A Cross-Sectional Study of Various Imaging and Biochemical Biomarkers in Patients with Diabetic Macular Edema in Different Stages of Diabetic Retinopathy

Prithvi Naveen, Vijaya Sahu, Madhumallika Pathak Department of Ophthalmology, AIIMS Raipur, Raipur, Chhattisgarh, IndiaCorrespondence: Vijaya Sahu, 2D, Block 5, Singapore City, Kota, Raipur, 492099, India, Tel +91 9752679556, Email drvijayasahu77@gmail.comPurpose: To compare which imaging and biochemical biomarkers are associated with different stages of diabetic retinopathy (DR) in type 2 diabetes mellitus patients with diabetic macular edema (DME).Patients and Methods: It was a cross-sectional, observational study that included 100 patients of DME with different stages of DR. Patients were divided into two groups: Group A – DME with non-proliferative diabetic retinopathy (NPDR) and Group B - DME with proliferative diabetic retinopathy (PDR). Group A was further subdivided into three subgroups: A (1) – DME with mild NPDR, A (2) – DME with moderate NPDR, and A (3) – DME with severe NPDR. The primary outcome measure was the association of imaging and biochemical biomarkers with different stages of DR in patients with DME.Results: Out of 100 patients, Group A (1) had 1, Group A (2) 44, Group A (3) 29, and group: B had 29 patients. As Group A (1) had only one patient, we did not include it in the calculation. The overall mean age of the study population was 54.84+9.87 years, with a male preponderance (76%). The HbA1c levels, serum triglyceride level, serum cholesterol level, and microalbuminuria level showed no significant association with different stages of DR (P> 0.05). Still, we found high serum urea levels (p=0.027) in Group B patients. The optical coherence tomography (OCT)-based imaging biomarkers – central subfield thickness (CST), cystoid macular edema (CME), subretinal fluid (SRF), and hyperreflective foci (HRF) – showed no significant association with various stages of DR. The presence of diffuse retinal thickness (DRT) (p=0.04) and the epiretinal membrane (ERM) (p=0.04) showed significant association with Group B patients.Conclusion: The essential biochemical biomarkers such as serum urea levels and DRT and ERM may be considered an important imaging biomarker for the advanced stage of DR.Keywords: imaging biomarkers, biochemical biomarkers, central subfield thickness, diffuse retinal thickness, serum urea level