Dethecting glaucomatous damage with the Friedmann analyzer compared with te Goldmann perimeter and evaluation of stereoscopic photographs of the optic disk.

We used a Friedmann visual field analyzer with a 98-hole plate to test 32 normal control eyes and to establish highly specific criteria for abnormality. When these criteria were later applied to the testing of 50 additional normal control eyes, there were no false-positive abnormalities. With these criteria, the Friedmann visual field analyzer proved to be at least as sensitive as careful manual perimetry with the Goldmann perimeter in detecting early glaucomatous visual field defects. In addition to having high sensitivity and specificity, the Friedmann visual field analyzer with the 98-hole plate is rapid and requires very little training to operate. By way of comparison, examination of stereoscopic photographs of the optic disk was also sensitive in detecting or suggesting glaucomatous damage with visual field loss, but some of the normal control optic nerves were also considered suspect. Ignoring the suspect disks in order to reduce false-positive results improved specificity but simultaneously reduced sensitivity for detecting definite visual field loss. The combination of optic disk evaluation and visual field testing (with wither the Goldmann or the Friedman instrument) better detected early cases than did either test alone, because each method picked up some early cases missed by the other.