OCTA Reveals Another New Phenomenon in the Retinal Vasculature
By Nadia Waheed, MD, MPH
The debut OCT Angiography eUpdate predicted that OCTA would become an important tool for clinical trials and indeed it has. This technology adds the ability to discover and evaluate biomarkers in the retinal vasculature that had not been detectable or reliably measured by any other means. Such biomarkers can be used to elucidate disease pathophysiology and assess the impact of therapies. OCTA alerted us to the phenomenon of non-exudative choroidal neovascularization (CNV) and, more recently, has revealed the existence of vascularized drusen. Both entities are being observed as part of the PRO-CON study.1,2
The purpose of PRO-CON is to determine whether quarterly anti-VEGF injections can prevent conversion from dry to wet age-related macular degeneration (AMD) in high-risk eyes, i.e., eyes with a diagnosis of non-exudative AMD based on drusen and pigmentary changes and a fellow eye with exudative AMD based on leakage on fluorescein angiography (FA) and fluid on OCT. One-year data from the study were recently analyzed and presented.1 No statistically significant difference in the rate of conversion was observed between the group that received prophylactic anti-VEGF treatment and the group that received sham. However, PRO-CON will continue to its planned two-year endpoint, and the vascularized drusen that were observed in some of the patients will continue to be monitored with OCTA.
Further study of the vascularized drusen in PRO-CON should help determine how early in the course of AMD neovascularization appears and whether vascularized drusen increase the risk of conversion to wet AMD. OCTA was included in PRO-CON to validate how well and how much earlier the technology can detect CNV and other pathologic changes compared with OCT and FA. While these questions have been previously examined and reported on, this is the first time a study has investigated them systematically. The collected data will be valuable going forward as additional exploratory endpoints emerge.
1. Brown DM. OCT-angiography results from the PRO-CON study: intravitreal aflibercept injection (IAI) versus sham as prophylaxis against conversion to neovascular age-related macular degeneration (nAMD) in high-risk eyes. RET17 Section XIII: Late Breaking Developments, Part II. Retina Subspecialty Day/American Academy of Ophthalmology annual meeting; Oct 27, 2018, Chicago, IL.
2. A Prospective, Single-Blind, Randomized Study to Evaluate Intravitreal Aflibercept Injection (IAI) Versus Sham as PROphylaxis Against CONversion to Neovascular Age-Related Macular Degeneration (AMD) in High-Risk Eyes. ClinicalTrials.gov Identifier: NCT02462889. Available at: https://clinicaltrials.gov/ct2/show/NCT02462889; accessed Dec. 12, 2018.
Dr. Waheed is a vitreoretinal specialist and director of the Boston Image Reading Center at New England Eye Center. She is also an associate professor of Ophthalmology at Tufts University School of Medicine in Boston. Dr. Waheed teaches medical students, ophthalmology residents, retina fellows, research fellows, and PhD and post-doctoral students.