Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Social Security Administration SSA to determine if someone is eligible to receive disability benefits, tax exemptions, and low vision training. The terms also may be used by health insurers to determine benefits and as part of vision screening tests required by state departments of motor vehicles DMVs in determining driver's license eligibility.
According to the American Foundation for the Blind,legally blind is not the same as totally blind, which is used to describe the inability to see anything at all out of either eye. Most people who are legally blind have some vision.
To be considered legally blind, you would have to meet one of two criteria for visual acuity sharpness of vision and visual field the entire scope of what you can see without moving your eyes. Visual acuity refers to how close a person needs to be to an object that's 20 feet away in order to see it in detail. More than 4. If a person has a visual field of only 20 degrees, they can see things that are right in front of them without moving their eyes from side to side but they can't see anything on either side peripheral vision.
A visual field of degrees is considered normal. A severely limited visual field sometimes is called tunnel vision. It makes it nearly impossible to drive safely. An eye doctor will measure visual acuity and visual field to determine if a person is legally blind.
A common test for visual acuity is the Snellen eye chart. Someone who is legally blind would be able to read only the top line of the chart, a capital E while wearing corrective lenses. Visual field testing often begins with a confrontational visual field test in which you an eye doctor has you cover one eye at a time and then holds up one or more fingers in different quadrants of the visual field to see if you can see them while keeping your eyes focused on a central point in front of you.
There are also more comprehensive computerized tests that use flashing, flickering, or moving lights or images to measure your visual field. It involves pressing a button when you see the light or images. How do I fix eye vision? I have myopia, I'm What age of a person has particularly good night vision? Which types of corrective eye surgery are best suited for farsightedness hyperopia?
How did you hear about us? Other Information Lic View all posts by: innexus. What Does it Mean to be Legally Blind? Written by innexus View all posts by: innexus. Office Hours Mon day am pm Tues day am pm Wed nesday am pm Thurs day am pm Fri day am pm Sat urday am pm Sun day Closed.
Glaucoma — Damage to the retina caused by high fluid pressure inside the eye. Optic neuritis and neuropathy — Damage to the pathway between the eyes and the brain optic nerve or the sheath around it.
Congenital glaucoma — A rare form of retinal damage diagnosed at birth or within the first few years of life. Retinopathy of prematurity — Disruption of retinal growth that usually affects babies born prematurely with a low birth weight.
Keratoconus — A gradual thinning of the cornea. This describes legal blindness due to poor peripheral vision. A wide field of vision is critical for activities like driving a car or crossing a busy street. Visual field tests can determine if you have a normal field of view without any blind spots or unusual narrowing of your peripheral vision. Peripheral vision has two components: lateral side to side and vertical up and down. The maximum lateral field of view is almost degrees — half of a complete circle — and the observer can see distant objects on both sides of their vision.
0コメント