Quantitative OCT Angiography Parameters Can Help Classify AMD-induced Choroidal Neovascularization

Utilizing optical coherence tomography angiography (OCT-A) imaging could provide information regarding both clinical and functional outcomes after anti-vascular endothelial growth factor (VEGF) treatment in some patients, according to an investigation published in Retina.  The research reviewed patients with choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).

The interventional, prospective case series study recruited a total of 78 patients with AMD who had progressed to CNV from the ophthalmology unit of San Raffaele Hospital in Milan between October 2016 and December 2017, and followed them for 1 year.

All participants underwent a complete evaluation with imaging and researchers compiled several OCT and OCT-A parameters. These included 2 new quantitative parameters; vessel tortuosity (VT) and vessel dispersion (VDisp). Patients then underwent anti-VEGF injections as needed on an individual basis. Researchers then classified CNVs as either occult (found in 45 eyes), classic (14 eyes), or mixed (19 eyes) using fluorescein angiography and indocyanine green. 

The mean best-corrected visual acuity (BVCA) was 20/62 at baseline and improvement to 20/41 at the 1-year follow-up (P =.01). The mean number of anti-VEGF injections was approximately 6.4 injections. OCT-A parameters were examined with respect to classic, occult, and mixed CNV with occult CNV showing the highest different values of VDisp and occult CNV showing the lowest (P =.01). The VT cut-off was 8.40, which enabled 2 patient subgroups to differ significantly in visual outcome after anti-VEGF treatment. Patients with a VT of less than 8.40 demonstrated significantly lower BCVA initially, with significant improvement at follow up. 

Prior research that considered the vascular patterns of new vessels were burdened by key limitations, the investigation reports. In particular, those studies only took qualitative assessments of the CNV into account, relying on subjective image interpretation by an ophthalmologist. This research aims to provide new parameters that use OCT-A to create a quantitative assessment. Researchers hope these can be applied to artificial intelligence for the automated analysis of CNV biomarkers.

Ultimately, the study demonstrates that a baseline OCT-A could offer information for clinical and functional outcomes for post anti-VEGF treatment in CNV that is secondary to AMD. While the researchers explain that further studies are needed, the adaptation of quantitative CNV classification may eliminate subjective evaluation and pave the way for artificial intelligence guided automated assessment. 

Reference

Arrigo A, Romano F, Aragona E, et al. Optical coherence tomography angiography can categorize different subgroups of choroidal neovascularization secondary to age-related macular degeneration. Retina. 2020;40(12):2263-2269. doi:10.1097/IAE.0000000000002775.