Assessing responses of the macula in patients with macular holes using a new system measuring localized visual acuity and the mfERG

Purpose: To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. Methods: We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We measured local visual acuity thresholds at 27 discrete locations within 21° diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function of visual field location, and local ERG responses within 45° diameter using the mfERG. Results: In the affected eyes, the mean FFIS visual acuity thresholds were significantly elevated within the central 21° diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8° in affected eyes. In the central 2°, 4 out of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. Conclusions: Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range).