The Social Security Administration published new rules for visual disorders in the Federal Register (71 FR 67037) on November 20, 2006. These rules became effective on February 20, 2007.
As in the past, statutory/legal blindness continues to be defined as best corrected visual acuity of 20/200 or less in the better eye; or a visual field limitation such that the widest diameter of the visual field, in the better eye, subtends an angle no greater than 20 degrees, as measured with a Goldmann III4e or equivalent size stimulus.
Under the new rules, how visual acuity and visual field can be tested to meet this definition has changed.
For visual field testing, the following measurements can be used:
- Automated static threshold perimetry (Humphrey 30-2 and 24-2)
a. For Humphrey Field Analyzers, a 10dB stimulus is equivalent to a 4e stimulus. A dB level that is higher than 10 represents a dimmer stimulus, while a dB level that is lower than 10 represents a brighter stimulus. Therefore, for automated static threshold tests performed on Humphrey Field Analyzers, any point seen at 10dB or higher are a point that would be seen with a 4e stimulus.
- Kinetic perimetry, such as the Humphrey "SSA Test Kinetic"
a. The kinetic test must use a white III4e stimulus projected on a white 31.5 apostilb (10 cd/m2) background.
- Goldmann perimetry
a. With a III4e target.
SSA will not use the results of visual field screening tests, such as confrontation tests, tangent screen tests, or automated static screening tests, to determine legal blindness.
For visual acuity testing, the criteria changed because most test charts that use Snellen methodology do not have lines that measure visual acuity between 20/100 and 20/200. Newer test charts, such as the Bailey-Lovie or the Early Treatment Diabetic Retinopathy Study (ETDRS), do have lines that measure visual acuity between 20/100 and 20/200.
Under the new criteria, if a person's visual acuity is measured with one of the newer charts, and they cannot read any of the letters on the 20/100 line, they will qualify as legally blind, based on a visual acuity of 20/200 or less. For example, if the person's best-corrected visual acuity for distance in the better eye was determined to be 20/160 using an ETDRS chart, they would now be classified as legally blind. Regardless of the type of test chart used, the person will not be classified as legally blind if they can read at least one letter on the 20/100 line. For example, if a person's best-corrected visual acuity for distance in the better eye was determined to be 20/125+1 using an ETDRS chart, they would not be classified as legally blind because they were able to read one letter on the 20/100 line.
To view the new rules please use the following link:http://www.ssa.gov/disability/professionals/bluebook/2.00-SpecialSensesandSpeech-Adult.htm