Factors associated with 1-year visual response following intravitreal bevacizumab treatment for diabetic macular edema: a retrospective single center study

BACKGROUND: To explore the association of clinical characteristics and retinal microstructural features on optical coherence tomography in predicting 1-year visual response following intravitreal bevacizumab injections in eyes with visual impairment from center-involved diabetic macular edema (CI-DME). METHODS: Medical records of patients with visual impairment from CI-DME, who initiated intravitreal bevacizumab injections between Jan 2012 and Dec 2016 and were followed for a minimum of 12 months were retrospectively reviewed. RESULTS: The study included 226 eyes with a mean (SD) baseline visual acuity (VA) of 51.8 (19.1) letters. At week 12, following the three initial treatments, a mean (SD) VA improved to 61.7 (17.8) letters. Visual gain ≥ 10 letters was observed in 109 eyes (48.2%), while a limited early visual gain < 5 letters was noted in 80 eyes (35.4%). At one year, 110 eyes (48.7%) achieved a good VA gain ≥ 10 letters. In addition, eyes with poor baseline VA had a higher proportion of eyes that obtained limited early VA gained at week 12 (< 5 letters) and maintained in this visual response category at moth 12 compared to eyes with better baseline VA (74.1% versus 59.1%). In the multivariable logistic regression, the following factors reduced the probability of 1-year visual gain ≥ 10 letters: elderly (p = 0.040), better baseline vision (p = 0.001), and limited early visual gain < 5 letters at week 12 (p < 0.001). In multivariable linear regression, male (p = 0.010) and eyes with the presence of hyperreflective foci on baseline OCT (p = 0.010) were likely to have higher VA improvement. However, eyes with better baseline VA (p = 0.002), limited early VA gain at week 12 (p < 0.001), and a presence of EZ disruption at week 12 (p = 0.002) were likely to have less VA improvement. CONCLUSIONS: Although bevacizumab is considered as effective management for CI-DME, variability in treatment responses is expected. This study revealed that baseline characteristics and visual responses at week 12 might help predict the long-term treatment response. Eyes with characteristics at risk of limited long-term visual outcome may require attention in optimizing their individual treatment strategies.