Chan C, et al. A randomized clinical trial of pneumatic vitreolysis with C3F8 for vitreomacular traction and a single-arm study of pneumatic vitreolysis with C3F8 for macular hole: DRCR Retina Network Protocols AG and AH. Presented at: Association for Research in Vision and Ophthalmology annual meeting; May 1-7, 2021 (virtual meeting).
Chan reports he receives research funding from Allergan, Roche/Genentech, Regeneron, Amgen and Iveric.
Two DRCR.net studies investigating pneumatic vitreolysis in vitreomacular traction and macular hole showed relatively good efficacy but were terminated before completion due to safety concerns.
“Pneumatic vitreolysis (PVL) is an in-office procedure for vitreomacular traction (VMT) and macular hole involving injection of an expansile gas such as C3F8,” Clement Chan, MD, said at the virtual Association for Research in Vision and Ophthalmology meeting. “If found to be safe and effective, PVL would be a less invasive, lower-cost alternative to vitrectomy.”
Two DRCR.net studies evaluated the safety and efficacy of PVL for symptomatic VMT without macular hole (Protocol AG) and with macular hole (Protocol AH). Protocol AG was a randomized clinical trial comparing PVL with sham injection in eyes with VMT less than 3,000 µm in adhesion length and no full-thickness macular hole. Protocol AH was a single-arm study assessing PVL for closure of full-thickness macular hole no more than 250 µm wide at the narrowest point. Baseline standardized visual acuity was required to be between 20/32 and 20/400 in AG and between 20/25 and 20/400 in AH.
In AG, 46 eyes (37% of the recruitment goal) were included. Central VMT release without rescue occurred in 78% of the PVL group and only 9% of the sham group. In AH, 35 eyes were recruited (70% of the recruitment goal), and macular hole closure without rescue vitrectomy occurred in 29% of eyes, while 34% required rescue vitrectomy. Mean best corrected visual acuity improved by 9.2 letters, with 53% of eyes gaining 10 or more letters.
In both studies, recruitment was placed on hold after seven eyes developed retinal detachment or retinal tears. It was resumed following literature review and revision of the informed consent form, but after two further cases, resulting in a combined 12% rate of tears and detachment, the data and safety monitoring committee recommended termination of recruitment.
“These studies are too small and the follow-up is too short to make definitive conclusions,” Chan said. “However, despite higher than expected rate of retinal tears and detachment, some patients and physicians may still consider PVL for treating VMT and MH.”