Risk Factors of Internal Carotid Artery Stenosis in Patients with Proliferative Diabetic Retinopathy: An Analysis Using Optical Coherence Tomography and Optical Coherence Tomography Angiography

Abstract

Purpose The study examines the correlation between internal carotid artery(ICA) stenosis and retinal parameters in patients with proliferative diabetic retinopathy(PDR). The objective is to determine potential links between the degree of ICA stenosis and various retinal parameters, providing insight into associated risk factors. Methods We conducted a retrospective analysis of 68 patients (136 eyes) diagnosed with bilateral proliferative diabetic retinopathy between January 1, 2017 and December 31, 2021. We assessed the presence and severity of carotid artery stenosis using neck CTA and CDUS, and classified the degree of ICA stenosis into a four-grade system based on the North American Symptomatic Carotid Endarterectomy Trial(NASCET) criteria by CTA and a grayscale panel determined by CDUS. To simplify the analysis, we categorized the degree of stenosis into two groups: group 1 corresponds to stenosis at the normal level, while group 2 includes stenosis at or above the mild level. We then performed OCT and OCTA to examine SFCT, RNFL thickness, GCIPL thickness, VD, and FAZ area in each group. Statistical analysis was performed to determine the correlation between the degree of carotid artery stenosis and various retinal parameters. Specifically, we compared the retinal parameters between group 1 and group 2 using appropriate statistical tests. The p-value of less than 0.05 was considered statistically significant. Results The mean age of this study patients were 62.55 years. Among them, significant differences were observed between group 1 and 2 in terms of total VD (13.73 ± 3.21, 11.53 ± 3.37, respectively; p = 0.003), FAZ area (0.53 ± 0.62, 0.56 ± 0.84, respectively; p = 0.002), total RNFL thickness (97.87 ± 5.542, 95.04 ± 4.10, respectively; p = 0.013) and temporal RNFL thickness (82.46 ± 27.74, 71.75 ± 20.18, respectively; p = 0.019). RNFL thickness showed statistically significant thinning in group 2 with severe degree of ICA stenosis, decreasing to 71.75 ± 20.19 µm (p = 0.019). Apart from age, there were notable distinctions observed in hyperlipidemia and total cholesterol levels, as well as in IOP measurements. Specifically, the IOP values exhibited significant variations (61.5 ± 10.58 vs. 66.7 ± 7.52, p = 0.003), (15.20% vs. 50%, p = 0.002), (224.97 ± 151.64 vs. 164.41 ± 115.62, p = 0.019), (15.78 ± 7.08 vs. 14.2 ± 2.62, p = 0.042). In contrast, no significant differences were found between group 1 and group 2 in terms of SFCT, central VD, average GCIPL and thickness of the superior, nasal, and inferior RNFL. Conclusions The study findings highlight retinal changes, such as an increased FAZ area, decreased total VD, and a total and thinner temporal RNFL, which suggest the need for carotid artery evaluation in patients. These findings have important clinical implications for the need for carotid work up in pateints with PDR.