Reduced amplitude and delayed latency in foveal response of multifocal electroretinogram in early age related macular degeneration

Aim-To explore the use of multifocal electroretinograms (MERG) in detecting early changes in age related macular degeneration (AMD). Method-15 pre-AMD or early AMD eyes showing retinal drusen or irregular fun dus pigmentation with window defects by fluorescein angiography (FA) and mi ldly decreased visual acuity were examined and compared with their asymptom atic fellow eyes. 20 age matched normal eyes were included as controls. MER G was recorded by a Veris system (version 3.0) using a 103 hexagon stimulus and 218 second total recording time per eye. The first order kernel was us ed to calculate amplitudes and latencies in three configurations: the nasal and the temporal areas, the superior and the inferior areas, and six conce ntric rings centred on the fovea. Results-There were no significant differences in the amplitudes and the lat encies between the different regions (nasal versus temporal and superior ve rsus inferior) of the retina as well as between the different groups of eye s (normal, pre-AMD or early AMD, and the asymptomatic fellow eyes) in each region. Using the concentric configuration, the foveal amplitude of pre-AMD or early AMD eyes was significantly suppressed when compared with the age matched control group and their average latency was longer in the fovea tha n in outer rings and significantly prolonged when compared with the normal control group. Similar changes in amplitude and latency were also observed in the asymptomatic fellow eyes. Conclusion-Significant abnormality in the foveal amplitude and the foveal l atency of MERG could be detected in pre-AMD or early AMD eyes as well as th eir asymptomatic contralateral eyes, suggesting MERG as a sensitive tool in detecting early foveal abnormalities in AMD.