Visible light OCT-based quantitative imaging of lipofuscin in the retinal pigment epithelium with standard reference targets.

Zahra Nafar,Shuliang Jiao,Rong Wen

doi:10.1364/boe.9.003768

Abstract

We developed a technology for quantitative retinal autofluorescence (AF, or FAF for fundus AF) imaging for quantifying lipofuscin in the retinal pigment epithelium (RPE). The technology is based on simultaneous visible light optical coherence tomography (VIS-OCT) and AF imaging of the retina and a pair of reference standard targets at the intermediate retinal imaging plane with known reflectivity for the OCT and fluorescence efficiency for the FAF. The technology is able to eliminate the pre-RPE attenuation in FAF imaging by using the simultaneously acquired VIS-OCT image. With the OCT and fluorescence images of the reference targets, the effects of illumination power and detector sensitivity can be eliminated.

Highlights

Lipofuscin, a complex mixture of partially digested lipids and protein components in the retinal pigment epithelium (RPE) cells, is a major source of fundus autofluorescence (FAF) [1, 2]
The logarithm of the fluorescent signals from the master reference in the model eye linearly decreases with the OD values of the neutral density (ND) filters at a slope of −2, which agrees with the round-trip attenuation of light through the ND filter and the listed transmission data of the ND filters
Since melanin is distributed at a higher concentration in the apical portion of RPE cells, and lipofuscin is more concentrated in the basal portion [27], melanin could significantly attenuate the AF signals. These results suggest that the qAF/qOCT ratio is independent of melanin in the RPE, and the system is capable to compensate signal attenuation by RPE melanin

Summary

Introduction

Lipofuscin, a complex mixture of partially digested lipids and protein components in the retinal pigment epithelium (RPE) cells, is a major source of fundus autofluorescence (FAF) [1, 2]. It accumulates with age and is implicated in age-related macular degeneration (AMD) and Stargardt disease [3]. It is difficult to compare images obtained by the currently available technologies from the same person over time, or from different individuals, which hinders the clinical usefulness of FAF images [17, 18]. It is a challenge to obtain the absolute intensity of FAF

Methods

Results

Discussion

Conclusion