Relationship between changes in foveal avascular zone area, metamorphopsia and aniseikonia in patients undergoing epiretinal membrane peeling

Abstract

Purpose : To evaluate relationships between changes in foveal avascular zone (FAZ) area, metamorphopsia, and aniseikonia pre- to post-epiretinal membrane (ERM) peeling surgery.

Methods : Pre- and post-op data were retrospectively reviewed in 13 adults (median 64y, range 50 to 74) undergoing ERM peel. FAZ areas (mm²) were obtained from automated output of OCT-A (Optovue), metamorphopsia measured using M-Charts, and aniseikonia with the Awaya New Aniseikonia Test, (horizontal and vertical values evaluated separately). Categorically, aniseikonia (pre- to post-op) was defined as increased (>2%), decreased (>2%), or no change (0±2%), from test-retest data. Pre- to post-op change in OCT-A FAZ was defined categorically as increased (>0.060 mm²), decreased (0.060 mm²), or no change (0±0.060 mm², from test-retest data. Relationships between change in metamorphopsia, change in aniseikonia and change in FAZ were evaluated by Spearman rank correlations. Agreement of pre- to post-op change category was compared between FAZ and aniseikonia using Bowker’s test and Kappa tests.

Results : From pre- to post-op, horizontal aniseikonia increased in 2 of 13 (15%), decreased in 5 (38%), and was unchanged in 6 (46%). For vertical aniseikonia, 3 (23%) increased, 6 (46%) decreased, and 4 (31%) were unchanged. For change in FAZ, 2 (15%) increased, 1 (8%) decreased, and 10 (77%) were unchanged. M-Chart changes ranged from –1.5 (improvement) to 0.2 (worsening) horizontally and –1.4 to 0.2 vertically. There was no correlation between pre- to post-op change in horizontal or vertical metamorphopsia and change in FAZ (r=0.1313, P=0.7 and r=0.3385, P=0.3 respectively) or between change in horizontal or vertical aniseikonia and change in FAZ (r=0.2691, P=0.5 and r=0.0549, P=0.9 respectively). There was no agreement between categories of either horizontal or vertical aniseikonia change and FAZ change (P=0.4 and 0.1 respectively, K= -0.23 and -0.03).

Conclusions : Following ERM surgery, some patients have increased FAZ area while others decrease. While remodeling of the photoreceptor mosaic is believed to occur after ERM peeling, there appears to be no relationship between pre- to post-op change in FAZ area and change in metamorphopsia or change in aniseikonia.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.