Abstract
Purpose :
Late-onset retinal degeneration (L-ORD) is an autosomal dominant macular dystrophy with anterior segment involvement, notably long anterior zonules (LAZs). In this study, we aim to analyze LAZs in a cohort of L-ORD patients.
Methods :
This prospective, single-center study included patients with a genetic diagnosis of L-ORD from 2011-2016. Imaging included true-color non-mydriatic anterior segment photographs by slit-lamp retroillumination. LAZs were identified, marked and plotted using Matlab (R2021a) (Figure 1). The zonule-free zone (ZFZ) was calculated using the longest LAZ to the pupillary axis scaled to an average pupil size of 12 mm. The LAZs number and location, ZFZ length, iris transillumination defects, pachymetry, and features on gonioscopy were described. Calculations were performed on SPSS (v. 25; IBM) with p<0.05.
Results :
Twelve eyes from 6 patients (median age = 60.5 years, range 56-70; 4 males) were included (Figure 2); one case (2 eyes) was excluded due to inadequate imaging. LAZ length measurement showed high inter-rater (ICC=0.98; p< 0.001) and test-retest repeatability (ICC=0.97; p<0.001). There was marked variability in the number of LAZs in the cohort, with a median of 160 (range: 11-372). LAZ prevalence varied with quadrant: superior (39%), inferior (24%), nasal (19%), and temporal (18%). LAZ was strongly correlated between right and left eye (r=0.98, p=0.001), with no significant difference between eyes (p=0.34). Additionally, LAZ was strongly correlated with pachymetry (r=0.92; p=0.01) and inversely with age (r=-0.78; p<0.05). Scaled ZFZ had a median of 2.0mm (range:1.3-5.4), without significant differences in size between eyes of patients (p=0.34). ZFZ was correlated with age (r=0.85; p=0.03) but not with total LAZ number (r=-0.68; p=0.14).
Conclusions :
This study validates a method for measuring and counting LAZ in L-ORD. In our cohort LAZs are most prevalent in the superior quadrant. LAZ number and ZFZ were symmetrical between L-ORD eyes. ZFZ is smaller in L-ORD patients compared to previous studies of LAZ. The reduced LAZ count in older patients and increased ZFZ may suggest a decrease in the number of zonules with time with a primary loss of longer LAZ. The LAZ findings require validation in a larger cohort, planned as part of an ongoing longitudinal study.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.