Purpose  This study examined the association of retinal vacular geometric measurements including tortuosity, branching angle and fractal dimension, with glaucoma.
Methods  In the population-based cross-sectional Singapore Malay Eye Study, 2929 participants of Asian Malay ethnicity aged 40-80 years had dilated digital retinal photographs taken of both eyes. Retinal vascular tortuosity, branching angle and fractal dimension were measured using a computer-based technique following a standardized protocol. Glaucoma was diagnosed based on the International Society of Geographic and Epidemiological Ophthalmology classification and included people with glaucomatous optic neuropathy and compatible visual field loss.
Results  There were 123 (4.2%) participants with glaucoma. After adjustment for age, sex, diabetes, hypertension, axial length, smoking status and IOP, decreased retinal arteriolar and venular tortuosity (ie straighter vessels) was associated with increased odds of any glaucoma (odds ratio, OR 5.37 and 6.71 per SD decrease for arteriolar and venular tortuosity, respectively), POAG (OR 6.34 and 6.69), NTG (OR 5.92 and 7.97), and VCDR≥0.6 (OR 1.27 and 1.73). Smaller venular branching angle was associated with increase odds of any glaucoma (OR 1.24), POAG (OR 1.32) and NTG (OR 1.40). Smaller fractal dimention was associated with any glaucoma (OR 1.42), POAG (OR 1.29) and NTG (OR 1.36).
Conclusions  These findings support associations between altered retinal vascular geometry and glaucomatous optic neuropathy, independent of intraocular pressure. This study adds to the evidence of vascular correlates of glaucoma.