Adaptive optics (AO) retinal imaging delineates retinal changes in patients at all ETDRS stages of diabetic macular ischemia, undetectable by other structural and functional imaging in mild to moderate ischemia.

Abstract

Purpose : To assess the retinal changes detected with AO imaging, spectral-domain optical coherence tomography (SD-OCT) and microperimetry in patients at varying stages of ETDRS diabetic macular ischemia.

Methods : We performed AO imaging of retinal mosaics with the rtx-1 camera (Imagine Eyes, Orsay, France) at 6 ROIs of 4 eyes (3 patients) with diagnosis of macular ischemia on fundus fluorescein angiography (FFA). AO images were registered to corresponding SD-OCT scans, FFA and microperimetry. Cone metrics were cone density index (Cdi): percentage of ratio of cone density in disease/healthy eyes in age-matched individuals and hexagonal packing index (Hi) was measured and correlated to microperimetry and inner segment – ellipsoid (ISel) band.

Results :
In severe DMI (stage 4) there was significant reduction in cone metrics; Cdi and Hi, which correlates with complete loss of retinal sensitivity, but only minimal disruption of ISel band.
In moderate DMI (stage 3) there was moderate loss of retinal sensitivity, with corresponding reduction in cone metrics; Cdi and Hi but no disruption of ISel band.
In mild DMI (stage 2) there was no loss of retinal sensitivity, no disruption of ISel band but reduction in cone metrics; Cdi and Hi was observed.

Conclusions : This DMI study shows ability of AO imaging to deep-phenotype the cone photoreceptor changes at mild and moderate levels of ischemia, which were undetectable on SD-OCT. The cone structural changes were detected by AO imaging but not functionally by microperimetry in mild ischemia, though AO cone metrics correlate highly with functional changes detected on microperimetry in moderate to severe ischemia.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

(A) Fundus image with fluorescein angiogram overlay (area of ischemia bounded by purple line, with enlargement of foveal avascular zone) and overlay of retinal microperimetry (data in dB units). Blue bounded box corresponds to area of adaptive optics (AO) imaging
(B) AO image at regions of interest (ROI) shows reduction in cone photoreceptors and disruption of mosaic (red box at 1 degree temporal to fovea (1T) in area of ischemia within purple bounds) compared to intact cone photoreceptor mosaic (blue box at 2 degree temporal to fovea (2T))
(C) OCT image shows intact inner-segment ellipsoid band at corresponding 1T (red arrow) and 2T (blue arrow)