Discordance between Blue-Light Autofluorescence and Near-Infrared Autofluorescence in Age-Related Macular Degeneration

Abstract

Purpose : Blue-light autofluorescence (BL-AF; 488nm) and near-infrared autofluorescence (NI-AF; 787nm) visualize lipofuscin and melanin, respectively. We sought to evaluate the sources of discordance between these two imaging modalities in patients with age-related macular degeneration (AMD). We performed a prospective, observational clinical study to identify the lesions that result in discordance between BL-AF and NI-AF images and explore the structural correlates of these lesions using spectral-domain optical coherence tomography (SD-OCT).

Methods : A total of 86 eyes of 59 patients with a diagnosis of AMD were included. A masked observer examined the BL-AF, NI-AF and SD-OCT images. Areas with discordance of autofluorescence patterns between BL-AF and NI-AF images were correlated with structural findings at the corresponding location in SD-OCT scans.

Results : Seventy-nine eyes had discordance between BL-AF and NI-AF, of which thirteen eyes had greater than 50% discrepancy of the entire BL-AF and NI-AF abnormality. Pigment migration was the most common SD-OCT finding accounting for these discrepancies, with 37 lesions in 21 eyes. Subretinal hyper-reflective material (SHRM) had the greatest variability of appearance between BL-AF and NI-AF and was seen in 16 eyes. The most clinically significant finding was geographic atrophy missed on BL-AF in seven eyes.

Conclusions : Our findings indicate that variations in the distribution of lipofuscin, melanin and melanolipofuscin account for the majority of discordance between BL-AF and NI-AF. Evaluation of these discrepancies on SD-OCT demonstrated general groupings including pigment migration, calcific drusen, photoreceptor loss with intact RPE, SHRM and missed geographic atrophy. Given our findings of missed geographic atrophy lesions on BL-AF in 8% of eyes, clinicians should consider multimodality imaging, including NI-AF and OCT, especially in clinical trials of geographic atrophy.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

A: Left: GA isolated to the fovea, which normally appears as hypoBL-AF in healthy eyes. Middle: GA visualized as a hypoNI-AF area. Right: SD-OCT showing the presence of GA. B: Left: heterogeneous area of hypoBL-AF (bracket) and BL-AF without evidence of a lesion (arrow). Middle: homogenous area of hypoBL-AF indicating GA (bracket) with a hyperNI-AF lesion (arrow). Right: SD-OCT showing geographic atrophy (bracket) and a calcific drusen (arrow).