First Clinic Experiences of Transscleral Optical Imaging to Study Retinal Pigment Epithelium and Photoreceptor Cells

Abstract

Purpose : In vivo cellular imaging with transscleral optical imaging (TOI) (Cellularis^®, prototype Version 2.0) allows studying retinal structure and function. We currently conduct a prospective clinical validation study assessing retinal pigment epithelium (RPE) and photoreceptor (PR) cells with the TOI in subjects referred to the tertiary care eye clinic. Here we report on our observations of using this new technology.

Methods : Adult subjects (>18 years of age) with visual acuity <0.3logMAR and absence of pregnancy and epilepsy qualify for inclusion. Participants undergo full clinical examination including Optical Coherence Tomography (OCT) scanning followed by TOI imaging. If possible both eyes of a participant are imaged in 5 macular zones of 2mm x 2mm (Figure 1). Both RPE and PR layer images are acquired.

Results : By the end of 2021, we analyzed 206 eyes of 116 of participants (54% women; 46% men; mean age 59±18 years). RPE and PR images were acquired in at least 1 zone for all 206 eyes (Figure 2). For 75% (n=154) of the eyes, RPE and PR images were acquired in all 5 zones. Alignment and acquisition time was on average 1 minute per zone. When comparing the group of eyes where all 5 zones could be imaged to those where this was not the case, the proportion of participants with e.g. myopia ≤-2D or cataract was significantly higher (64% vs. 90%, p<0.001). However, especially with cataract, it depended on the type; image acquisition was easily feasible with myopic cataract for example. In subjects with darker colored eyes examination was easier than in those with light eyes (51% vs. 29%, p=0.008). Other factors, including insufficiently dilated pupils, higher degrees of astigmatism jeopardized complete image acquisition and quality. No adverse events were observed, only two subjects complained about slight discomfort during the examination.

Conclusions : Due to its good handling properties and quality of the presentation of RPE and PR cells, TOI has the potential to become a significant tool in the evaluation of retinal diseases.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Overview of image acquisition zones in RPE and PR modes respectively, superimposed to MultiColor fundus image.

 

Sample regions in RPE and PR mode of a green-eyed healthy subject (34y) with 0.38D Spherical Equivalent. RPE: the retinal pigment epithelial cells form a regular mosaic pattern. PR: each white dot represents an individual photoreceptor cell.