Pneumatic Vitreolysis for Vitreomacular Traction
Ophthalmology, November 2021
If proven safe and effective, pneumatic vitreolysis (PVL) would be an alternative to vitrectomy that is less invasive and more economical. Chan et al. conducted two multicenter trials to assess the safety and efficacy of PVL for symptomatic vitreomacular traction (VMT), with or without macular hole (MH). Although PVL induced release of the hyaloid membrane in most study eyes, leading to hole closure in about one-third of eyes with full-thickness MH (FTMH), both trials were terminated early due to safety concerns.
The two trials involved 28 study sites. Both studies included adults with central VMT (vitreomacular adhesion ≤3,000 μm) but otherwise proceeded as follows:
- Protocol AG enrolled 46 patients (46 eyes) without FTMH who were assigned randomly to receive PVL (n = 23) or observation plus sham injection (n = 22). Visual acuity (VA) of the eyes in this study ranged from 20/32 to 20/400.
The main outcome was VMT release by 24 weeks; this was achieved without vitrectomy in 18 eyes treated with PVL and in two eyes in the sham group (adjusted risk difference, 66%; p < .001). The mean VA change from baseline to week 24 was 6.7 letters in the PVL arm and 6.1 letters in the sham arm (adjusted difference, –0.8; p = 0.77).
- Protocol AH enrolled 35 patients (35 eyes) and was a single-arm study of PVL for FTMH. Treated eyes had an FTMH measuring ≤250 μm at the narrowest point, and VA in this group ranged from 20/25 to 20/400. PVL was performed with perfluoropropane (C3F8) gas.
The main outcome was FTMH closure by eight weeks; this was attained in 10 (29%) of the 35 eyes, without need for rescue vitrectomy. The mean change in VA from baseline to week 8 was –1.5 letters.
Rates of rhegmatogenous retinal detachment (RRD) or tear were higher than expected in both studies, leading to early termination. Overall, seven eyes (two in Protocol AG and five in Protocol AH) treated with PVL had an RRD (n = 6) or retinal tear (n = 1).
It is plausible that the risk of RRD and the indications for PVL may differ for VMT and MH, the authors said. Whether any modification of the PVL injection technique could reduce the risk of retinal detachment is not known and may be a topic of future research.
The original article can be found here.