Multimodal Functional And Structural Assessment Of Geographic Atrophy

Abstract

 

Purpose:

 

To correlate retinal function and visual sensitivity with retinal morphology revealed by ultrahigh-resolution imaging with adaptive optics OCT on patients with central and non-central geographic atrophy.

 

Methods:

 

Four patients (mean 69.25±6.24 years) with either central or non-central geographic atrophy were tested. Photopic and scotopic multifocal electroretinograms (mfERGs) were recorded with a DTL electrode from one eye using an eye camera for continuous monitoring of the pupil (Veris Pro and FMSIII, EDI Inc). The stimulus consisted of 98 (200cd/m², photopic) or 61 (-2.5 log cd/m², scotopic) hexagons covering approximately 22^ox22^o (photopic) and 40^ox40^o (scotopic) of retinal area. 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.). The stimulus subtended 20^ox20^o. The eye tracker of the microperimeter identified the preferred retinal locus that was then used for precise targeting of areas for advanced retinal imaging. Images were obtained with purpose-built in-house ultra-high resolution adaptive-optics optical coherence tomography. Auto-fluorescence and color fundus photographs were also acquired.

 

Results:

 

Areas of geographic atrophy showed no light evoked responses with mfERGs and microperimetry. AO-OCT showed that the outer retinal layers are severely disrupted in the atrophic regions. However, electrical responses and sensitivity are restored at the border of the atrophy such that structural and functional maps generally agree. As an example, colour fundus, auto-fluorescence, microperimetry and photopic mfERGs of a 68-year-old female patient are co-registered in the attached image.

 

Conclusions:

 

Functional vision is maintained at the border of the geographic atrophy and the photoreceptors there may now be targeted for detailed structural and functional monitoring.  

 

Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electroretinography: clinical