Changes in central retinal and choroidal OCT/OCTA parameters following intravitreal bevacizumab injection in diabetic macular edema

Abstract

Background To evaluate changes in central macular thickness (CMT), subfoveal choroidal thickness (SFCT), and foveal vessel density (VD) in deep and superficial capillary plexuses (DCP and SCP) 30 days after intravitreal bevacizumab (IVB) injection in eyes with diabetic macular edema (DME). Methods A prospective observational study on 25 eyes of 25 patients who were candidates of intravitreal anti-VEGF injection for the treatment of DME was conducted. After conducting a comprehensive ophthalmic examination, using optical coherence tomography angiography (OCTA) and enhanced depth imaging OCT, we measured CMT, SFCT, and foveal VD in DCP and SCP. In addition, a blood sample was drawn from every patient to determine baseline hemoglobin A1c levels. One month after a single IVB injection, all the parameters were reassessed. Results Mean age of the included patients was 59.56 ± 9.74 years. One month following bevacizumab injection, mean CMT, SFCT, VD in superficial capillary plexus, and VD in deep capillary plexus layer significantly (P < 0.05) decreased by 10.03% ± 5.53%, 8.18% ± 3.39%, 3.06% ± 6.98%, 3.65% ± 6.41%, respectively. Best corrected visual acuity (BCVA; LogMAR) was also improved significantly. Patients with HbA1c level ≤ 7 at baseline showed a larger decrease in CMT (P = 0.02) with no significant difference in other parameters. The decrease in LogMAR BCVA after treatment showed a negative correlation with pre-treatment SFCT and a positive correlation with the decrease in foveal VD in SCP (rho = -0.42, P = 0.04, and rho = 0.44, P = 0.03, respectively). Spearman correlation analysis showed no significant association between the changes in CMT, SFCT, and VD in superficial or deep capillary plexuses. Patients with better anatomical response to the treatment (CMT reduction ≥ 10%) had significantly lower SFCT and higher CMT values at baseline. Conclusions Significant functional and anatomical improvements were evident one month after IVB injection in patients with DME. Better glycemic control could result in a significantly larger reduction in the CMT of eyes with DME. Anatomical improvements were not correlated with changes in other assessed variables. Thinner SFCT at baseline could be attributed to better functional and anatomical response in these patients.