Legal or Statutory Blindness
Legal or statutory blindness is a term used by the Social Security Administration for a disability standard of vision loss. Rules regarding the measuring of visual acuity and visual field loss were updated in 2007.
Statutory/legal blindness is defined as one of the following:
1. Best corrected visual acuity of 20/200 or less in the better eye;
2. Visual field limitation such that the widest diameter of the visual field, in the better eye, subtends an angle no greater than 20 degrees.
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 updates to the law in 2007, if a person's visual acuity is measured with one of the newer charts like the Bailey-Lovie or the Early Treatment Diabetic Retinopathy Study (ETDRS), and they cannot read any of the letters on the 20/100 line, they will be considered as legally blind. This change was made because the original acuity requirement was based on Snellen projection acuity which did not have any acuity measurements between 20/100 to 20/200.
So for example, if the person's best-corrected visual acuity for distance in the better eye was determined to be 20/160 using the Bailey-Lovie or ETDRS chart, they would now be classified as legally blind. A person will not be classified as legally blind if they can read even one letter on the 20/100 line.