Purpose: To investigate the imaging features preceding the occurrence of type 3 (T3) macular neovascularization (MNV) using tracked spectral-domain optical coherence tomography (SD-OCT).
Method: From a cohort of eyes with T3 MNV and ≥ 12 months of prior tracked SD-OCT, T3 lesions that developed above soft drusen were selected for OCT analysis. Retinal imaging findings at the location where type T3 MNV occurred were analyzed at each follow-up until the onset of T3 MNV. The following OCT parameters were assessed: drusen size (height and width), outer nuclear layer (ONL)/ Henle fiber layer (HFL) thickness at the drusen apex, and the presence of intraretinal hyperreflective foci (HRF), retinal pigment epithelium (RPE) disruption, incomplete RPE and outer retina atrophy (iRORA), and complete RORA (cRORA).
Results: From a cohort of 31 eyes with T3 MNV, T3 lesions developed above soft drusen in 20 eyes (64.5%). Drusen showed progressive growth (p<0.001) associated with ONL/HFL (p<0.001) thinning prior to T3 MNV. The following OCT features were identified preceding the occurrence of T3 MNV, typically at the apex of the drusenoid lesion: disruption of the external limiting membrane (ELM)/ellipsoid zone (EZ) and/or the RPE, HRF, and iRORA/cRORA.
Conclusion: Our results demonstrate specific anatomic alterations preceding the occurrence of T3 MNV that most commonly originates above soft drusen. Drusen growth, reduced ONL/HFL thickness, and RPE atrophy at the drusen apex precede the development of T3 MNV. Identifying these OCT features should warrant close monitoring for identification of T3 MNV which can benefit from prompt intravitreal anti-VEGF therapy.
Bousquet E, Santina A, Corradetti G, et al. From drusen to type 3 macular neovascularization. Retina. 2023 https://pubmed.ncbi.nlm.nih.gov/37756671/