Microperimetry fixation characteristics in an Amish Population with Age-Related Macular Degeneration

Abstract

Purpose : To evaluate the fixation characteristics in mesopic and scotopic conditions using microperimetry in an elderly Amish population with age-related macular degeneration (AMD).

Methods : Mesopic and scotopic microperimetry (MP-1S; Nidek Technologies) exams were performed on 86 elderly (age >50) Amish subjects from Pennsylvania. Fixation stability (stable, relatively unstable, and unstable), fixation location (predominantly central, predominantly eccentric and poor central), and fixation percentage within 2° and 4° diameter circle were measured. In addition, all subjects underwent color fundus photography and certified Ocular Disease Evaluators (ODEs) at the Doheny Image Reading Center identified subjects with evidence of AMD as defined by the Beckman classification. Fixation characteristics were compared between mesopic and scotopic MP exams in eyes with AMD, and between AMD eyes and age matched controls.

Results : 142 eyes of 86 subjects were evaluated; 87 eyes were normal and 55 eyes had evidence of early or intermediate AMD. For mesopic MP1 testing (Table), neither fixation location nor stability were significantly influenced by the presence of AMD (p=0.36 and p=0.68, respectively). For scotopic MP1 testing, the presence of AMD did not significantly influence the stability of fixation (p=0.06), but the location of fixation was more frequently eccentric (p=0.02). The fixation percentage within the 2° circle was not influenced by the presence of AMD in either mesopic or scotopic conditions (p=0.11 and p=0.07 respectively). Within the 4° circle, however, presence of AMD impacted the fixation percentage under scotopic conditions (p=0.04), but not mesopic conditions (p=0.86).

Conclusions : The presence of early/intermediate AMD does not appear to influence fixation (location or stability) under mesopic conditions, but does appear to shift fixation more eccentrically under scotopic conditions. The relevance of scotopic fixation testing in AMD warrants further study.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Table 1. Stability, Location, and Percent of fixation in Amish subjects with AMD and age matched normal. P-values for stability, site, and fixation for both AMD subjects and normal were analyzed using Fisher’s exact test.