Correlation between retinal function and microstructural foveal changes in intermediate age related macular degeneration

Abstract

Purpose: To assess foveal microstructural changes influencing retinal sensitivity (RS) and fixation stability using microperimeter MP-1 in intermediate age-related macular degeneration (AMD). Methods: In this cross-sectional study, 22 eyes of 22 patients (mean age: 75 ± 9.02 years) with intermediate AMD were enrolled. Retinal sensitivity and bivariate contour ellipse area (BCEA) were obtained by microperimetry MP-1 (Humphrey 10-2 68-loci grid) under mesopic conditions. Drusen type, drusenoid pigment epithelial detachment, hyperreflective foci (HF), integrity of external limiting membrane (ELM), inner ellipsoid zone (ISel), RPE/Bruch's membrane complex (RPE/B) and subfoveal choroidal thickness were analyzed in the foveal region and compared with RS and BCEA. Spearman's rank correlation coefficient was used to evaluate the relationship between variables. Logistic regression analysis was also used to assess morphological predictor influencing RS or BCEA. Results: RS was strongly and inversely related with the presence of HF (r = -0.66, P = 0.001), integrity of ELM (r = -0.70, P < 0.001), ellipsoid zone (r = -0.45, P = 0.03). Instead, BCEA is positively related to the ellipsoid zone integrity (r = 0.45, P = 0.03). Logistic regression analysis confirmed that disruption of ISel influenced fixation stability (ExpB: 9.69, P = 0.04) but not RS. Instead, the presence of HF and disruption of ELM predicted RS reduction (ExpB: 0.55, P = 0.02 and ExpB: 0.29, P = 0.04, respectively). Conclusions: The integrity of ELM and the presence of HF are both predictors of RS. The ELM status may be considered a new biomarker of retinal function together with HF. Instead, the integrity of ISel band seems to be a more selective predictor of BCEA than RS.