Fundus autofluorescence and photoreceptor cell rosettes in mouse models

Area of Science:

• Ophthalmology
• Retinal Imaging
• Molecular Biology

Background:

• Fundus autofluorescence (AF) is a non-invasive imaging technique.
• Lipofuscin accumulation in the retinal pigment epithelium (RPE) is associated with retinal diseases.
• Understanding the structural basis of AF is crucial for diagnosing and monitoring retinal conditions.

Purpose of the Study:

• To investigate correlations between fundus AF, RPE lipofuscin accumulation, and photoreceptor cell degeneration.
• To determine the structural basis of hyperautofluorescent spots observed in fundus AF images.

Main Methods:

• Fundus AF imaging and spectral-domain optical coherence tomography (SD-OCT) were performed on Rdh8(-/-)/Abca4(-/-) mice.
• Quantitative AF (qAF) and retinal bisretinoid levels (A2E) were measured.
• Histometric analysis of outer nuclear layer (ONL) thickness and fluorescence microscopy were utilized.

Main Results:

• qAF intensity and A2E levels increased up to 4 months, after which A2E declined while qAF continued to rise.
• Decreased A2E levels correlated with reduced photoreceptor viability (ONL thinning).
• Hyperautofluorescent puncta in AF images corresponded to photoreceptor cell rosettes seen in SD-OCT and histology.

Conclusions:

• Disordered neural retina can contribute AF to fundus images.
• Hyperautofluorescent puncta in fundus AF images can be attributed to photoreceptor cell rosettes.