[Unilateral Ranibizumab Treatment and Reduction of Macular Edema in the Contralateral Eye. Medication Effect or...

During unilateral treatment with ranibizumab, a reduction in the retinal thickness in the non-treated eye is occasionally observed. This may be due to the natural progression of the condition. It could also be the consequence of systemic absorption of intravitreal injections, leading to effects in the contralateral eye.

We describe 40 patients with either exsudative age-related macular degeneration (AMD) or diabetic macular oedema (DME). During treatment with ranibizumab, a reduction in retinal thickness in the contralateral eye was observed in this group (observation group). Another 40 AMD or diabetes patients under treatment with ranibizumab were selected as control group. These patients showed retinal swelling in the contralateral eye, which remained stable or increased.

In the observation group, 58 % of the patients had a DME and 42 % had an AMD; in the control group, 25 % of the patients had a DME and 75 % of the patients had an AMD (p = 0.003). Retinal thickness before injection was 519 ± 126 µm in the observation group and 432 ± 87 µm in the control group (p = 0.003). Retinal thickness in the contralateral eye was then 511 ± 162 µm in the observation group and 436 ± 149 µm in the control group (p = 0.036). The reduction in retinal thickness in the injected eye was 214 ± 144 µm in the observation group and 150 ± 89 µm in the control group (p = 0.06).

In the group of patients that showed reduction in retinal thickness under ranibizumab in the contralateral eye, there were more diabetes patients than in the comparable control group. Even before injection, these patients showed higher retinal thickness in both eyes than did those in the control group. Further prospective studies would be required to confirm a possible causal connection between ranibizumab injection and reduction in DME in the contralateral eye.