ABSTRACT

Purpose:

To describe the ocular determinants of diabetic retinopathy(DR) in a multi-ethnic Asian population in Singapore.

Methods:

Data were pooled from 3 population-based, cross-sectional studies of 3280 Malays, 3400 Indians and 3352 Chinese, aged 40-80+ years, living in Singapore. (The Singapore Epidemiology of Eyes Diseases Study) Diabetes was defined in persons with casual plasma glucose ≥200mg/dl (11.1mmol/l), HbA1c >6.5%, self-reported physician-diagnosed diabetes, or the use of glucose lowering medication. Retinal photographs, taken from both eyes, were graded for the presence and severity of DR using the modified Airlie House classification system. Vision-threatening diabetic retinopathy (VTDR) was defined as severe non-proliferative DR, proliferative DR or clinically significant macular edema. Systolic and diastolic blood pressure (SBP and DBP) was measured with a digital automatic blood pressure monitor. Axial length, and anterior chamber depth were measured using the Zeiss IOL master. Intraocular pressure(IOP) was measured with Goldmann applanation tonometry. Ocular perfusion pressure was defined as Systolic and diastolic blood pressure (SBP and DBP) was measured with a digital automatic blood pressure monitor. Mean ocular perfusion pressure (MOPP) = ⅔(mean arterial pressure − IOP), where mean arterial pressure (MAP) = DBP + ⅓(SBP − DBP), systolic perfusion pressure (SPP) = SBP − IOP, and diastolic perfusion pressure (DPP) = DBP − IOP, was calculated.

Results:

2874 persons had diabetes and gradable photos for analysis. (1006 Malays, 1287 Indians, 581 Chinese) The age-standardized prevalence was 28.2% (95%CI 25.9, 30.6%) for any DR, 7.6 (95%CI 6.5, 9.0%) for any macula edema and 7.7% (95%CI 6.6, 9.0%) for VTDR. Those with diabetic retinopathy had lower BMI, higher HbA1c, longer duration of diabetes, higher systolic blood pressure(sBP) lower total cholesterol and were of lower socioeconomic status (based income and housing) (all p<0.05). In multivariate analysis, adjusted for Age, gender, BMI, HbA1c, Systolic BP, duration of diabetes, Income, Housing and education level; independent ocular risk factors for any DR were shorter axial length (OR 0.81, 95%CI 0.73, 0.89 per mm), more hyperopic refractive error (OR 1.10, 95%CI 1.04, 1.16 per diopter) and lower ocular perfusion pressure (OR 0.96, 95%CI 0.93, 0.98 per mmHg). When stratified by ethnicity, Ocular perfusion pressure was also associated with VTDR and DME. However there was no association between VTDR and DME with Axial length or refractive error were.

Conclusion:

Myopes and those with longer axial length have a lower risk of diabetic retinopathy. However only ocular perfusion pressure was associated with vision threatening diabetic retinopathy and DME. Lower Ocular perfusion pressure may be a good marker for retinal ischemia that predisposes eyes to the more severe forms of diabeti retinopathy.


CONTACT DETAILS

Gavin S Tan, Ching Yu Cheng, Ecosse L Lamoureux, Tien Y Wong
Singapore National Eye Centre
Singapore
Singapore
Email : drgavintan@gmail.com
Cell Phone: +6597361160
Work Phone: +6597126267