En Face Optical Coherence Tomography to Detect and Measure Geographic Atrophy

Abstract

PURPOSE: To detect and quantify geographic atrophy (GA) secondary to age-related macular degeneration using en face optical coherence tomography (OCT) and to correlate it to GA measured with fundus autofluorescence (FAF). METHODS: Twenty-four consecutive patients (27 eyes) were studied with both standard (STD)- and enhanced depth imaging (EDI)-OCT. En face OCT images were obtained at the outer retinal layer (OR) and at the choroidal layer (CH) level for both STD- and EDI-OCT. Areas of GA were measured on the en face OCT images and were correlated with the GA areas measured on blue (B)- and near infrared (NIR)-wavelength FAF images. RESULTS: The intraoperator agreement in GA measurement was excellent with en face OCT at both OR and CH levels (intraclass correlation coefficient [ICC] = 0.99 in EDI and 0.98 in STD at OR level; 0.99 in EDI and 0.99 in STD at CH level). The interoperator agreement was excellent at OR level (ICC = 0.97 in EDI and 0.98 in STD), good at CH level (ICC = 0.95 in EDI, 0.90 in STD). The geographic atrophy area, at both B-FAF and NIR-FAF, was significantly equivalent to the GA area at OR level (B-FAF versus SDT-OR and EDI-OR: P = 0.0057 and 0.0090, respectively; NIR-FAF versus STD-OR and EDI-OR: P = 0.0131 and 0.0036, respectively), but not at CH level. CONCLUSIONS: En face OCT is a reliable method to detect and quantify GA, particularly when analyzed at the OR level, where the photoreceptors' loss creates an abrupt transition in OCT reflectivity.