Retinal Vascular Geometry in Hypertension: cSLO-Based Method

INTRODUCTION: We aim to introduce a method using confocal scanning laser ophthalmoscopy (cSLO) images for measuring retinal vascular geometry, including vessel branch angle (BA), vessel diameter, vessel tortuosity, and fractal dimension (D(f)), and to elucidate the relationship between hypertension and these metrics. METHODS: A total of 119 participants (119 eyes) were enrolled, among which 72 were normotensive and 47 were hypertensive. Infrared cSLO images were extracted from the circular scan around the optics disc using a commercial cSLO + optical coherence tomography instrument. Preprocessed cSLO images were further analyzed using the appropriate tool/macro/plugin of ImageJ. RESULTS: Intraclass correlation coefficients of selected methods used for conducting the cSLO-based geometric analyses were all higher than 0.80. Arterial/arteriolar BA, arteriolar vessel diameter, and total D(f) in normotensive subjects were 85.80 ± 7.79°, 116.80 ± 12.58 μm, and 1.430 ± 0.037, respectively, significantly higher than those of hypertensive subjects (82.13 ± 10.83°, 108.2 ± 11.12 μm, and 1.361 ± 0.044, all P < 0.05). The aforementioned metrics remained negatively correlated with hypertension even after adjusting for age alone or age and gender (P < 0.05). However, the difference between arteriolar tortuosity and all studied venous/venular geometric parameters in both subjects was insignificant (all P > 0.05). CONCLUSION: Proposed cSLO-based methods for assessing various vascular geometric parameters were highly repeatable and reproducible. Arterial/arteriolar BA, arteriolar vessel diameter, and total D(f) were retinal vascular parameters significantly correlated with hypertension in a negative manner.