastly, social integration aids facilitate adapted leisure and cultural activities, and private and public initiatives tending to improve mobility and better access to information for everybody, including the visually impaired.
Optical Aids
The vast majority of patients with low vision can be helped to function at a higher level with the use of low vision devices. Low vision specialists recommend appropriate low vision devices and counsel patients on how better to deal with their reduced vision in general. Many government and private organizations exist to aid the visually impaired.
Improving Far Sight:
Works best with static objects
- TV
- Theater
- Cinema
- Contemplating scenery
- Seeing the bus number
Improving Near Sight:
The person must work closer to the object
- Reading
- Writing
- Crafts
Improving Sensitivity To Contrast:
The person must use special optical filters
Other Tools:
- Book stands
- Special lights
- Grid paper
- Magnified games
- Watches, audio thermometers, special phones, etc