Macular subfield thickness measurements in Alport syndrome

Abstract

Purpose : Temporal macular thinning has been shown in patients with Alport syndrome (AS), particularly in X-linked males (XLM). We investigated macular retinal thickness measurements in a cohort of AS patients (including females with X-linked disease (XLF) and patients with autosomal recessive (AR) disease), making comparisons with matched control subjects and exploring association with visual acuity (VA).

Methods : Patients underwent macular optical coherence (OCT) imaging (3D OCT-1000, Topcon Corporation, Japan). One eye was included per subject. Data collected included age, genotype, VA, average retinal thickness (AvRT) and ETDRS 9-subfield thickness (outer (O), inner (I); superior (S), inferior (I), nasal (N) temporal (T) and central (C)). Temporal thinning index (TTI) was calculated using the formula ((ON+IN)-(OT+IT))/(IN+ON) x100. Data were compared using Mann-Whitney-U tests and associations measured with robust logistic or linear regression models. OCT measurements were compared with similar data from 30 age and sex-matched control participants.

Results : 30 patients (15 XLM, 10 XLF, 5 AR genotypes) were included. Comparison with controls revealed a significant difference for TTI, AvRT and all EDTRS subfields (all p≤0.01), except for the IN region (p=0.162). On subgroup analysis, only OT and OS subfield thickness remained significantly different from controls in each AS subgroup (all p<0.05), while TTI only remained significantly different in XLM (p≤0.001). XLM subjects had significantly greater TTI than XLF subjects (p<0.001). Age-adjusted logistic regression demonstrated significant association between AvRT, OT and OS with each AS subgroup (all p<0.05), and TTI with XLM phenotype (OR: 3.85 [95%CI: 1.68-8.84], pseudo-R² 0.79, p=0.001). OT thickness was most strongly predictive of XLF or AR genotypes (AUC 0.89), while TTI was most strongly predictive of XLM genotype (AUC 0.99). In the XLM group, age-adjusted VA was significantly associated with all retinal thickness measurements (all p≤0.02), except the ON subfield (p=0.078).

Conclusions : Alport syndrome is associated with generalized macular thinning, which is detectable in all EDTRS subfields, with the exception of the IN region. We found that retinal thickness metrics varied by subgroup, but numbers were small. In addition, most OCT thickness metrics demonstrated correlation with VA in the XLM subgroup.

This is a 2021 ARVO Annual Meeting abstract.

 

Retinal features of Alport syndrome

 

Comparison of macular thickness measurements