Abstract
Purpose :
High 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™ metrics as clinical endpoints for future trials, we evaluated correlations between structural HMM™ metrics, spectral-domain OCT (SD-OCT, Heidelberg Engineering, Heidelberg, Germany) and retinal sensitivity on MAIA microperimetry (MP, CenterVue, Padova, Italy) in healthy subjects and p.arg142trp PRPH2-associated Central Areolar Choroidal Dystrophy (CACD) patients.
Methods :
We projected a default 10° MP grid on composite HMM™ images and performed automated cone density (CD), intercell distance (ICD) and nearest neighbor distance (NND) analysis at stimuli located at 3 and 5° retinal eccentricity. We averaged HMM™ metrics and MP sensitivity of each participant if located at similar eccentricity (3 or 5°) and meridian (superior, inferior, temporal or nasal) and calculated Pearson correlation coefficients. We manually measured outer retinal thickness (ORT) on SD-OCT in absolute scotomas and relative scotomas, outside of focal atrophy. We defined ORT as the distance between RPE/Bruch membrane and the external limiting membrane (ELM).
Results :
We included 15 genetically confirmed CACD patients and 5 healthy subjects. All correlations of HMM™ metrics and MP sensitivity at 3° reached statistical significance and are depicted in table 1. With exception of the inferior meridian with a Pearson r of -0,577 (p= 0,015396) for ICD, we were unable to find significant correlations at 5°. We found ORT in absolute scotomas to be statistically significant thinner (p=0.033) compared to relative scotomas of the same subject and retinal eccentricity, while CD of the corresponding areas did not differ significantly (p=0.945).
Conclusions :
We have established significant correlations between multiple structural metrics on HMM™ imaging and retinal sensitivity on MP in healthy subjects and p.arg142trp PRPH2-associated CACD patients. A multimodal approach combining SD-OCT with HMM™ imaging and MP may allow for detailed mapping of retinal photoreceptor integrity, which may be used as biomarkers in future clinical trials.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.