Abstract
Purpose :
Early age-related macular degeneration (AMD) has been associated with reduced retinal sensitivity (RS). This study assessed foveal microstructural changes influencing retinal sensitivity and fixation stability using microperimeter MP-1.
Methods :
In this cross-sectional study, 22 eyes of 22 patients (mean age: 75 ± 9.02 years) with intermediate AMD were enrolled. RS 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 (DPED), hyperreflective foci (HF), integrity of external limiting membrane (ELM), inner ellipsoid band (Isel), RPE/Bruch’s membrane complex (RPE/B) and subfoveal choroidal thickness (CT) were analyzed in the foveal region and compared with retinal sensitivity and fixation stability findings. Spearman’s rank correlation coefficient was used to evaluate the relationship between variables. Logistic regression analysis was also used to determine morphological predictor influencing RS or BCEA.
Results :
Mean RS was 12.67 ± 4.72 db, whereas mean BCEA was 1.94 ± 2.34 deg2. The RS was strongly and inversely related with the presence of HR (r=-0.66, P= 0.001), integrity of ELM (r=-0.70, P<.001), ellipsoid band (r=-0.45, P=.03). Instead, BCEA is positively related to the Isel integrity (r=0.45, P=.03). No relationships were found between drusen type and RS (P=.12) or BCEA (P=.45). Logistic regression analysis confirmed that disruption of ISel influenced fixation stability (ExpB: 9.69, P=.04) but not RS. Instead, the presence of HR and disruption of ELM predicted RS reduction (Exp B: 0.55, P=.02 and ExpB: 0.29, P=.04, respectively).
Conclusions :
RS is reduced in presence of HR, disruption of ELM and Isel bands, confirming its ability to show up early functional changes. Instead, BCEA increased in presence of Isel band disruption solely. In stages not involving photoreceptor band, RS is superior to BCEA in detecting functional dysfunction; unlike the RS, BCEA seems to be a selective biomarker of photoreceptor damage. Although these findings confirm that intermediate AMD can formerly cause visual dysfunction, they also provide additional morpho-functional insights that may be drive management and follow-up. Further studies will be needed to understand if functional damage may be an early biomarker of advanced AMD.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.