Visual evoked responses in the assessment of field defects in glaucoma.

A technique for producing steady state visual evoked responses (VERs) to pattern reversal stimulation of retinal areas corresponding to discrete field quadrants is described. Patients examined included 10 normal individuals, 11 patients with ocular hypertension, and 21 with glaucomatous field defects (unilateral except in two cases with bilateral defects). The VERs relating to normal homonymous field quadrants were in phase in all three groups, excluding patients with cataracts. The VERs corresponding to quadrants with small field defects showed a phase shift compared with responses from normal homonymous quadrants in all cases, but were not detectable if the defect filled more than three quarters of the quadrant tested in most cases. The method offers a means for the objective assessment of visual fields in patients with unilateral optic nerve lesions, provided that central visual acuity is 20/80 or better