Possible protective role of cannabis in preventing postoperative proliferative vitreoretinopathy after retinal detachment repair

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Long-term cannabis use might play a role in reducing proliferative vitreoretinopathy (PVR) development,¹ according to first author Ahmed M. Alshaikhsalama, MD. He is from the Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas.

He and his colleagues emphasized the importance of this effect. “PVR is the leading cause of rhegmatogenous retinal detachment (RRD) repair failure, affecting up to 10% of cases.^2-5 Despite modern surgical advances in instrumentation and technique, PVR continues to pose a major risk during the postoperative period,⁶” they commented.

They went on to explain that while “prophylactic and therapeutic initiatives have fallen short, efforts have been made to identify patients at particularly elevated risk for developing PVR to aid in preoperative counseling. Increased age, cigarette smoking, globe trauma, vitreous hemorrhage at the time of repair, and myopia are all established risk factors.^2,7,8

They undertook this study because the potential risk associated with the use of cannabis in the development of PVR remains unknown, while those associated with cigarettes have been identified.^7,9,10

Alshaikhsalama and colleagues explained that the Cannabis sativa plant and its primary active compound tetrahydrocannabinol have been used as a natural anti-inflammatory for centuries.¹¹ Animal models have shown that cannabis reduces microglial activity, inflammatory cytokine expression, and retinal neurotoxicity through action on adenosine and cannabinoid receptors.^12-14 However, cannabis is also associated with the potential risk for exacerbating various ophthalmic conditions that include thyroid eye disease, dry eye syndrome, and neuroretinal dysfunction.^15,16

Cannabis study design and results

This retrospective cohort study included patients who had undergone primary repair of retinal detachment with pars plana vitrectomy with or without use of a scleral buckle (SB), primary SB, or pneumatic retinopexy. The study goal was to assess the risk of development of PVR when the patients were using cannabis concomitantly.

Electronic health records were searched from February 1, 2005, to February 1, 2025, to identify patients diagnosed with concomitant cannabis-related disorder together with confirmatory testing of cannabis in urine or blood compared with a control group without documented use, the investigators recounted.

The primary outcome was the relative risk (RR) of developing PVR and requiring a subsequent complex retinal detachment repair at 6 months and 1 year of follow-up.

The patient and controls groups each included 1,193 participants (mean age, 53.2 years; 69.7% men).

“At 6 months, the patients with concomitant cannabis use with a retinal detachment repaired by any method had a reduced risk of developing subsequent PVR (25 events [2.10%] versus 52 events [4.36%]; RR, 0.48; 95% confidence interval [CI], 0.30-0.77; P = 0.002) and requiring complex RD repair (37 [3.10%] versus 60 [5.03%]; RR, 0.62; 95% CI, 0.41-0.92; P = 0.02) compared with controls,” the authors reported. Similar results also were observed at the 1-year time point for both outcomes.

Alshaikhsalama and colleagues speculated that the anti-inflammatory, wound healing, and antifibrotic effects of cannabis may help explain the lower PVR rate observed in this study.^17-20

The authors concluded, “We observed a reduced risk of developing PVR and need for complex retinal detachment repair up to 1 year after primary RD surgery among patients with long-term cannabis use compared with a matched control cohort. This is the first such study to examine a potential relationship between long-term cannabis use and subsequent PVR. While cannabis use demonstrated a lower RR for PVR, the small absolute reduction (~2%) may not be clinically meaningful. Confounders may account for all the observed associations. Future prospective studies are required to further clarify and characterize the effect of long-term cannabis use on PVR development and management.”

References

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2. Girard P, Mimoun G, Karpouzas I, Montefiore G. Clinical risk factors for proliferative vitreoretinopathy after retinal detachment surgery. Retina. 1994;14:417-424. doi:10.1097/00006982-199414050-00005

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