Structure–function correlation of retinal photoreceptors in PRPH2‐associated central areolar choroidal dystrophy patients assessed by high‐resolution scanning laser imaging and microperimetry

Abstract

AbstractPurposeHigh Magnification Module (HMM™, Heidelberg Engineering, Heidelberg, Germany) imaging is a novel technique, designed to visualize the retina at a cellular level. To assess the potential of HMM™‐based metrics as endpoints for future trials, we evaluated correlations between structural HMM™ cone metrics, spectral‐domain OCT (SD‐OCT, Heidelberg Engineering, Heidelberg, Germany) and retinal sensitivity on microperimetry (MP, MAIA, CenterVue, Padova, Italy) in healthy subjects and p.(Arg142Trp) PRPH2‐associated Central Areolar Choroidal Dystrophy (CACD) patients.MethodsWe projected a default 10° MP grid on composite HMM™ images and performed automated cone density (CD), intercell distance (ICD) and nearest neighbour distance (NND) analysis at stimuli located at 3° and 5° retinal eccentricity. We manually measured intrasubject outer retinal thickness on SD‐OCT in absolute and relative scotomas, located outside of focal atrophy.ResultsWe included 15 CACD patients and five healthy subjects. We found moderate‐to‐strong correlations of HMM™ metrics and MP sensitivity at 3° eccentricity from the fovea. We found the outer retina at the locations of absolute scotomas to be statistically significant thinner (p = 0.000003, one‐sample t‐test), as the outer retinal thickness at locations of relative scotomas. Interestingly, HMM™ metrics of these areas did not differ significantly.ConclusionsWe found significant correlations between structural photoreceptors metrics on HMM™ imaging and retinal sensitivity on MP in healthy subjects and CACD patients. A multimodal approach, combining SD‐OCT, MP and HMM™ imaging, allows for detailed mapping of retinal photoreceptor integrity and restitution potential, important data that could serve as biomarkers in future clinical trials.