Full-field Electroretinogram in Extensive Macular Atrophy with Pseudodrusen-like deposits (EMAP)

Abstract

Purpose : To evaluate the extent of functional abnormalities in EMAP using full-field electroretinogram (ffERG).

Methods : Retrospective analysis of ffERGs from EMAP patients belonging to the large cohort of the rare disease center REFERET of 15-20 Hospital (Paris, France). The ffERGs were performed using a Diagnosys Espion system with the ColorDome LED full-field stimulator (Diagnosys LLC) following ISCEV standard protocols. We compared amplitudes and implicit time of the responses to an age-matched normative database using non-parametric “robust” Z-scores.

Results : The study included ERGs of 104 eyes from 52 patients with a median (IQR) age of 65.6 (63.4-68.5) years at the time of the examination. The majority of recordings showed amplitudes or implicit times outside the 95^th percentile of normative database: 76% (65/86) for DA 0.01 b-wave, 82% (72/88) for DA 3 b-wave, 86% (81/94) for DA 10 b-wave, 67% (64/96) for LA 3 b-wave, and 84% (81/96) for LA 30 Hz flicker (F1). Analysis of deviation from the median of the normative database confimed that DA recordings were more severely altered than LA ones. When comparing eyes with atrophy confined to the macula (early-stage EMAP) to those with atrophy extending beyond the temporal vascular arcades (late-stage EMAP), a similar pattern of alterations was observed, although the extent of deviation was less pronounced in the early-stage. The only exception was the LA 30Hz flicker implicit time, that was similarly pronged in both early- [median (IQR) of 4.5 (2.4-5.5) Z-scores] and late-stage EMAP [median (IQR) of 4.5 (3.5-5.5) Z-scores] (P = 0.46) (F2).

Conclusions : EMAP is characterized by a generalized retinal dysfunction affecting both rod and cone systems, even from its earliest stages. Our observations highlight the diagnostic and prognostic relevance of ffERG, especially for differentiating EMAP from other maculopathies with geographic atrophy.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

F1 – ERG waveforms amplitude and implicit times in EMAP. The green rectangles mark the normal limits (5^th and 95^th percentile) of amplitude and implicit time for each waveform. The dashed gray line represents a simulated control trace obtained by fitting the median a- and b-wave amplitude and implicit time (gray cross) from normative database.

 

F2 – Boxplots summarizing the distribution of ERG amplitude/implicit time deviation (Z-scores) from the median of healthy controls in the normative database (grey dashed line).