En-face Optical Coherence Tomography to detect and quantify Geographic Atrophy

Abstract

 

Purpose

 

To evaluate the possibility to detect and quantify geographic atrophy (GA) secondary to age-related macular by means of en-face spectral-domain optical coherence tomography (en-face OCT) and to compare the GA area to that obtained by means of fundus autofluorescence (FAF).<br />

 

Methods

 

Twenty-four consecutive patients (27 eyes) affected by GA were studied by means of en-face OCT. Both standard (automatic retinal tracking, ART) and enhanced depth imaging (EDI) scanning modalities were performed. The GA areas were measured both on the en-face OCT imaging at the outer retinal (OR) layer and at the choroidal (CH) layer. These areas were compared with the GA areas measured by FAF images. Both short-wavelenght FAF (SW-FAF) and near infrared-wavelenght FAF (NIR-FAF) imaging modalities were performed.<br />

 

Results

 

The intra- and inter-operator agreement in the GA area measurement was excellent at the en-face OCT imaging at the OR layer (ICC= 0.99 in EDI, 0.98 in ART and 0.97 in EDI, 0.98 in ART, respectively). Good concordance was found analyzing the en-face OCT imaging at the CH layer. GA areas measured with both FAF imaging modalities were significantly correlated to those calculated in the en-face SD-OCT imaging at the OR layer level (SW-FAF vs ART-OR and NIR-FAF vs EDI-OR, p=0.0057 and p=0.0036, respectively).<br />

 

Conclusions

 

En-face OCT is a reliable method for the detection and the quantification of GA, particularly when analyzed by means of the en-face OCT imaging at the outer retina, where the loss of photoreceptor layer creates an abrupt transition in OCT reflectivity.<br />