Quantitative evaluation of type 1 and type 2 choroidal neovascularization components under treatment with projection-resolved optical coherence tomography angiography

Abstract

Purpose : To evaluate the response of type 1 and type 2 choroidal neovascularization (CNV) components under anti-vascular endothelial growth factor (VEGF) treatment in age-related macular degeneration (AMD) using projection-resolved optical coherence tomography angiography (PR-OCTA).

Methods : Eyes with treatment naïve exudative AMD were enrolled in a prospective, year-long longitudinal cohort study while under PRN anti-VEGF injections. Macular PR-OCTA was obtained at baseline, 6-month, and 1-year visit. PR-OCTA signal between outer plexiform layer to Bruch’s membrane generated total CNV angiogram. PR-OCTA signal was further separated by RPE and projected onto type 1 (above RPE) and type 2 (below RPE) CNV angiograms. CNV vascular area was segmented and measured by a convolutional neural network (CNN) based algorithm. Individual CNV were classified as pure type 1 CNV, all vascular area was type 1 CNV component; predominantly type 2 CNV, at least 75% of the vascular area was type 2 CNV component; or mixed type CNV, with type 2 component accounting for 75% or less of the lesion. Change in CNV vascular area between visits were assessed with Friedman’s analysis of variance (ANOVA).

Results : Of 18 total eyes, 13 eyes (72%) were pure type 1 CNV, 2 eyes (11%) were predominantly type 2 CNV, and 3 eyes (16%) were mixed type CNV at baseline. Total CNV vascular area did not change over the 1-year follow-up (P=0.45). CNV vascular area of type 1 increased (P=0.0034), whereas CNV vascular area of type 2 decreased during the 1-year follow-up (P=0.0015). At 6-month and 12-month visit, type 2 CNV was undetectable and all cases were graded as pure type 1 CNV. Of 5 eyes with type 2 CNV component at baseline, 4 eyes (80%) had RPE envelopment which converted type 2 CNV component into a type 1 pattern. CNV vascular area of pure type 1 CNV increased, but not significantly (P=0.0753).

Conclusions : PR-OCTA with CNN based algorithm demonstrated after one year of treatment, all Mixed type CNV and predominantly type 2 CNV converted to pure type 1 CNV. In these eyes, type 1 CNV vascular area increased at one year. Pure type 1 at baseline had non-significant increase in CNV vascular area at one year.

This is a 2021 ARVO Annual Meeting abstract.

 

Representative cases showing baseline and treatment response at one year for pure type 1 CNV (Case 1), predominantly type 2 CNV (Case 2), and mixed type CNV (Case 3).