Is cannabis protective against proliferative vitreoretinopathy after retinal detachment repair?

Cannabis users who underwent initial repair for retinal detachment (RD) appear to be at lower risk of developing proliferative vitreoretinopathy and, in turn, requiring subsequent complex RD repair when compared with their nonuser peers, according to a retrospective study.

Researchers used data from a multicentre research network and identified patients who had undergone initial RD repair with pars plana vitrectomy with or without scleral buckle (SB), primary SB, or pneumatic retinopexy. Patients with concomitant cannabis use were matched to those without documented use using propensity score.

The study included 1,193 patients each in the cannabis group and the control group. The mean age overall was 53.2 years, and 69.7 percent were male.

At 6 months, significantly fewer patients in the cannabis group than in the control group developed subsequent proliferative vitreoretinopathy (2.10 percent vs 4.36 percent; relative risk [RR], 0.48, 95 percent confidence interval [CI], 0.30–0.77; p=0.002) and required complex RD repair (3.10 percent vs 5.03 percent; RR, 0.62, 95 percent CI, 0.41–0.92; p=0.02).

The 1-year results for both outcomes were similar.

The findings point to the potential role of cannabis in reducing the risk of proliferative vitreoretinopathy development. However, researchers acknowledged that the protective association could be due to the population using it rather than an effect of the cannabis itself. More studies controlling for confounding factors are needed.