Systemic Inhibition of the Angiotensin System Associated with Reduced Rates of Glaucoma Surgery

Authors: James J. Armstrong¹, Vinay Kansal¹, Jacqueline Slomovic², Anastasiya Vinokurtseva¹, Blayne Welk¹, Cindy M. L. Hutnik¹. ¹Schulich School of Medicine, ²University of Toronto.

Author Disclosures: J.J. Armstrong: None. V. Kansal: None. J. Slomovic: None. A. Vinokurtseva: None. B. Welk: None. C.M.L. Hutnik: None.


Abstract Body: 

Purpose: Glaucoma has been associated with blood pressure dysregulation, and the use of anti-hypertensive agents with reduced glaucoma incidence and progression risk. Recent work suggests that angiotensin-modulating agents may have the most significant neuroprotective effect. This study assesses the time from initial medical or laser glaucoma treatment to first incisional surgical intervention in patients on angiotensin-modulating therapy compared to other anti-hypertensive therapy or no anti-hypertensive therapy. 

Study Design: Retrospective cohort study using ICES database. 

Methods: Patient records with an initial glaucoma medical or laser therapy between July 1996, and March 2009 were identified, and grouped by anti-hypertensive medication exposure: 1) no anti-hypertensive, 2) angiotensin-modulating therapy, or 3) other anti-hypertensive medication. Records were followed up to 25 years after diagnosis and examined for instances of incisional glaucoma surgery. The primary outcome was time to surgical intervention from initial glaucoma medical or laser treatment. A multivariable Cox proportional hazards model was used to calculate the hazard ratio of undergoing glaucoma surgery based on anti-hypertensive medication exposure and baseline characteristics. 

Results: Records from 25,146 glaucoma patients were included, with 4,371 (17.4%) undergoing initial treatment with SLT and 20,775 (82.6%) receiving primary medical therapy. There were 12,591 (54.1%) patients on no anti-hypertensive therapy, 4,304 (17.1%) on angiotensin-modulating therapy such as angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB), and 7,251 (28.8%) on calcium channel blockers (CCB) or diuretics. The groups were well balanced in terms of age, sex, and comorbidity score. After 10 years follow up, the absolute event rate was 10.5% in the unexposed cohort, 7.6% in the ACEi/ARB exposure cohort, and 11.5% in the CCB/diuretic cohort. Compared to patients on angiotensin-modulating therapy, glaucoma patients without exposure to anti-hypertensive therapy underwent glaucoma surgery significantly more frequently (HR 1.2; 95%CI 1.1-1.4), whereas CCBs/diuretics did not have a significant associated hazard (HR 1.1; 95%CI 0.96 - 1.28). 

Conclusions: Blood pressure control is an important consideration in glaucoma management. A significant reduction in the rate of glaucoma surgical intervention was associated with angiotensin-modulating therapy among patients diagnosed with glaucoma. Further studies are warranted to elucidate a causal relationship between blood pressure dysregulation, antihypertensive therapy, and glaucoma progression.

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