Optical coherence tomography difference maps and average macular volume for geographic atrophy.

PURPOSE: To demonstrate the ability to monitor geographic atrophy (GA) volumetrically through all retinal layers with high-resolution optical coherence tomography difference maps and average macular volume.
METHODS: Observational case report.
RESULTS: Two patients diagnosed with GA were followed up for multiple years with consecutive high-resolution optical coherence tomography studies along with fundus photography and fluorescein angiography or fundus autofluorescence. Difference maps visually reflect macular thinning associated with expansion of GA witnessed on alternative studies. In addition, these maps show progressive macular thinning within previously delineated areas of GA. Average macular volume quantitatively demonstrates the decreasing volume associated with the expanding atrophy.
CONCLUSION: Difference maps and average macular volume allow quantitative analysis of GA and may be a useful tool for patient care and clinical trials.