Vascular dynamics in diabetic retinopathy: A systematic review and meta-analysis of ophthalmic Doppler indices in diabetic and non-diabetic populations.

BackgroundOphthalmic Doppler ultrasonography is a non-invasive technique for evaluating hemodynamic changes in diabetic patients. This meta-analysis assessed ophthalmic Doppler indices in diabetic patients with and without retinopathy compared to non-diabetic controls.MethodsWe searched Scopus, PubMed, ScienceDirect, and SpringerLink for studies investigating Doppler ultrasound parameters in diabetic retinopathy (DR). Pooled mean differences with 95% confidence intervals were estimated using random-effects models for peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI). Study quality was assessed using QUADAS-2 and QUADAS-C.ResultsFourteen studies (1,217 patients) were included. People with diabetes without retinopathy showed significantly elevated RI (MD 0.08, P=0.004) and PI (MD 0.30, P<0.0001) in the ophthalmic artery versus controls. The central retinal artery showed marked reductions in PSV and EDV (P<0.00001) and increased RI (P=0.001) in established DR. RI was also elevated in the posterior ciliary artery across all diabetic stages. Diagnostic accuracy analyses yielded pooled RI sensitivity of 0.73-1.00 and PI sensitivity of 0.79-1.00.ConclusionOphthalmic artery Doppler indices, particularly RI and PI, were associated with DR severity that may represent possible additional markers of microvascular dysfunction. However, these findings require confirmation in well-designed prospective studies before RI and PI can be considered established early markers.