Multimodal functional and structural assessment of early and intermediate age-related macular degeneration

Abstract

 

Purpose

 

To correlate retinal function, quantified by photopic and scotopic mfERGs and microperimetry, with retinal morphology revealed by adaptive-optics OCT (AO-OCT) imaging of patients with early- and intermediate-stage age-related macular degeneration

 

Methods

 

6 AREDS Category II AMD subjects (69±5 years, mean±1SD), 6 Category III AMD subjects (71±9 years) and 6 age-matched normals (70±6 years) were tested with a battery of functional and structural modalities including photopic and scotopic mfERGs, microperimetry, color fundus and fundus autofluorescence photography, and AO-OCT imaging. The subjects were classified according to their color and autofluorescence fundus photographs. AO-OCT images were obtained with a purpose-built in-house system having 3.5μm isotropic volumetric resolution. Photopic and scotopic mfERGs were recorded with a DTL electrode from one eye using a camera for continuous monitoring of the pupil (Veris, EDI). The stimulus consisted of 103 (200cd/m2, photopic) or 61 (-2.5 log cd/m2, scotopic) hexagons covering an area of ~40ox40o. Central 20o visual fields were assessed with a microperimeter combined with a scanning laser ophthalmoscope for high-resolution confocal retinal fundus imaging (MAIA, CENTERVUE, S.p.A.)

 

Results

 

The AMD subjects showed a range of retino-anatomical changes; pigmentary changes with drusen, drusenoid deposits, extended drusen and other outer retinal changes. Despite decreased VA which might compromised fixation in more advanced AMD eyes we were able to acquire AO-OCT images of high quality that show, in unprecedented resolution, these anatomical changes (Figure1). Functional tests generally agree with retinal changes. There was, however, one case with extended retinal dysfunction that could not be explained by anatomical changes

 

Conclusions

 

AO-OCT offers high-resolution retinal scans showing details of retinal abnormalities not visible with conventional imaging modalities. Correlation with functional tests provides insight into some anatomical retinal abnormalities and consequences for functional losses  

 

AO-OCT line scans of three different AMD subjects in different retinal locations. Each image is the average of five consecutive B-scans. Left image shows typical peripheral drusen, the middle image shows a foveal region with extended separation of the outer retina from RPE, and the right image shows peripheral drusenoid deposits