C-Reactive Protein and Retinal Vascular Caliber: The Singapore Malay Eye Study

Abstract

Purpose: : To examine the relationship between C-reactive protein (CRP), a systemic marker of inflammation, and retinal vascular caliber.

Methods: : The Singapore Malay Eye Study is a population-based cross-sectional survey that included 3280 (78.7% response) persons aged 40-80 years. The study population was selected using an age-stratified random sampling procedure of Malay adults living in the south-western part of Singapore. Retinal vascular caliber was measured from digital retinal photographs using a validated standardized protocol. A venous blood sample was taken from all participants and assessed for serum CRP as well as serum lipids, glucose and glycosylated haemoglobin (HbA1c). CRP had a skewed distribution and therefore logCRP with a normal distribution was used in some statistical models.

Results: : There were 2867 participants had both serum CRP and retinal vascular calibre data available. The mean CRP was 4.1 ± 8.12mg/dL (SD), mean retinal arteriolar caliber was 139.5 ±15.7 µm and the mean retinal venular caliber was 219.3 ±22.2 µm. Higher CRP levels were associated with higher body mass index, diabetes, hypertension, cigarette smoking, and higher levels of systolic and diastolic blood pressure, serum total and LDL-cholesterol, serum triglyceride, blood glucose, glycosylated haemoglobin and lower levels of HDL-cholesterol. LogCRP levels was correlated with larger venular caliber (Pearson’s correlation coefficient 0.134, P<0.001). In models adjusted for age, gender, HbA1c, BMI, HDL cholesterol, education , hypertension and current smoking status and arteriolar caliber, higher CRP levels were associated with larger venular caliber (223.0 versus 217.7µm, comparing 4^th to 1^st CRP quartiles, p<0.001). CRP was not associated with arteriolar caliber (p=0.103).

Conclusions: : Retinal venular caliber is associated with CRP independent of other factors. These data suggest that measurement of retinal venular caliber may allow investigation of retinal and systemic diseases associated with inflammation.

Keywords: retina • inflammation