Multifocal Electroretinograms in Amblyopic Patients

ABSTRACT

PURPOSE: To evaluate the results of amblyopia on multifocal electroretinogram (mfERG). METHODS: The mfERG procedure was performed on nineteen monocular amblyopic patients (age ranged from 7 to 42 years) using the VERIS(TM) (EDI, San Mateo, CA) system. The central 30 degrees of ocular fundus were stimulated by an array of 103 hexagonal elements for four minutes. The responses of six concentric rings (rings 1 to 6) radiating from the foveal center were averaged, and the latencies and amplitudes of N1, P1 and N2 were compared with the findings of the normal contralateral eyes. The mfERG procedure was recorded again after improvement of vision in one patient (No. 4) who underwent occlusion treatment for one month. RESULTS: There were no significant differences of N1, P1 and N2 latencies between normal contralateral and amblyopic eyes (P>0.05). However, P1 amplitudes of the amblyopic eyes were reduced significantly compared with those of the normal contralateral eyes on rings 1 and 2 (P<0.05). N1 and N2 amplitudes of the amblyopic eyes were also reduced, but not significantly. After the successful occlusion treatment of patient No. 4, the responses of the amblyopic eye were improved but not the level of the contralateral normal eye. CONCLUSIONS: These results suggest that amblyopia may cause some changes in mfERG responses, especially in terms of amplitudes of the central retina. Further investigation is needed to determine whether these results are due to the physiologic change(s) of the amblyopia itself or to fixation instability during the test.