Comparison between multifocal electroretinography and microperimetry in age-related macular degeneration

Purpose: To correlate and compare retinal function measured using multifocal electroretinography (mfERG) with microperimetry in intermediate age-related macular degeneration (AMD).

Methods: Sixty AMD participants underwent multifocal electroretinography (mfERG) and microperimetry testing in one eye, and 44 control participants were included to provide normative values for each test. Thirteen hexagons in the central three rings of a 103-hexagon stimulus grid for mfERG and retinotopically matched points on microperimetry were chosen and converted into standard deviations (SDs) away from that of normal participants (Z-score) to represent the magnitude of measured functional deficit and to allow a comparison of the two measures.

Results: For the average of all points on mfERG and microperimetry, mfERG N1 to P1 response amplitude and microperimetric retinal sensitivity was significantly lower (P = 0.013 and P < 0.001, respectively) and mfERG P1 implicit time was significantly increased (P < 0.001) in the AMD participants compared to those in the control participants. Considering retinotopically matched points, there was no significant correlation between the average Z-scores of the microperimetric retinal sensitivity and mfERG implicit time (correlation coefficient, R = 0.254, P = 0.051), nor response amplitudes (R = 0.006, P = 0.965), and the measured functional deficit with microperimetry was consistently greater than both mfERG parameters (P < 0.001).

Conclusions: The measured functional deficit with microperimetry was greater than mfERG parameters in eyes with intermediate AMD. The absence of correlations between these two measures suggests that mfERG may be capturing unique aspects of retinal dysfunction. These findings are important when considering the use of these functional measures in intermediate AMD.