To evaluate, both at initial glaucoma diagnosis and during treatment, the role of demographic and clinical factors on intraocular pressure (IOP).
Cohort study of patients enrolled in a randomized clinical trial.
607 patients with newly diagnosed, open-angle glaucoma (OAG) were enrolled at 14 U.S. centers.
After randomization to initial surgery or medications, patients were followed at six-month intervals. IOP was measured by Goldmann applanation tonometry. Predictive factors for IOP at baseline and during follow-up were analyzed using linear mixed models.
Main Outcome Measure
IOP at baseline and during follow-up.
The mean baseline IOP was 27.5 mmHg (standard deviation, 5.6 mmHg). Predictive factors for higher baseline IOP included younger age (0.7 mmHg per 10 years), male sex (2.4 mmHg higher than females), pseudoexfoliative glaucoma (5.4 mmHg higher than primary OAG), and pupillary defect (2.2 mmHg higher than those without a defect). During nine years of follow-up, both surgery and medications dramatically reduced IOP from baseline levels, but the extent of IOP reduction was consistently greater in the surgery group. Over follow-up years 2–9, mean IOP was 15.0 vs. 17.2 mmHg for surgery vs. medicine, respectively. Predictive associations with higher IOP during follow-up included higher baseline IOP (P<0.0001), worse baseline visual field (mean deviation; P<0.0001), and lower level of education (P=0.0019). Treatment effect was modified by smoking status: non-smokers treated surgically had lower IOP than smokers treated surgically (14.6 vs. 16.7 mmHg, respectively; P=0.0013). Clinical center effects were significant (P<0.0001) in both the baseline and follow-up models.
In this large cohort of newly diagnosed glaucoma patients, predictors of pre-treatment IOP and IOP measurements over nine years of follow-up were identified. Our findings lend credence to the postulate that sociodemographic, economic, compliance, or other environmental influences play a role in IOP control during treatment.