Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) in Eyes With Pigment Epithelial Detachments Due to Age-Related Macular Degeneration.

Purpose: To investigate fluorescence lifetime imaging ophthalmoscopy (FLIO) in neovascular AMD and pigment epithelial detachments (PEDs).

Methods: A total of 46 eyes with PEDs (>350 μm) as well as age-matched healthy controls were included in this study. We found 28 eyes showed neovascular AMD (nvAMD), and 17 had nonneovascular (dry) AMD (dAMD). The Heidelberg Engineering FLIO excited fluorescence at 473 nm. Fluorescence decays were detected in two spectral channels (498-560 nm; 560-720 nm) to determine fluorescence lifetimes of endogenous fluorophores in their specific spectral emission ranges. Mean fluorescence lifetimes (τm) were investigated. Multimodal imaging was reviewed by two ophthalmologists who circumscribed and classified PEDs as either serous (n = 4), hemorrhagic (n = 4), fibrovascular (n = 16), drusenoid (n = 17), or mixed (n = 5). Blood samples from a healthy subject and a patient with PED were investigated in a quartz cuvette.

Results: Eyes with nvAMD show similar FLIO patterns to dAMD: ring-shaped prolongations of τm 3 to 6 mm from the fovea. Different PED-forms show characteristic τm, while serous and hemorrhagic PEDs exhibit shortened τm, drusenoid PEDs show prolonged τm, and τm in fibrovascular PEDs is variable. Areas corresponding to sub-/intraretinal fluid display shortened τm. Ex vivo studies of blood also show short τm.

Conclusions: The previously described dAMD-related FLIO pattern is also present in nvAMD. Short τm in serous, fibrovascular, and hemorrhagic PEDs as well as sub/intraretinal fluid may disrupt this pattern. FLIO appears to differentiate between PEDs, hemorrhage, and fluid. Additionally, ex vivo studies of human blood help to better interpret FLIO images.