Evaluation of patients with visual field defects following macular hole surgery using multifocal electroretinography

Purpose: To investigate patients with visual field defects following macula r hole surgery to determine the cause of such defects, specifically with re ference to ischemic damage versus mechanical trauma. Methods: Five patients with known visual field defects following macular ho le surgery were studied with Goldmann perimetry, Humphrey automated perimet ry, and multifocal electroretinography (MERG). Three patients returned at a later date for nerve fiber layer analysis. Results: None of the five patients demonstrated evidence of a- or b-wave lo ss on MERG in the regions corresponding to the visual field defects. Two of three patients studied with the nerve fiber layer analyzer demonstrated si gnificant loss of nerve fiber layer thickness in the quadrant corresponding to the field defect. Conclusion: The normal MERG results indicate that the possibility of an art eriolar occlusion as the principal cause for the defects is unlikely in mos t cases. Data suggest that the site of damage is in the nerve fiber layer, although the specific cause of this damage remains to be determined.