When patients were prescribed bisphosphonates more often than the average osteoporosis patient, they were at a higher risk for acute angle closure glaucoma, especially if they took risedronate. Photo: MacLeods Pharma. Click image to enlarge.

A research team from Canada recently published their findings on the risk of glaucoma with bisphosphonate use in patients with osteoporosis in the scientific journal Nature.¹ Their motive for conducting the study was the lack of large epidemiologic studies on the subject, even after two case reports from the last decade have suggested that bisphosphonate use could possibly be linked to acute angle closure and open-angle glaucoma.^2,3 What the researchers discovered was that these topical agents increased the risk of ocular disease, particularly when patients were using specific formulations of the drug.

This case-control study analyzed health claims from 2008 to 2018 to identify patients with osteoporosis who were prescribed bisphosphonates. A total of 208,111 patients taking the drug were included in this study. When analyzing for acute angle closure glaucoma, the researchers identified 372 cases and 1,488 corresponding controls. Then, when analyzing for open-angle glaucoma, the researchers identified 3,184 cases and 12,736 corresponding controls. These patients were selected for their drug regimens, as they were prescribed bisphosphonates at least once every three months for a year prior to the first glaucoma event.

The researchers found patients who used a biphosphonate drug (of any kind) had an adjusted odds ratio for angle closure glaucoma development of 1.78; among those using the drug risedronate, it was even higher at 2.12.

“This is the first population-based study to investigate the association between bisphosphonate use and acute angle closure as well as open-angle closure,” said the researchers in their paper on this study. “Our study found that bisphosphonate use was significantly associated with an increased risk for acute angle closure, being risedronate in particular the only significantly associated agent in multivariate analysis.” They did not find any association between topical drug use and open-angle glaucoma.

While conducting their study, the researchers ran into some limitations. There was a lack of information regarding patients’ diagnoses for glaucoma, their bisphosphonate prescription strengths and background history. Additionally, the database the researchers used was meant for general practice, so ICD-9/10 codes for other predisposing factors may have not been properly catalogued. The researchers suggest further studies will need to be conducted to better understand whether patients are at a greater risk for acute angle closure when taking bisphosphonates.

“The results from our study will have important public health implications as millions of patients around the world use bisphosphonates for osteoporosis treatment,” the researchers wrote. “Physicians prescribing bisphosphonates should discuss the risk of acute angle closure with their patients when reviewing the side effect profile and also inquire on the use of bisphosphonates when evaluating patients with acute angle closure.”