Glaucoma incidence in an unselected cohort of diabetic patients: is diabetes mellitus a risk factor for glaucoma?
- John D Ellisa,b,c,
- Josie M M Evansb,
- Danny A Rutac,
- Paul S Bainesa,
- Graham Leesed,e,
- Thomas M MacDonaldb,
- Andrew D Morris for the DARTS/MEMO Collaborationb,d,e
- aDepartment of Ophthalmology, Ninewells Hospital and Medical School, Ninewells Road, Dundee DD1 9SY, UK, bMedicines Monitoring Unit, cDepartment of Epidemiology and Public Health, dUniversity Department of Medicine, eDiabetes Centre
- Dr John EllisJDE{at}14bing.freeserve.co.uk
- Accepted 3 May 2000
Abstract
AIMS To evaluate whether diabetes mellitus is a risk factor for the development of primary open angle glaucoma or ocular hypertension (OHT).
METHODS A historical cohort study of an unselected population comprising all residents of the Tayside region of Scotland was performed using record linkage techniques followed by case note review. Ascertainment of prevalent diabetes was achieved using the Diabetes Audit and Research in Tayside Study (DARTS) validated regional diabetes register. Glaucoma and treated OHT were defined by encashment of community prescriptions and the statutory surgical procedure coding database.
RESULTS The study population comprised 6631 diabetic subjects and 166 144 non-diabetic subjects aged >40 years without glaucoma or OHT at study entry. 65 patients with diabetes and 958 without diabetes were identified as new cases of glaucoma or treated OHT during the 24 month study period, yielding a standardised morbidity ratio of 127 (95% CI, 96–158). Case note review demonstrated non-differential misclassification of prevalent glaucoma and OHT as incident disease (diabetic cohort 20%, non-diabetic cohort 24%; p=0.56) primarily as a result of non-compliance in medically treated disease. Removing misclassified cases and adjusting for age yielded an incidence of primary open angle glaucoma in diabetes of 1.1/1000 patient years (95% CI, 0.89–1.31) compared to 0.7/1000 patient years (95% CI, 0.54–0.86) in the non-diabetic cohort; RR 1.57 (95% CI, 0.99–2.48).
CONCLUSIONS This study failed to confirm an association between diabetes mellitus and primary open angle glaucoma and ocular hypertension. A non-significant increase in diagnosed and treated disease in the diabetic population was observed, but evidence was also found that detection bias contributes to this association.
