The value of multifocal electroretinography to predict progressive visual acuity loss in early AMD

BACKGROUND: To investigate, in a prospective study, the role of multifocal electroretinography (mfERG) for predicting visual acuity decline in early age-related macular degeneration (AMD) with time. METHODS: Twenty-six early AMD patients (12 males and 14 females, mean age 66.9 ± 9.8; range 46-82 years) were included in the study. A complete ophthalmic examination and mfERG (Retiscan, Roland Germany, ISCEV standard protocol) were performed at the study entry (baseline), after 20 and 24 months. The first-order kernel mfERG responses were analyzed by ring analysis. The amplitude density (AD) of the first positive peak (P1, nV/deg(2)), the P1 amplitude (µV) and P1 implicit time (ms) for Rings 1 (central) to 6 (most peripheral) were evaluated. Data were statistically analyzed by analysis of variance and receiver operating characteristic (ROC) curves. RESULTS: The loss in the mfERG Ring 1 AD from normal control values, recorded at baseline, was correlated with the decrease in ETDRS visual acuity with time (P = 0.004). ROC analysis showed that, after 24 months, the average decline in visual acuity was greater (3 letters vs 0.4 letters, P = 0.0021) in patients whose Ring 1 P1 AD at baseline was equal to or less than 65.9 nV/deg(2), compared to those with higher AD values. Both P1 amplitude and AD of Ring 1 had an area under the curve of 0.702 (95% confidence interval 0.50-0.92) with a sensitivity of 64.3% (35.14-87.24%) and a specificity of 91.7% (61.52-99.79%). CONCLUSIONS: The present results indicate that mfERG P1 amplitude and AD of Ring 1 may be highly specific to predict visual acuity decline in early AMD.