Transscleral optical phase imaging revealing the choriocapillaris structure

Abstract

Purpose : Transscleral optical phase imaging (TOPI) has been developed in order to visualize retinal pigment epithelium (RPE) cells in vivo. In addition, it reveals a background reflectance pattern which is investigated in this study as the choriocapillaris structure.

Methods : Healthy volunteers and participants with non-neovascular AMD were recruited for TOPI, associated with conventional imaging: spectral domain optical coherence tomography, autofluorescence, color and infrared fundus imaging. Six squares of 5.04x5.04 degrees were acquired with TOPI: one was foveal, four were localized in the macular quadrants with 3.8° eccentricity, and one to the investigators discretion. The resulting TOPI images were confronted with information from conventional multimodal imaging. The results are presented in a descriptive way.

Results : Included were 51 healthy eyes from 30 volunteers (mean age 35±11 years; 37% females), and 10 eyes of 8 AMD patients (mean age 75.5±5.5 years, 50% females). The RPE cells visualized in healthy participants showed a hexagonal pattern with a darker center and a lighter border. However, this pattern was seen on reticular pattern of linear zones with lighter and darker background grey, of 2 to 3 RPE cells width. This reticular background pattern was highly regular in healthy eyes. In AMD eyes with atrophic changes it became a dominant image feature due to high contrast, showing more irregularity. However, in deeper atrophy, the reticular pattern was lost and only larger choroidal vessels were visible. All observations suggested that the reticular pattern corresponds to the choriocapillaris.

Conclusions : TOPI reveals, in vivo, the human choriocapillaris structure in addition to the RPE cells. This novel imaging capacity may be of great value in order to study various pathologies involving the choriocapillaris.

This is a 2021 ARVO Annual Meeting abstract.

 

TOPI from a healthy volunteer – reticular black-white background pattern, revealing the choriocapillaris reflectance behind the RPE cells. In zones of extreme reflectance or absorption, the RPE cells may not be visible.

 

TOPI from an AMD patient with atrophy – the reticular choriocapillaris pattern becomes highly contrasted and slightly irregular in the atrophic area