# Clinical and Molecular Characteristics of Foveal Sparing Phenotype in Chinese Patients With Inherited Retinal Diseases

## TL;DR

This study examines the foveal sparing phenotype in Chinese patients with inherited retinal diseases, finding it is linked to better vision and more common in certain genetic types.

## Contribution

The study identifies the foveal sparing phenotype's association with specific IRD genes and introduces residual ellipsoid zone area as a predictive biomarker.

## Key findings

- Foveal sparing is more common in EYS and USH2A-related retinopathy.
- Residual ellipsoid zone area on OCT correlates with visual acuity and predicts vision deterioration.
- The foveal sparing phenotype is linked to better visual prognosis in IRD patients.

## Abstract

The purpose of this study was to evaluate the clinical characteristics of the foveal sparing phenotype among patients with inherited retinal diseases (IRDs) and to identify the predictive imaging markers for visual prognosis.

Consecutive patients with definitive clinical and genetic diagnoses of IRD who first visited our clinic from November 2021 to December 2022 and had high-quality spectral-domain optical coherence tomography (SD-OCT) images were included in this retrospective cohort. The foveal sparing phenotype was defined by foveal preservation on autofluorescence (FAF) and OCT images. Best-corrected visual acuity (BCVA) and dimensions of residual structures of outer retinal layers on OCT and FAF images were measured and analyzed. Spearman correlation analysis was performed to evaluate the correlation between retinal imaging features and BCVA. Receiver operating characteristic (ROC) curve was performed to assess the predictive performance of residual ellipsoid zone (EZ) area on OCT.

A total of 601 eyes of 308 Chinese patients with IRD were enrolled. Foveal sparing phenotype was observed in 195 (32.4%) eyes of 105 (34.1%) patients. There were 46.7% of cases with USH2A-related retinopathy and 76.9% EYS-related retinopathy presented foveal sparing phenotype, whereas their structural integrity showed no significant difference. Spearman correlation analyses revealed significant association between residual EZ area (P < 0.01) and BCVA. ROC curve analysis demonstrated that the residual EZ area at initial diagnosis could predict the degree of BCVA deterioration within 2 years (area under the curve [AUC] = 0.70).

Our findings indicate that the foveal sparing phenotype is associated with better visual prognosis and is more frequently observed in IRDs associated with EYS and USH2A mutations. The residual EZ area on OCT can serve as a predictor of the timeframe for central vision deterioration to blindness in patients with IRD.

Residual EZ area on OCT can serve as a predictive biomarker to support clinical decision making in monitoring and managing the progression of IRD.