Effect of ECG-gating Retinal Photographs on Retinal Vessel Caliber Measurements in Subjects with and without Type 2 Diabetes

• Published in: Current eye research Vol. 46; no. 11; pp. 1742 - 1750
• Main Authors: Lal, Anchal, Dave, Neha, Gibbs, Oliver J., Barry, Michael Anthony (Tony), Sood, Annika, Mitchell, Paul, Thiagalingam, Aravinda
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 02.11.2021
• Subjects: Adult; Cardiovascular Diseases - diagnostic imaging; Cardiovascular Diseases - physiopathology; Cross-Sectional Studies; Diabetes Mellitus, Type 2 - diagnostic imaging; Diabetes Mellitus, Type 2 - physiopathology; Diabetic Retinopathy - diagnostic imaging; Diabetic Retinopathy - physiopathology; Electrocardiography; Electrocardiography - methods; Female; Humans; Male; Middle Aged; Observer Variation; Ophthalmoscopes; Photography - methods; pulsatile flow; Reproducibility of Results; Retinal Artery - diagnostic imaging; Retinal Artery - pathology; Retinal Vein - diagnostic imaging; Retinal Vein - pathology; retinal vessels; Surveys and Questionnaires; type 2 diabetes; Electrocardiography; type 2 diabetes; pulsatile flow; retinal vessels
• ISSN: 0271-3683; 1460-2202; 1460-2202
• DOI: 10.1080/02713683.2021.1927112

Purpose/Aim of this study: Retinal vessel caliber is an independent risk marker of cardiovascular disease risk. However, variable mechanical delays in capturing retinal photographs and cardiac cycle-induced retinal vascular changes have been shown to reduce the accuracy of retinal vessel caliber measurements, but this has only ever been investigated in healthy subjects. This cross-sectional study is the first study to investigate this issue in type 2 diabetes. The aim of this study was to determine whether ECG-gating retinal photographs reduce the variability in retinal arteriolar and venular caliber measurements in controls and type 2 diabetes. Materials and Methods: Fifteen controls and 15 patients with type 2 diabetes were arbitrarily recruited from Westmead Hospital, Sydney, Australia. A mydriatic fundoscope connected to our novel ECG synchronization unit captured 10 ECG-gated (at the QRS) and 10 ungated digital retinal photographs of the left eye in a randomized fashion, blinded to study participants. Two independent reviewers used an in-house semi-automated software to grade single cross-sectional vessel diameters across photographs, between 900 and 1800 microns from the optic disc edge. The coefficient of variation compared caliber variability between retinal arterioles and venules. Results: Our ECG synchronization unit reported the smallest time delay (33.1 ± 48.4 ms) in image capture known in the literature. All 30 participants demonstrated a higher reduction in retinal arteriolar (ungated: 1.02, 95%CI 0.88-1.17% vs ECG-gated: 0.39, 95%CI 0.29-0.49%, p < .0001) than venular (ungated 0.62, 95%CI 0.53-0.73% vs ECG-gated: 0.26, 95%CI 0.19-0.35%, p < .0001) coefficient of variation by ECG-gating photographs. Intra-observer repeatability and inter-observer reproducibility analysis reported high interclass correlation coefficients ranging from 0.80 to 0.86 and 0.80 to 0.93 respectively. Conclusion: ECG-gating photographs at the QRS are recommended for retinal vessel caliber analysis in controls and patients with type 2 diabetes as they refine measurements.