Abstract
Purpose :
To determine extension and configuration of vascular and fibrous components of choroidal neovascularization (CNV) lesions and the RPE by multimodal imaging.
Methods :
30 eyes of 30 consecutive patients with a minimum history of 12 months of anti-VEGF treatment for neovascular age-related macular degeneration (AMD) were included in this cross-sectional study.
Patients were imaged using a swept-source optical coherence tomography angiography (OCTA) device for comprehensive evaluation of the neovascular complex. Furthermore, a novel polarization-sensitive OCT (PS-OCT) system with an integrated eye-tracker was used to automatically segment fibrous components of the lesion as well as the RPE based on tissue-specific contrast. Microperimetry with color fundus photography was performed for functional mapping. After co-registration of OCTA and PS-OCT scans, location, size and density of vessels were assessed and compared to the configuration of fibrosis and the condition of the RPE.
Results :
Of 30 eyes included in the study, 18 eyes were diagnosed with fibrosis based on clinical examination and PS-OCT imaging. Neovascular nets were preserved within areas of subretinal fibrosis in all eyes and the area of fibrosis matched the center of the CNV in 89% of cases (16/18). Furthermore, fibrosis was observed adjacent to medium and large sized vessels rather than small sized vessels (i.e. capillaries). Vascular channels could be localized anterior to fibrosis (2 eyes; 11%), posterior to fibrosis (9 eyes; 50%) or sandwiched within fibrotic components (7 eyes; 39%). An intact RPE layer was observed in 2 eyes (11%), a discontinuous RPE layer in 4 eyes (22%) and atrophy of RPE was observed in 12 eyes (67%) in the area of fibrosis. However, clusters of RPE cells within the fibrotic complex were observed in all cases.
Conclusions :
Multimodal imaging enables precise identification of spatial correlation of vascular channels and fibrotic and RPE components in CNV lesions. Fibrosis has a predilection to develop in the center (=the presumably oldest component) of the CNV lesion surrounding the medium and large vessels. The RPE layer is mostly absent in areas of fibrosis with residual RPE clusters suggesting a transdifferentiation of RPE cells to myofibroblasts.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.