Chromaticity analysis comparing a white light confocal imaging device versus a flash fundus camera

Abstract

Purpose : To evaluate the chromaticity of color fundus photographs acquired with a white light confocal camera compared to a conventional non-mydriatic fundus camera.

Methods : A fully automated retinal imaging system (Eidon, Centervue, Padova, Italy) was used to capture fundus images from healthy volunteers and patients with retinal diseases. Images were compared to a non-mydriatic color fundus camera (Triton, Topcon Corporation, Tokyo, Japan). All color images were evaluated with respect to the chromaticity. Color analysis was performed according to the image color signature. Color signature of an image was defined as the distribution in the RGB space of the normalized chromaticity of its pixels. The set of descriptors for assessing chromaticity was represented as the average of the standard deviations of the normalized chromaticity for each color axis, the standard deviation of the distribution of the barycenter positions on different eyes and the normalized chromaticity value.

Results : Fifty central field color fundus photographs were acquired with each retina camera. Imaging was performed on 5 healthy volunteers, 10 subjects with diabetic retinopathy, 15 eyes affected by age-related macular degeneration, 10 cases with retinal vascular occlusion and 10 eyes affected by retinal dystrophies. The average of the standard deviations of the normalized chromaticity were, respectively, 0.038, 0.026 and 0.032 for axes R,G and B with the confocal white-light device, and 0.035, 0.020 and 0.021 for axes R,G and B using the non-mydriatic flash camera. The standard deviation of the distribution of the barycenter positions on different eyes was 0.051, 0.022 and 0.060 for axes R,G and B using the confocal white-light imaging system and 0.030, 0.016 and 0.019 for channels R,G and B using the flash fundus camera. The unique normalized chromaticity value was 0.085% for Eidon and 0.028% for Topcon camera.

Conclusions : Confocal white-light Eidon imaging produces images with a higher variety of pixels in the color image, and a wider richness of color content. The overall higher chromaticity of the Eidon may provide benefits in terms of fidelity to real retinal appearance. Further validation in larger masked studies is needed.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.