Long-term Cannabis Use May Offer Protective Benefit Against PVR Development

PVR involves irregular proliferation of cells that form contractile membranes on, within or under the retina. Photo: Rami Aboumourad, OD. Click image to enlarge. Proliferative vitreoretinopathy (PVR) is the leading cause of failure of rhegmatogenous retinal detachment (RD) repair, accounting for around 5% to 10% of all such outcomes. As study of the factors influencing RD repair success or failure remains important, researchers sought to elucidate the relationship between long-term cannabis use and subsequent PVR. Their work was published last week in JAMA Ophthalmology. The retrospective design included electronic health records for a multicenter research network over a 20-year period; patients were those who underwent initial RD repair with pars plana vitrectomy with or without scleral buckle, primary scleral buckle or pneumatic retinopexy. Records were used to identify those with documented concomitant cannabis-related disorder, taken together with confirmation of testing of cannabis in urine or blood, compared to a control group with no documented use.Propensity score matching was used, resulting in 1,193 patients assigned in each cohort. Mean age was 53.2 and 69.7% of subjects were male. Concomitant cannabis use with RD repaired by any method was found at six months to result in reduced risk of developing subsequent PVR (2.1% vs. 4.4%) as well as reduced need for complex RD repair (3.1% vs. 5.0%) when compared to the controls. Both outcomes reflected similar results observed at the one-year mark, too.The authors elaborate in their discussion of the paper on why this reduction in risk may manifest. Other investigations have already documented cannabis possesses beneficial antifibrotic and wound healing modulation effects. Related to this, PVR development is also linked with abnormal wound healing, prompting the authors to believe that “given these potential associations, the anti-inflammatory, wound healing and antifibrotic effects of cannabis may help explain the lower PVR rate observed in this study.”1Although the results are promising in establishing a link between the two, the investigators do note that “while cannabis use demonstrated a lower relative risk for PVR, the small absolute reduction (~2%) may not be clinically meaningful.”1This sentiment is echoed in an invited commentary also published to JAMA, in which commentators point out that, despite the potential therapeutic benefits of cannabis and its derivatives, consideration should be given to the challenges linked with their clinical use.One such issue with the investigation is that the original authors noted the cannabis group had higher rates of cigarette use (41.5% vs. 5.1%), myopia (18.5% vs. 7.8%), intraoperative vitreous hemorrhage (12.6% vs. 5.9%) and ocular trauma (15.2% vs. 3.7%), all of which are factors known to increase PVR risk. Although propensity score matching ensured comparable treatment and a control group, it can’t account for unknown covariates and confounders, which could reduce generalizability of results. These could include size, duration and macular status—all characteristics of RD—as well as quantity and duration of cigarette use, recent or remote ocular trauma and myopia. What’s more, quantifying dose or concentration, duration and route of cannabis use is difficult.The commentators also highlight that cannabis has other detrimental effects documented, such as increased risk for cardiopulmonary disease and psychiatric conditions of psychosis, anxiety, depression and suicidal ideation. The original study even reported that the long-term cannabis users had greater incidence of emphysema, acute or chronic bronchitis, gastroesophageal reflux disease, cardiac arrhythmias and anxiety disorders.In the future, “particular attention should be given to identifying and isolating the active ingredients in cannabis that protects against PVR, with the goal of developing a targeted therapy with fewer adverse effects in the future,” the commentators argue.Click here for the study and here for the commentary.  1. Alshaikhsalama AM, Alsoudi AF, Mukhtar A, et al. Long-term cannabis use and risk of postoperative proliferative vitreoretinopathy. JAMA Ophthalmol. July 3, 2025. [Epub ahead of print].2. Groothoff JD, Ong SS. Cannabis use and proliferative vitreoretinopathy risk reduction. JAMA Ophthalmol. July 3, 2025. [Epub ahead of print].