The Correlation of Optical Coherence Tomography Angiography Parameters With Serum Vascular Endothelial Growth...

Background and objective Vascular endothelial growth factor-A (VEGF-A) plays an important role in the development of diabetic macular edema (DME). In this study, we aimed to correlate optical coherence tomography angiography (OCTA) parameters with serum VEGF-A levels in DME. Methodology We conducted a prospective study, which examined 44 eyes of 32 DME patients (mean age: 56.0 ±9.1 years) for visual acuity (VA), defective colour vision (CV), and contrast sensitivity (CS). The OCT was done for central foveal thickness (CFT), sub-foveal choroidal thickness (SFCT), neurosensory detachment (NSD), epiretinal membrane (ERM), and disorganized retinal inner layers (DRIL). The OCTA was used to study the foveal avascular zone (FAZ) in superficial capillary plexus (SCP) and vessel density (VD) in six retino-choroidal layers, including SCP, deep capillary plexus (DCP), outer retina (OR), outer retinal chorio-capillaries (ORCC), chorio-capillaries (CC), and choroid. The serum VEGF-A levels were measured using an enzyme-linked immunosorbent assay (ELISA) kit. The eyes were treated with a single intravitreal injection of 0.3 mg/0.05 ml ranibizumab biosimilar (RbB). The subjects were re-examined after a short period of one month for visual, OCT, and OCTA parameters and serum VEGF-A levels. A correlation between OCTA parameters and serum VEGF-A was done on both occasions. Results At baseline, the logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) was 0.82 ±0.13, CFT 464.60 ±173.06 microns, SFCT 238.02 ±42.88 microns, and the serum VEGF-A level was 487.94 [interquartile range (IQR): 305 to 775.52] pg/ml. There was a positive correlation of serum VEGF-A level with LogMAR BCVA (r=0.15), CFT (Rho=0.02) and SFCT (Rho=0.14), while there was a negative correlation with FAZ area (Rho=-0.20), perimeter (Rho=-0.19) and VD of SCP (Rho=-0.22), DCP (Rho=-0.02), OR (Rho=-0.10), ORCC (Rho=-0.12), CC (Rho=-0.10) and choroid (Rho=-0.17). After a short follow-up of one month following intravitreal injection, LogMAR BCVA was 0.53 ±0.22, CFT 350.07 ±153.02 microns, SFCT 232.40 ±44.30 microns, and the serum VEGF-A level measured 404.02 (IQR 204.61 to 750.87) pg/ml. There was a positive correlation of serum VEGF-A level with LogMAR BCVA (r=0.48), CFT (Rho=0.19), and SFCT (Rho=0.11), while there was a negative correlation of serum VEGF-A levels with FAZ area (Rho=-0.01), perimeter (Rho=-0.06), and VD of SCP (Rho=-0.22), DCP (Rho=-0.13), OR (Rho=-0.10), ORCC (Rho=-0.25), CC (Rho=-0.18), and choroid (Rho=-0.29). The correlation coefficient values indicated that all observed correlations were weak. Conclusion In our study, the BCVA decreased while CFT and SFCT increased, along with an increase in serum VEGF-A levels. The higher serum VEGF-A was related to smaller FAZ and lower retino-choroidal VD. The observed weak correlation of ocular, OCT, and OCTA features with serum VEGF-A levels may limit the predictive value and clinical utility of these biomarkers in the management of DME.