Retinal vessel geometry and oxygen saturation in patients suffering from diabetes mellitus and/ or cardiovascular disease

Abstract

PurposeTo explore the association of retinal vessel parameters such as calibres, reactivity and complexity with vessel oxygen saturation in patients with Diabetes Mellitus and/ or cardiovascular disease.MethodsAll 123 patients underwent a full eye examination including IOP and dilated fundus photography. Retinal oxygen saturation of arteries and veins were measured from dual wavelength retinal photographs (IMEDOS Oxygen module). A‐V saturation was calculated as an estimate of oxygen consumption. Retinal vessel calibre's, tortuosity and fractal dimension were measured using a semi‐automated software to determine CRAE and CRVE (Visualis, IMEDOS and Iflexis, Vito).ResultsPatients mean ranged in age from 32 to 85 years (77 out of the 123 were diabetic). Principal component analysis was performed to establish if the cohort should be split into sub‐groups for further analyses but showed a clear overlap of all patients with no distinct clustering. Subsequently a stepwise forward multiple regression analysis was conducted to explore the relationship between retinal vessel geometry and saturation parameters. Following adjustment for axial length (to account for magnification errors), diastolic blood pressure, retinal vessel fractal dimension and intraocular pressure were significantly associated with A‐V saturation (all p<0.05) meaning a retinal vascular network with a lower fractal dimension (i.e. less vessel density and branching) showed a lower A‐V saturation.ConclusionsThe current study shows that in patients suffering from Diabetes Mellitus and/ or cardiovascular disease, the amount of oxygen used is depending on the complexity of its vascular bed as well as on local and global pressure parameters. These findings could be useful to explore in patients over time or those diabetic retinopathy manifest in different retinal locations.