Novel Quantitative Retinal Vascular Changes in Diabetes and Retinopathy

Abstract

Purpose: : To examine the relationship of novel quantitative retinal vascular parameters measured from retinal images of persons with diabetes or retinopathy.

Methods: : Retinal photographs from the Singapore Malay Eye Study (SiMES), a population-based, survey of 3,280 (78.7% response) persons aged 40-80 years, were analyzed. Specific retinal vascular parameters (vascular tortuosity, branching angles, fractal dimension, and vascular caliber) were measured quantitatively using a newly developed semi-automated computer-based program. Diabetes mellitus was identified if the random plasma glucose was ≥11.1 mmol/L, participants self reported use of diabetic medication, or had physician-diagnosed diabetes. Retinopathy signs were graded from photographs using the modified Airline House classification system.

Results: : Persons with diabetes (n=594) were more likely to have straighter (less tortuous) arterioles, wider arteriolar caliber and wider venular caliber than those without diabetes (n=2141). Among diabetic subjects, people with retinopathy had wider venular caliber than those without retinopathy (211.2µm vs. 204.9µm, p=0.002), and increasing retinopathy severity level was strongly associated with wider retinal venular caliber (p-trend < 0001). Among non-diabetic subjects, people with retinopathy had more tortuous venules than those without retinopathy (5.17[x10⁴] vs. 4.27[x10⁴], p<0.001), and increasing retinopathy severity level was also associated with more tortuous venules (p-trend = 0.019). In multivariable-adjusted linear regression models, higher HbA1c level was significantly related to straighter arterioles (standardized beta coefficient, sβ=-0.046, p=0.019), wider arteriolar caliber (sβ=0.044, p=0.024) and wider venular caliber (sβ=0.077, p<0.001); higher glucose level was significantly related to smaller fractal dimension (sβ=-0.040, p=0.038), wider arteriolar caliber (sβ=0.077, p<0.001) and wider venular caliber (sβ = 0.076, p<0.001).

Conclusions: : We demonstrated that retinal vascular changes, quantitatively measured from digital retinal images, were associated with diabetes or with retinopathy in persons with or without diabetes. Our findings support the concept that subtle alterations in retinal vascular architecture, seen in the retina, may reflect both early diabetic and non-diabetic related systemic microvascular damage.

Keywords: diabetic retinopathy • imaging/image analysis: clinical • retina