What is Legal Blindness?
Most people have heard of the term “legally blind” but do not actually know what it means. Most people use this term to describe their eyesight without the use of visual aids like glasses or corrective contact lenses. Others assume that it is a synonym for total blindness. Neither of these is true. Legal blindness is actually a level of visual impairment that is defined by law that limits allowed activities for safety reasons. It can also be used to determine eligibility for government-funded disability benefits.
There are two types of legal blindness as defined by the U.S. Social Security Administration. Legal blindness due to reduced visual acuity and legal blindness due to visual field restriction.
Reduced Visual Acuity
In the United States, we use the 20/20 Snellen System to test visual acuity. Visual acuity tests measure your central vision. If you have perfect vision (20/20) this means that the smallest letters that a person can see from a distance of 20 feet are the same size as someone with normal vision can see from a distance of 20 feet. In order to be considered legally blind, the visual acuity in your better eye, while you are wearing corrective lenses, must be 20/200 or worse. If your vision can be corrected with lenses to be better than 20/200, you are not considered legally blind.
Visual Field Restriction
The visual field restriction tests to see how wide your visual field is. Some people who have a great central vision, cannot notice someone right next to them in their peripheral vision. People with normal peripheral vision have a maximum lateral field of view that is close to 180 degrees. If your peripheral view is restricted to 20 degrees, then you are considered legally blind.
Causes of Legal Blindness?
There are four leading causes of legal blindness in the United States. These are:
- Age-related macular degeneration
- Diabetic retinopathy
If you have one of these eye conditions, it is important that you get regular eye examinations with your ophthalmologist at the Boston Eye Group.
For people who are legally blind, there are many resources available to them to assist in their daily lives. If you have any questions concerning legal blindness contact Boston Eye Group. Our eye care specialists are available to help you find any resources that you may need.