Author: Leila Sara Eppenberger
Co-authors: Safa Mohanna, Michael A. Thiel, Martin K. Schmid
Abstract
PurposeTransscleral optical imaging (TOI) is a novel microscopy technique which allows in vivo cellular imaging and studying retinal morphology and function. We report our first general experiences using this new technology in healthy controls and move forward to an exploration of the potential of this technique. The main focus of this particular showcase is the presentation of “3G” (i.e. “G” as in grades) images of the three superimposed retinal layers: Retinal pigment epithelium (RPE), photoreceptor (PR) cells and nerve fiber (NF) layer.
Setting/Venue
The principal trial is a single center prospective study conducted at a tertiary care eye clinic. The protocol is registered on ClinicalTrials.gov (identifier: NCT04912622). All participants signed the study specific informed consent.
Methods
Adults (>18 years of age) with visual acuity <0.3logMAR and absence of pregnancy and epilepsy qualify for inclusion to the main study. Participants undergo full clinical examination, followed by optical coherence tomography (OCT) scanning and optical biometry examinations, before TOI is conducted with the novel retinal camera Cellularis® (prototype version 2.0). If possible both eyes of a participant are imaged in five macular zones of 2mm x 2mm. RPE and PR layer images are acquired consistently, and in some selected cases additional NF images are acquired. The decisive factor for performing the third layer NF images, is the presence of high-quality images of RPE and PR layers. Here a specific selection of images acquired within the main study is presented.
Results
By the end of 2021, we analyzed 206 eyes of 116 healthy participants (54% women; mean age 59±18 years). RPE and PR images were acquired in at least 1 zone for all 206 eyes. For 75% (n=154) of the eyes, RPE and PR images were acquired in all 5 zones. In a total of 32 eyes (16%) belonging to 20 subjects (17%) NF images for at least one of the five macular zones was acquired. Images of the retinal “3G”, i.e. RPE, PR and NF layers could be selected and showcased: RPE cells appear with a regular mosaic pattern, PR cells emerge as white dots, like “stars on a dark night sky”, and finally the NF layer becomes visible as fine regular bundled lines.
Conclusions
A selection of images of the retinal “3G” - RPE, PR and NF, is presented to highlight TOI’s potential to comprehensively capture retinal architecture in vivo on a cellular level, thus possibly contribute to a better understanding of a wide range of retinal diseases in the near future.
