Abstract:

Objective To investigate the effect of intravitreal ranibizumab (IVR) injection on the restoration of outer retinal structural integrity in diabetic macular edema (DME). Methods In this retrospective study, totally 24 DME patients (28 eyes) were treated with intravitreal injections of 0.05ml ranibizumab with average time of follow-up was 8.21±1.56 months. Best corrected vision acuity (BCVA) of pre- and post-treatment was recorded in detail, which calibrated a logarithm of the minimal angle of resolution (logMAR) visual acuity chart in statistical analysis. Spectral domain optical coherence tomography (SD-OCT) was performed pre- and post-treatment. The characteristics of macular structural were statistically analyzed, including central macular thickness (CMT), the continuity of external limiting membrane (ELM) and ellipsoid zone (EZ).Results Mean logMAR VA of 28 eyes decreased after IVR therapy from 1.38±0.21 at baseline to 0.39±0.08 at 6 months after the first injection (P<0.05). Similarly, CMT reduced from (416.36±23.10)μm at baseline to (231.15±38.26) μm at 6 months after the first injection (P<0.05). Global ELM disruption reduced from 78.6% pre-treatment to 10.7% at 6 months after the first injection; likewise global EZ disruption reduced from 71.4% to 14.3%.There was a strong correlation between BCVA and CMT (r=0.356, P<0.01), the statuses of ELM (r=0.589, P<0.01) and EZ (r=0.626, P<0.01).Conclusion Anti-vascular endothelial growth factor (VEGF) therapy can restore the integrity of outer retinal structure (ELM, EZ) in DME patients, thus improving vision. ELM restoration preceds EZ restoration.

Key words: diabetes mellitus, macular edema, central macular thickness, external limiting membrane, ellipsoid zone, optical coherence tomography