REFERENCE VALUES OF RETINAL MICROCIRCULATION PARAMETERS IN A WHITE POPULATION RANDOM SAMPLE. CZECH POST-MONICA STUDY

Abstract

Objective: Retinal microcirculation reflects retinal perfusion abnormalities and retinal arterial structural changes at relatively early stages of various cardiovascular diseases. Our objective was to establish reference values for major functional and structural parameters of retinal microcirculation in a randomly selected urban population sample.Design and method: A total of 398 randomly selected individuals from an urban population aged 25 to 65 years, resident in Pilsen, Czech Republic, were screened for major cardiovascular risk factors. Retinal microcirculation was assessed using scanning laser Doppler flowmetry (SLDF), with data evaluable in 345 patients. Of this number, complete data were available for 257 individuals free from manifest cardiovascular disease, diabetes and drug treatment for hypertension and/or dyslipidemia who made up the reference value population. Results: Retinal capillary blood flow (RCF) increased significantly with age whereas vessel and luminal diameters decreased. No sex differences in retinal microcirculation parameters were found. Reference values by age were established (see Table). A comparison between the reference value population and the diseased population (n = 88) derived from the same population sample found significant differences in age, BMI, BP, HbA1c, pulse wave velocity and prevalence of dyslipidemia, with the latter population consistently showing less favorable values. When comparing retinal parameters, after adj. for age, the only differences were found in vessel (reference value population: 103.5 ± 0.8 vs. diseased population: 107.0 ± 1.5 μm; p = 0.05) and luminal diameters (reference value population: 77.1 ± 0.5 vs. diseased population: 80.1 ± 0.9 μm; p = 0.007), with no differences in wall thickness or wall-to-lumen ratio, thus confirming that, at the population level, the first structural changes in retinal microcirculation are changes in lumen diameters. Conclusions: This is the first study providing reference values of retinal microcirculation parameters in a random white population sample. Our results show that, at the population level, the first structural changes in retinal microcirculation are those in lumen diameters.