Findings and Correlation Between Spectral OCT and Fundus Autofluorescence at the Margins of Geographic Atrophy

Abstract

Purpose: : Increased fundus autofluoresence at the margins of geographic atrophy lesions has been shown to predict progression of this disease. We wished to determine the structural correlates of hyper autofluoresence using Spectral Domain OCT co-localized with simultaneous SLO fundus imaging . We therefore studied the appearance of margins of Geographic atrophy (GA) in high- resolution optical coherence tomography (OCT) images and correlate those changes with fundus auto fluorescence (FAF) imaging.

Methods: : Patients with GA secondary to dry age related macular degeneration (ARMD) were assessed by means of Spectral Domain OCT (Spectralis HRA/OCT; Heidelberg Engineering, Heidelberg, Germany or OTI, Inc, Toronto, Canada) as well as Autofluoresence Imaging (HRA or Spectralis Heidelberg Engineering, Heidelberg, Germany): The outer retinal layer alterations were analyzed in the junctional zone between normal retina and atrophic retina, and correlated with corresponding FAF at all the four margins.

Results: : 23 eyes of 16 patients between 62 years to 96 years of age were examined. In 93.64% of the cases with increased FAF at the margin of the GA, there were corresponding structural alterations at the outer retina leading to irregular margins. In the lesions exhibiting no abnormal FAF, the smooth OCT margins suggest no abnormal accumulation of lipofuscin and thus no changes in the RPE cells (78.38%).There was a significant association between OCT findings and the FAF findings(r=0.67,p<0.0001). Severe alterations of the outer retinal layers at margins on Spectral OCT correspond significantly to increased autofluorescence; Smooth margins on OCT correspond significantly to normal FAF (kappa-0.7348,p<0.0001).

Keywords: age-related macular degeneration • imaging/image analysis: clinical • retina