
Adaptive Technology
Electronic magnification systems like closedcircuit TVs (CCTVs) and
computers.
Amsler Grid
A test for determining potential changes in central vision and the
level of impairment due to those changes. It is often used to detect and
follow AMD.
Binocular
Using both eyes; also, a device designed for use with both eyes.
Legal blindness is different.
Blindness
The term "blindness" or "blind" should be reserved for individuals who are actually blind, meaning that they have no light perception or those who have so little vision that they rely mostly on other senses (this is known as "vision subsitute skills"). Even very slight light perception can serve to increase orientation and mobility in a patient.Legal blindness is different.
Contrast Sensitivity
The ability to detect differences in grayness and background. There are
special tests to measure the loss of contrast which are useful in prescribing optical
and non-optical devices and strategies for independent function.
Depth Perception
The ability to determine how far away an object is.
Eccentric Viewing
Not looking directly at an object, but rather learning to focus an image
onto a healthier part of the retina. This is used when central vision has been
diminished.
Functional Blindness
Describes the condition of an individual who has no useful vision.Functional Vision
Vision loss defined in terms of the individual’s abilities with regard to activities of daily living such as reading, orientation in space and mobility. Functional vision describes the way an individual is able to live his or her day to day life and does not describe the function of one or both of his or her eyes.Functional Vision Loss
How vision loss affects the ability to function and perform activities
of daily living.
Legal Blindness
In the United
States and Canada, “legal blindness” is defined as visual acuity with
best correction in the better eye worse or equal to 6/60 (20/200), or a visual
field extent of less than 20 degrees in diameter.
The term “legal
blindness” is a arbitrary definition and it has little value for vision rehabilitiation. Many legally blind people can lead rich and functional lives with the help of low vision rehabilitation. The definition of legal blindness is important for determining ability to drive and eligibility for government programs.
Low Vision Services
The examination and accompanying education that lead to and determine
what devices will be prescribed.
Monocular
Using one eye; also a device intended for use with one eye.
Orientation and Mobility
Training to help the partially-sighted get around as safely and as
independently as possible.
Peripheral Vision
Ability to see objects that are not in the direct line of vision.
Photophobia
Discomfort and/or sensitivity to light.
Severe Vision Impairment
An inability to recognize a friend at
arm’s length even when wearing glasses or contact lenses, or an inability to read
ordinary newspaper print even when wearing glasses or contact lenses, or
reports poor or very poor vision even when wearing glasses or contact lenses,
or is blind in both eyes.
Severe visual impairment is a condition where best-corrected visual acuity is less than 6/48 (20/160), including 6/60 (20/200), to 3/60 (20/400), or the visual field diameter is 20 degrees or less (largest field diameter for Goldmann isopter III4e, 3/100 white test object, or equivalent). Severe visual impairment in both eyes is the minimum requirement to be considered legally blind.
Severe visual impairment is a condition where best-corrected visual acuity is less than 6/48 (20/160), including 6/60 (20/200), to 3/60 (20/400), or the visual field diameter is 20 degrees or less (largest field diameter for Goldmann isopter III4e, 3/100 white test object, or equivalent). Severe visual impairment in both eyes is the minimum requirement to be considered legally blind.
Visual Acuity
The ability to see detail (see definition of Legal Blindness).
Visual Impairment
Vision loss defined in terms of the function of the eye. Examples are visual acuity loss or visual field loss. An individual can have visual impairment in one eye, while the other eye is normal.Visual Field
The space in which objects are visible when the eye is in a fixed
position.
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