| legal blindness | Generally, visual acuity of less than 6/60 or 20/200 using Snellen test types, or visual field restriction to 20 |
|---|---|
| functional blindness | Apparent loss of vision related to suggestibility. (05 Mar 2000) |
| letter blindness | Visual agnosia for letters. The subject sees the letters but cannot identify them; caused by a lesion in the occipital cortex. (05 Mar 2000) |