Predicting 1-month response of macular edema to intravitreal bevacizumab from 1-hour response.

OBJECTIVE: To evaluate the clinical significance of the change in central macular thickness (CMT) measured 1 h after intravitreal bevacizumab injection (IVB) for macular edema (ME) secondary to diabetic retinopathy or retinal vein occlusion (RVO).

DESIGN: Retrospective case series.

PARTICIPANTS: Thirty eyes with ME treated with IVB.

METHODS: A single IVB (1.25 mg/0.5 mL) was administered in 14 eyes with diabetic macular edema (DME) and 16 eyes with ME secondary to RVO. CMT was measured using spectral-domain optical coherence tomography before injection and again 1 hour and 1 month after injection.

RESULTS: Statistically significant CMT reduction was observed at both time points. CMT declined from 542.3 ± 127.7 µm at baseline to 516.9 ± 123.4 µm 1 hour after injection (p < 0.001) and to 345.5 ± 110.0 µm at 1 month after injection (p < 0.001). The reduction in CMT 1 hour after injection was significantly correlated with the reduction in CMT observed at 1 month after injection, with respect to both absolute (r = 0.515, p = 0.004) and relative changes (r = 0.454, p = 0.012). The 15 eyes that had larger 1-hour CMT reductions also showed larger 1-month CMT reductions (242.9 ± 133.8 µm and 43.4% ± 16.5%) when compared with 15 eyes with smaller 1-hour CMT reductions (148 ± 130.6 µm and 25.0% ± 18.3%). This trend was the same for absolute and relative changes (p = 0.037 and 0.008).

CONCLUSIONS: The 1-month response of ME to IVB can be predicted by checking CMT 1 hour after injection.