Low vision is a visual
impairment, not total vision blindness, which results in a permanent
decrease in the acuity of an individual's vision field. Unlike normal vision
impairments such as nearsightedness and farsightedness, low vision can't be
fully corrected by using standard vision aids such as eyeglasses or contacts.
According to the Association for the Blind and Visually Impaired (ABVI), an
individual has low vision when "the better-seeing eye will not reach visual
acuity of 20/70 or greater after the strongest correction aid is applied".
This guide will help you understand and be able to identify the early
warning signs of low vision, along with the resources available to help
individuals with low vision accomplish a variety of everyday tasks.
Common conditions that result in low vision include cataracts,
stroke, glaucoma, macular degeneration, diabetic retinopathy and retinal
detachment. The five most common types of low vision, as defined by
the American Optometric Association/1, are as follows:
- Loss of Central Vision – The loss of central vision
creates a blur or blind spot, but side (peripheral) vision remains intact. This
makes it difficult to read, recognize faces, and distinguish most details in
the distance. Mobility, however, is usually unaffected because side vision
- Loss of Peripheral (Side) Vision –
This vision loss is often referred to as "tunnel vision" and is the result
of the inability to distinguish anything to the one side or both sides of a
vision field, or anything directly above and/or below the eye level.
Central vision will remain acute, making it possible to see directly
- Extreme Light Sensitivity – This vision
impairment exists when standard levels of illumination overwhelm the visual
system, producing a washed out image and/or glare disability. People with
extreme light sensitivity may actually suffer pain or discomfort from
relatively normal levels of illumination.
Blindness – This results in the inability to see outside at night
under natural illumination such as moonlight, or in dimly lighted interior
areas such as movie theaters or restaurants.
Vision – A general blurriness across the entire vision field
causes objects, both near and far, to appear out of focus, even when the
best correctional device is applied.
Early warning signs of low
vision include difficulty recognizing objects up close or at a distance,
differentiating between colors, and overall blurry vision. Individuals,
through their primary eye care provider, should contact a Low Vision Eye
Care Specialist who can perform a unique eye examination called a low
vision evaluation. This type of examination involves a multitude of tests
that assess the range of the vision field, ocular perception and
sensitivity, assessment of any ocular injury or disease, and overall
mobility of the eye. After this series of tests, the low-vision specialist
will perform tests with various telescopic and magnification aids to
determine which low-vision aid will provide the best visual field
Speaking with a low-vision specialist about
rehabilitation services and useful tips to overcome everyday challenges will
greatly increase the success of living with low vision.
There are a
large number of vision aids available to individuals with low vision and
based on the ocular evaluation, a low-vision specialist may prescribe a
single low-vision device or a combination of visual devices. Some low-vision
adaption devices include magnifying glasses, large print objects (i.e.
books, phones), and talking devices that speak simple information such as
the time, date and directions. The most common low-vision aid is absorptive
lenses that are worn over prescription eyeglasses to eliminate harmful
sunlight. Absorptive lenses increase the contrast of objects and help
individuals when transitioning between light and dark surroundings.
Other devices such as closed circuit magnifiers, lens-mounted magnifiers,
and reading machines, are used in rare occasions when low vision severely
impairs an individual's vision field. A closed-circuit magnifier is a
specialized video camera that magnifies an object more intensely than
standardized magnifiers, and projects the image onto a screen such as a
television or computer screen. Lens-mounted magnifiers are a small tool that
combines the magnification powers of a microscope and telescope, and allow
the ability to magnify objects up close and improve distance vision.
Speaking with a low-vision specialist about rehabilitation services and
useful tips to overcome everyday challenges will greatly increase the
success of living with low vision. Family and friends are also valuable
resources and can provide assistance when facing challenging tasks. By
using available resources and with the help of low-vision aids,
individuals with low vision continue to lead independent and fulfilling