Diabetes, Hyperglycemia, and Central Corneal Thickness: The Singapore Malay Eye Study
Received 5 April 2007; received in revised form 27 July 2007; accepted 10 August 2007. published online 26 October 2007.
Purpose
To examine the relationship of diabetes and hyperglycemia with central corneal thickness (CCT) in Malay adults in Singapore.
Design
Population-based cross-sectional study.
Participants
Three thousand two hundred eighty Malay adults ages 40–80 years living in Singapore.
Methods
The study population was selected using an age-stratified random sampling procedure of Malay 40- to 80-year-olds living in the southwestern part of Singapore. Participants had a standardized interview, examination, and ocular imaging at a centralized study clinic. Central corneal thickness was measured with an ultrasound pachymeter, and nonfasting serum glucose and glycosylated hemoglobin (Hb A1C) was obtained from all participants. Diabetes was defined as having nonfasting glucose levels of ≥200 mg/dl (11.1 mmol/l), a self-report of diabetic medication use, or physician diagnosis of diabetes.
Main Outcome Measures
Central corneal thickness.
Results
Of the 3280 (78.7% response) participants, data on CCT were available on 3239 right eyes. Central corneal thickness was normally distributed, with a mean of 541.2 μm. There were 748 persons with diabetes (23.0%). After controlling for age and gender, central corneas were significantly thicker in persons with diabetes than in those without diabetes (547.2 μm vs. 539.3 μm, P<0.001) and, in the total population, with higher serum glucose (539.6, 540.2, 541.3, and 544.4, comparing increasing glucose quartiles; P = 0.023) and higher Hb A1C (537.8, 541.0, 541.4, and 545.5, comparing increasing Hb A1C quartiles; P<0.001) levels. In multiple linear regression models adjusting for age, intraocular pressure (IOP), body mass index, and axial length, persons with diabetes had, on average, central corneas 6.50 μm thicker than those of persons without diabetes.
Conclusions
This population-based study among Malays showed that diabetes and hyperglycemia are associated with thicker central corneas, independent of age and IOP levels. These findings may have implications for understanding the relationship between diabetes and glaucoma.
Available online: October 26, 2007.
1Singapore National Eye Centre & Singapore Eye Research Institute, Singapore.
2Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
3Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia.
4Department of Community, Occupational, and Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
6Institute of Ophthalmology, University College London, London, United Kingdom.
Correspondence to A/Prof Tin Aung, PhD, Glaucoma Department, Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751.
Manuscript no. 2007-472.
Funded by the National Medical Research Council, Singapore (grant no. 0796/2003), and Biomedical Research Council, Singapore (grant no. 501/1/25-5), with support from the Singapore Prospective Study Program and Singapore Tissue Network, A*STAR.
ABSTRACT