It’s been known for some time that cataract surgery reduces intraocular pressure (IOP), even without a minimally invasive glaucoma surgery included. But how does that translate to real-world changes in medication use? A recent study reported glaucoma patients sharply reduced their ocular hypertensive meds for five years following cataract surgery. However, noncompliance may account for at least some of the effect.

Researchers analyzed medications dispensed for 440 glaucoma patients before and after bilateral cataract surgery, by using the Taiwan National Health Insurance Research Database. The investigators considered the total number of glaucoma drugs prescribed within one year before the first cataract surgery and one year after the second eye’s surgery.

The study included more than twice as many patients with angle-closure glaucoma (68.6%) than those with open-angle glaucoma (31.4%). Researchers found IOP-lowering meds reduced on average by half after cataract surgery in patients with open-angle glaucoma, from 12 bottles to six. Those with angle-closure glaucoma fared even better, cutting from 10 bottles to three.

Patients with angle-closure glaucoma who were prescribed a greater number of medications had a significantly larger reduction in medication following cataract surgery, and females in the open-angle glaucoma group saw a larger reduction in medication, as did individuals treated in clinics and those who took a higher dose of glaucoma meds.

Although the drop in medication use “was significantly larger in patients with angle-closure glaucoma than in those with open-angle glaucoma, the reduction was sustained for five years in both types of glaucoma,” the researchers said in the study.

The authors were quick to caution against overestimation of the findings. The study only looked at Rx trends, not IOP levels or exam findings. It’s possible, they speculate, that the visual gains from cataract removal encouraged noncompliance with medication use and routine eye care, leading to an inadvisable decline in prescriptions filled. “Our study findings do not imply that cataract removal is a substitute for glaucoma medication in glaucoma management,” they emphasized.

Chang PY, Wang JY, Chang SW, et al. Changes in ocular hypotensive drug usage for glaucoma treatment after cataract surgery: a nationwide population-based study in Taiwan. J Glaucoma. 2018 Jul;27(7):600-5.