Evaluation of retrobulbar circulation in diabetic patients using color Doppler imaging

Background: Diabetic retinopathy (DR) is a microvasculature disorder of the retina. Color Doppler imaging is a new method that allows simultaneous two-dimensional anatomical and Doppler evaluation of hemodynamic characteristics of the retinal artery. Aim: The aim of the study is to compare retrobulbar vessel Doppler indices in DR and diabetic with no retinopathy (DNR) using color Doppler sonography. Materials and Methods: A time-limited, hospital-based study was conducted at a tertiary care hospital in Indore, Madhya Pradesh. The study included DR and DNR who were referred from the ophthalmology outpatient department to the radiology. Ophthalmologists performed baseline fundoscopy to categorize patients into different levels of retinopathy severity based on the International disease severity scale proposed by Wilkinson, which has five levels ranging from none to proliferative DR, indicating the risk of progression. Results: In the DR group, 26 (74.25%) patients had hemoglobin A1c (HbA1c) levels ranging from 7 to 7.9 and in the DNR group, 9 (26%) patients had HbA1c levels ranging from 6 to 6.9. Among 35 patients with DR, 25 (71%) patients and 7 (20%) had mild DR and moderate DR, respectively, and only 3 (8%) patients belonged to severe DR. The median resistive index (RI) of the ophthalmic artery in DR and DNR groups was 0.83 and 0.73, respectively. The median RI of the central retinal artery in DR and the DNR group was 0.8 cm/s and 0.6 cm/s, respectively. In the posterior ciliary artery, the median RI was higher in the DR group, i.e. 0.78, compared to the DNR group, i.e. 0.63. As RI depicted increased vascular resistance, it was higher in the DR group than in the DNR group. A weak positive correlation was found between HbA1c and peak systolic velocity, end-diastolic volume, and RI of all three arteries (ophthalmic artery, central retinal artery, and posterior ciliary artery) as inferred from the Spearman's rank correlation coefficient among both groups. Conclusion: Color Doppler ultrasonography can be used to assess these microvascular changes and provides the association between the altered ocular blood flow and the severity of retinopathy. It helps us to predict even before DR appearance, enabling early diagnosis of DR and early intervention