Cataract in Diabetes; The Reykjavik Eye Study

Abstract

Purpose: : To examine cataract prevalence, five–year incidence and rate of surgical treatment in diabetic and non–diabetic participants of the Reykjavik Eye Study (RES).

Methods: : Of the 1045 subjects who participated in the RES in 1996, 846 (376 males and 470 females, Mean age 69.1±9.0 yrs old) or 88.2% of the 959 survivors were reexamined five years later in 2001. Classification of the three main types of opacity was determined from photographed images using the WHO classification system. Eyes which underwent cataract surgery prior to the first RES were excluded. A questionnaire collecting information regarding diabetes, age, gender, smoking, alcohol consumption, systemic steroid and cataract surgery during this five year follow–up period was administered. Data was analyzed using a logistic regression model.

Results: : We found 74 cases of diabetes (8.7%). In non–diabetics vs. diabetics, the percentages of cortical, nuclear and posterior subcapsular cataracts were 29.8 vs. 45.5%; 18.0 vs. 10.6% and 5.2 vs. 8.1%. Five year incidences were 16.2 vs. 33.9%; 9.0 vs. 6.3% and 4.3 vs. 7.7%. Five year cataract surgery rates were 5.3 vs. 8.1%. Subjects with diabetes showed higher cortical cataract prevalence (relative risk 1.63; 95% confidence interval 0.93–2.84; P=0.09) and significantly higher incidence (rr 2.30; 1.23–4.18; p<0.01). The incidence of nuclear cataract was significantly lower in the diabetes group (rr 0.32; 0.12–0.75; P=0.01). The incidences of posterior subcapsular cataract and cataract surgery were not significantly different between the groups.

Conclusions: : Diabetes patients in Iceland had increased risk of cortical cataract and lower risk of nuclear cataract progression. The increased risk of cortical cataract in diabetics concurs with findings of previous epidemiologic studies. Some aspect of diabetes may protect against nuclear cataract.

Keywords: cataract • diabetes • clinical (human) or epidemiologic studies: prevalence/incidence