Lipofuscin- and melanin-related fundus autofluorescence in patients with ABCA4-associated retinal dystrophies.

Purpose: To compare melanin-related near-infrared fundus autofluorescence (NIA; excitation 787 nm, emission > 800 nm) to lipofuscin-related fundus autofluorescence (FAF; excitation 488 nm, emission > 500 nm) in patients with retinal dystrophies associated with ABCA4 gene mutations (ABCA4-RD).

Design: Observational case series.

Methods: Sixteen consecutive patients with ABCA4-RD diagnosed in one institution were included. FAF and NIA imaging were performed with a confocal scanning laser ophthalmoscope (Heidelberg Retina Angiograph 2; Heidelberg Engineering, Heidelberg, Germany). The pattern and size of retinal pigment epithelial (RPE) alterations detected with FAF and NIA were evaluated.

Results: FAF and NIA alterations were detected in all patients. In 7 of 16 patients, the alterations progressed beyond the vascular arcades, and in 9 of 16, they were confined to the macula. Spots of increased NIA (4/16) were less frequent compared with spots of increased FAF (15/16). Confluent patches of reduced NIA were frequent (12/16), and severely reduced NIA was observed in 3 cases. Areas with reduced NIA corresponded to either increased or reduced FAF. Preservation of subfoveal FAF or NIA corresponded to visual acuity > or = 0.4. Abnormalities detected with NIA were more extensive or more severe compared to FAF in 15 of 16 patients.

Conclusion: Patterns of FAF and NIA indicate different involvement of lipofuscin and melanin and their derivates in the pathophysiologic process of ABCA4-RD. NIA imaging provides a noninvasive in vivo visualization of RPE abnormalities that may precede FAF alterations during the degenerative process. Combined FAF and NIA imaging will provide further insight in the development of ABCA4-RD and could help to monitor future therapeutic interventions.