Sophie Cai, MD
Vitreoretinal Surgery Fellow
Duke Eye Center, Durham, NC
One of the highlights of today’s session was Dr. Clement Chan’s presentation of the results of the multicenter DRCR Protocols AG and AH.
DRCR.net Protocol AG – Pneumatic Vitreolysis for VMT
Protocol AG was the first randomized controlled trial to assess the safety and efficacy of in-office pneumatic vitreolysis (PVL) with intravitreal injection of expansile gas (0.3 cc of 100% C3F8 gas) vs. sham injection in eyes with symptomatic vitreomacular traction (VMT). Inclusion criteria were VMT ≤3 mm in width on OCT and best-corrected VA ranging 20/32 to 20/400 without lamellar or full-thickness macular hole. In total, 46 eyes were recruited (about 1/3 of the original recruitment goal, due to early termination of the study due to safety concerns about higher-than-expected rate of retinal detachment with PVL.) At baseline, the PVL and sham groups were well-balanced for most demographic and ocular features, except for a higher proportion of African Americans (13%) in the PVL group than in the sham group (0%), and a higher rate of loss of integrity of the ellipsoid zone within the central subfield in the PVL group (63%) compared to the sham group (36%). The majority of patients were female and white, approximately half were phakic. Mean visual acuity was Snellen equivalent of 20/50 in the PVL group and 20/40 in the sham group.
Follow-up visits occurred at 1, 4, 12, and 24 weeks and included VA, OCT, DFE, and in some cases myVisionTrack (Genentech Inc., South San Francisco, CA) shape discrimination hyperacuity. The primary outcome was the proportion of eyes with VMT release at 24-week follow-up without need for rescue vitrectomy. Rescue vitrectomy was considered indicated if VA decreased from baseline by at least 5 letters at two consecutive visits starting at the 4-week visit or 10 letters from baseline at any visit. VMT release was significantly greater in the PVL group than sham group (78% central VMT release with PVL vs. 9% with sham injection, p<0.001). Over half of cases of VMT release occurred within one week of PVL, versus at least 12 weeks in the sham group. In a secondary analysis, VA outcomes and shape discrimination hyperacuity were not significantly different between the groups through the 24-week followup, although loss of ellipsoid zone integrity in the central subfield was significantly less common at final follow-up in the PVL group than sham group (27% vs. 50%; p=0.009).
DRCR.net Protocol AH – Pneumatic Vitreolysis for VMT with Macular Hole
Protocol AH was a prospective, but nonrandomized single-arm study to assess the safety and efficacy of in-office PVL with intravitreal injection of expansile gas (0.3 cc of 100% C3F8 gas) followed by 4 days of face-down positioning for 50% of the day in eyes with symptomatic VMT associated with small full-thickness macular hole (≤250 um). For inclusion in the study, VMT had to be ≤3 mm in width on OCT and BCVA could range between 20/25 to 20/400. In total, 35 eyes were recruited (one of which was ultimately excluded due to incorrect diagnosis; this was 70% of the study recruitment goal, again due to early termination stemming from safety concerns). Most patients were female, white, and phakic; the mean baseline VA was 20/80, and mean macular hole diameter was 79 um. Follow-up visits occurred at 1, 4, 8, and 24 weeks and included VA, OCT, and DFE.
The primary outcome was the proportion of eyes with closure of the macular hole at 8 weeks without rescue vitrectomy. Rescue vitrectomy was permitted after 4 weeks if the macular hole diameter had not improved. Macular hole closed in 29% of eyes with in-office PVL, while 34% of eyes underwent rescue vitrectomy. The mean baseline visual acuity at 24 weeks improved to 20/50. An important conclusion with regards to safety was that 12% of eyes in the PVL group (none in the sham group) developed a retinal tear or detachment. No eyes developed endophthalmitis. One eye in each arm of Protocol AG developed a macular hole. Dr. Chan emphasized the importance of balancing risks and benefits when offering PVL as primary treatment for symptomatic VMT with or without an associated small full-thickness macular hole, and emphasized that both Protocols AG and AH are limited by their small sample sizes and relatively short-term follow-up.