Bilateral evolution of OCT biomarkers in dry AMD: Long-term follow up study

PURPOSE: To report the emergence and progress of four late-stage characteristics: incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) and complete RPE and outer retinal atrophy (cRORA), drusen ooze and drusen collapse in eyes with dry age-related macular degeneration (AMD) using Spectral Domain Optical Coherence Tomography (SD-OCT). METHODS: This was a retrospective analysis of eyes with non-exudative AMD. Multimodal imaging was done at follow up visits ≤ 12 months. OCT volume scan was used to assess and identify the 4 characteristics. Univariate analysis was done for the various demographic and clinical characteristics.Patients with a mean age of 76.7 ± 10 years were followed up for 69.9 ± 20.6 months. iRORA, cRORA, drusen ooze was present in 15.6%, 15.6% and 15.6% of patients at baseline, respectively, and 25.0%, 40.6% and 53.1% of patients at the final follow-up, respectively. At baseline 9.1%, 0% and 9.1% of patients had bilateral drusen ooze, iRORA and cRORA, respectively. By the final follow-up, drusen collapse occurred in 46.9% and 18.8% patients in unilateral and bilateral eyes, respectively.For bilateral cases, the mean interval of time between emergence inthe two eyes for drusen ooze, drusen collapse, iRORA, and cRORA was 5 ± 1.4 years, 2.2 ± 2.2 years, 3.5 ± 0.7 and 1.7 ± 0.6 years, respectively. CONCLUSIONS: Late-stage OCT biomarkers are seen bilaterally at 21.9% at baseline and at 56.3% at 5.8 years follow-up. Once present in one eye, cRORA had the shortest mean interval before appearance in the other eye.