A cataract is a clouding of the lens in the eye leading to decreased vision. Cataracts occur most commonly due to aging, but may also be due to trauma or a complication of eye surgery for other problems (e.g., glaucoma). Risk factors include diabetes (a disease of high blood sugar levels over a prolonged period), smoking tobacco, prolonged exposure to sunlight, and alcohol consumption. We are especially interested in cataract development in diabetic patients (type I and type II) and in those patients who already developed a complication of their diabetes such as diabetic retinopathy (malfunctioning of a light-sensitive layer in the eye) or macular oedema (i.e., fluid accumulation close to that light-sensitive layer called retina). Scientific reports on cataract rates in these populations are scarce.
Additionally, we will characterise diabetic cataract patients with respect to potential risk factors for their cataract and compare occurrence of those risk factors in diabetics who have not yet developed a cataract.
The study aims to describe the incidence of cataract in patients with diabetes mellitus in the UK and compare it (stratified by age, sex and year of diagnosis) to a random sample of the general (non-diabetic) population. Furthermore, we will calculate incidence rates of cataract in subpopulations of patients with diabetic retinopathy or macular edema.
We will use COX proportional hazards modelling (adjusted for age, gender and index year of diabetes diagnosis) to assess time to cataract in newly diagnosed diabetic patients.
Additionally, we will carry out a nested case-control analysis in diabetic patients with or without cataract to identify risk factors for cataract development. We will perform conditional logistic regression analysis using SAS software.
Health Outcomes to be Measured:
Incidence rates of cataract in patients with a diabetes diagnosis
Hazard ratio of cataract associated with a diabetes diagnosis
Odds ratio for cataract associated with diabetes duration, HbA1c, exposure to antidiabetic drugs