Someone is legally blind if their central vision in their better eye is 20/200 or less, even with correction. If you have blindness, you must be 20 feet or closer to see something a person with regular vision can see 200 feet away.
Blindness is a lack of vision or a loss of vision that can’t be corrected. Partial blindness indicates limited vision, while complete blindness indicates you can’t see anything, including light.
The United States’ legal definition of blindness has existed since the mid-1930s. This definition helps establish a level of vision loss that might result in the inability to perform certain everyday tasks without assistance.
The legal definition of legal blindness is: “Central visual acuity of 20/200 or less in the better eye with the use of correcting lens. An eye which has a limitation in the field of vision so that the widest diameter of the visual field subtends an angle no greater than 20 degrees is considered to have a central visual acuity of 20/200 or less.”
This means that even with corrective lenses or surgery, to see an object that a person with typical vision could see from 200 feet away, a legally blind person would have to be 20 feet or closer.
A person is considered to have low vision or visual impairment if their best corrected vision is
Functional vision loss (FVL), also called
FVL is considered within the spectrum of conversion disorder.
Vision impairment can take on many forms.
Central vision loss
Most of your detail vision is in the center of your visual field. You use central vision to read. When a loss of this detail vision occurs, you’re said to have central vision loss.
Eye conditions that may interfere with your central vision include:
Tunnel vision
With tunnel vision, you can see the central part of your vision but not the periphery. Tunnel vision interferes with travel vision more than it does with reading vision.
Eye conditions that may cause tunnel vision include:
Blind spots
Some people have vision with blind spots. Traces of blood in the vitreous fluid in the eye that block certain areas may cause blind spots. The amount and location of vision impairment may change daily.
Conditions that may cause blind spots include:
- diabetic retinopathy
- inflammation of the optic nerve
Partial vision
Also known as low vision or reduced vision, partial vision varies from person to person, depending on factors such as:
Some people with partial vision could be considered legally blind. Conditions that may cause partial vision include:
- cataracts
- retinitis pigmentosa
retinopathy of prematurity
Total blindness
People with total blindness have no light perception.
Conditions that can cause total blindness include:
Although we think of blindness as total blindness, legal definitions in the United States describe varying degrees.
These definitions, including being legally blind, detail a level of vision loss that, even with correction, requires assistance with certain everyday tasks.