Symmetry in early response to intravitreal ranibizumab in bilateral diabetic macular oedema

To study the symmetry in response to bilateral diabetic macular oedema (DME) treated with bilateral intravitreal injections of ranibizumab (IVR).

The charts of 36 eyes of 18 patients treated with a loading dose of three monthly IVR in both eyes were retrospectively reviewed. Favourable anatomical response was defined as a decrease by more than 10% in baseline central macular thickness (CMT), and favourable functional response was defined as an increase in visual acuity (VA) ≥5 letters. A symmetric response was defined as a similar anatomical and/or functional response in the first (FE) and second (SE) treated eyes.

The VA improved significantly after ranibizumab treatment in both eyes (p < 0.01). A statistically significant positive correlation was found for the functional response to ranibizumab between the FE and the SE (R(2)  = 0.26, p = 0.03). The mean CMT decreased significantly in both eyes (p < 0.01). A strong positive correlation was observed between the anatomical response to ranibizumab in the FE and the SE (R(2)  = 0.37, p = 0.01). Symmetric favourable anatomical and functional responses were observed in 13 patients (72%). In two additional patients, an asymmetric functional response was observed despite a decrease in retinal thickness in both eyes.

Symmetric anatomical and functional responses were observed in 72% of patients with DME after three initial IVR in each eye. This finding could be of clinical interest in the decision to treat the fellow eye, in a disease where a bilateral involvement is frequent.