“Legally blind” is a classification used for administrative purposes, distinct from total blindness or general vision impairment. This term defines a specific level of visual function, enabling individuals to access various forms of support and resources. It is not a medical diagnosis of an eye condition itself, but rather a standardized definition for eligibility for certain programs and benefits.
What Legal Blindness Means
The designation of legal blindness defines a significant level of visual impairment that qualifies an individual for specific accommodations, services, and benefits. This classification can unlock opportunities such as vocational training, rehabilitation services, schooling accommodations, disability benefits, and tax exemptions. It provides a clear threshold for determining who can receive assistance tailored to profound visual limitations.
Specific Visual Acuity and Field Criteria
In the United States, legal blindness is defined by specific criteria related to visual acuity and visual field. One primary criterion is a central visual acuity of 20/200 or less in the better eye, even with the best conventional correction, such as glasses or contact lenses. To understand 20/200 vision, a person with normal 20/20 vision can clearly see an object from 200 feet away, while someone with 20/200 vision must be as close as 20 feet to see that same object clearly.
Alternatively, an individual may be considered legally blind if they have a visual field of 20 degrees or less in the better eye. This refers to the total area one can see when looking straight ahead, encompassing peripheral vision. A restriction to 20 degrees or less means a severely narrowed scope of vision, often described as “tunnel vision.” Meeting either the visual acuity or the visual field criterion is sufficient for a legal blindness classification. These criteria are established by federal law, notably through the Social Security Act, for disability purposes.
How Legal Blindness is Determined
The official determination of legal blindness involves a thorough examination by a qualified eye care professional, such as an ophthalmologist or optometrist. This process includes specific tests designed to measure both central visual acuity and the extent of the visual field.
A common test for visual acuity is the Snellen chart, which features rows of letters that decrease in size. The eye care professional measures the smallest line an individual can read from a standard distance while wearing their best corrective lenses. For assessing the visual field, perimetry tests are used, which can include a confrontational visual field test or more advanced automated visual field tests. These tests map the scope of an individual’s peripheral vision. Accurate documentation of these test results is essential for certifying legal blindness, often involving specific forms or reports required by administrative bodies.
Common Misconceptions
A prevalent misconception is that “legally blind” means an individual cannot see anything at all. This is inaccurate, as total blindness, or “no light perception,” is a complete inability to perceive light. In reality, most legally blind individuals retain some usable vision, perceiving light, shapes, and even colors, though with significantly reduced clarity. The range of vision among them is broad; some have blurry central vision, while others have a constricted field of vision, seeing clearly only through a small central area. This classification acknowledges a severe degree of vision loss that warrants specific support, recognizing that individuals often navigate the world with remaining, albeit limited, visual function.