Natural history of quantitative autofluorescence in intermediate age-related macular degeneration

Purpose: To investigate differences in quantitative autofluorescence (qAF) imaging measurements between eyes with and without large drusen, and whether qAF measurements change over time in the eyes with large drusen. Methods: Eighty-five eyes from participants with bilateral large drusen and 51 eyes from healthy participants underwent qAF imaging at least once, and the age-related macular degeneration participants were reviewed 6-monthly. Normalized grey values at 9 degrees to 11 degrees eccentricity from the fovea were averaged to provide a summary measure of qAF values (termed qAF(8)). Results: In a multivariable model, qAF(8) measurements were not significantly different between age-related macular degeneration eyes with large drusen and healthy eyes (P = 0.130), and qAF(8) measurements showed a decline over time in the age-related macular degeneration eyes (P = 0.013). Conclusion: These findings add to the body of evidence that qAF levels are not increased in eyes with large drusen compared with healthy eyes, and qAF levels show a significant decline over time in the age-related macular degeneration eyes. These findings highlight how the relationship between qAF levels and retinal pigment epithelium health does not seem to be straightforward. Further investigation is required to better understand this relationship, especially if qAF levels are to be used as an outcome measure in intervention trials.