In vivo lipofuscin quantification by visible-light optical coherence tomography-based fundus autofluorescence imaging

Area of Science:

• Ophthalmology
• Biomedical Imaging
• Retinal Research

Background:

• Fundus autofluorescence (FAF) provides insights into retinal health.
• Quantifying lipofuscin in the retinal pigment epithelium (RPE) is crucial for understanding age-related macular degeneration and other retinal diseases.
• Previous methods lacked precise in vivo quantification of RPE lipofuscin.

Purpose of the Study:

• To develop and validate a novel imaging technique for simultaneous FAF and OCT.
• To establish a quantitative measure of RPE lipofuscin concentration in vivo.
• To demonstrate the clinical potential of this technique for retinal disease assessment.

Main Methods:

• Development of visible-light optical coherence tomography-based fundus autofluorescence (VIS-OCT-FAF) for simultaneous FAF and OCT imaging.
• Quantification of FAF and OCT signals from the RPE (qAF/qOCT ratio).
• Correlation of qAF/qOCT with ex vivo A2E measurements and in vivo lipofuscin concentration using a fluorescence calibration curve.

Main Results:

• The qAF/qOCT ratio was confirmed as a true representation of total RPE fluorophores, linearly correlating with lipofuscin concentration.
• An intensity equivalence (INEQ) was established between RPE fluorophores and A2E concentration.
• VIS-OCT-FAF revealed higher lipofuscin content in pigmented rats compared to albinos, highlighting the need for quantified FAF intensity.

Conclusions:

• VIS-OCT-FAF enables accurate, quantitative in vivo assessment of RPE lipofuscin.
• This technology expands the clinical applications of FAF imaging.
• The findings pave the way for improved diagnosis and monitoring of retinal diseases related to lipofuscin accumulation.