Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) in Patients with Choroideremia

Abstract

Purpose : Choroideremia (CHM) is a rare progressive retinal dystrophy that causes night blindness, peripheral vision loss, and diminished central vision later in life as peripheral atrophy progresses. This study investigates fluorescence lifetime patterns in patients diagnosed with CHM utilizing fluorescence lifetime imaging ophthalmoscopy (FLIO).

Methods : 30 eyes of 15 subjects with CHM (mean age 28 ± 14 years) as well as 15 age-matched healthy subjects were investigated in this study. Mutations to the CHM gene were confirmed with genetic testing. FLIO images of a 30° retinal field centered at the fovea were acquired at the Moran Eye Center in Salt Lake City, Utah using a prototype Heidelberg Engineering Spectralis-based FLIO. FLIO lifetimes were recorded in short (498-560 nm, SSC) and long (560-720 nm, LSC) spectral channels and mean autofluorescence lifetimes (t_m) were calculated. Optical coherence tomography (OCT) scans were recorded for each patient.

Results : Patients with CHM exhibit specific FLIO lifetime patterns. Most CHM patients showed consistently prolonged lifetimes in the peripheral retina corresponding to hypofluorescent areas in autofluorescence intensity images and retinal atrophy. In the central macula, t_m was unrelated to the autofluorescence intensity. Some areas of persistent pigment epithelial islands showed prolonged FLIO lifetimes, whereas other areas of hypofluorescence showed short FLIO lifetimes. Two patients were reexamined a year after their initial visit, these patients showed prolonged lifetimes in areas of hypofluorescence at follow-up, but not in unaffected areas.

Conclusions : FLIO shows distinct patterns in patients with CHM, which differ from conventional autofluorescence images. FLIO may show regions of altered signal in areas that in autofluorescence imaging present as unremarkable. Furthermore, some hypofluorescent areas show normal FLIO lifetimes, suggesting preservation of functional retinal tissue. FLIO can be used to gain more differentiated knowledge about pathophysiology and atrophy progression in CHM compared to conventional imaging modalities.

This is a 2020 ARVO Annual Meeting abstract.

 

FLIO lifetime and fundus autofluorescence (FAF) intensity images from a 45-year-old patient with choroideremia (CHM). FLIO lifetimes are shown in the short (498-560 nm, SSC) and long (560-720 nm, LSC) spectral channel. FLIO lifetimes differ from FAF images.