Hypothyroidism and the Risk of Developing Open-Angle Glaucoma: A Five-Year Population-Based Follow-up Study

Abstract

To investigate the risk of open-angle glaucoma (OAG) after a diagnosis of hypothyroidism. A retrospective, population-based follow-up study using an administrative database. The study group comprised 257 hypothyroidism patients. The comparison group included 2056 subjects. Data were retrospectively collected from the Taiwan Longitudinal Health Insurance Database. The study cohort comprised patients aged ≥ 60 who received a first diagnosis of hypothyroidism (International Classification of Diseases, Ninth Revision, Clinical Modification code 244.9) from 1997 to 2001 (n = 257). The comparison cohort consisted of randomly selected patients without hypothyroidism who were aged ≥ 60 and had no diagnosis of glaucoma before 2001 (8 for every OAG patient; n = 2056). Each sampled patient was tracked for 5 years from their index visit. Cox proportional hazard regressions were used to compute the 5-year OAG-free survival rate, after adjusting for possible confounding factors. The risk of developing OAG during the 5-year follow-up period. Open-angle glaucoma developed in 7.4% of patients with hypothyroidism and 3.8% of patients in the comparison cohort during the follow-up period. Hypothyroid patients had a significantly lower 5-year OAG-free survival rate than patients in the comparison cohort. After adjusting for patients' age, gender, monthly income, urbanization level, and comorbid medical disorders, hypothyroidism patients were found to have a 1.78-fold (95% confidence interval [CI], 1.04-3.06) greater risk of developing OAG than the comparison cohort. This association remained significant in untreated hypothyroidism patients (adjusted hazard ratio [HR], 2.37; 95% CI, 1.10-5.09) and became statistically nonsignificant in patients treated with levothyroxine (adjusted HR, 1.73; 95% CI, 0.89-3.38). Hypothyroid patients had a significantly increased risk of OAG development during the 5-year follow-up period. Levothyroxine seemed to be protective.