Purpose: To determine the pattern of electroretinographic change after an intravitreal ranibizumab (Lucentis(®)) injection for the treatment of choroidal neovascular membrane (CNVM).
Patients and methods: A prospective interventional case series of patients treated by intravitreal ranibizumab injection. Best corrected visual acuity, optical coherence tomography (OCT), and multifocal electroretinography (mfERG) were assessed prior to treatment, and 2 weeks, 1 and 3 months after treatment. Primary outcome was the functional change in amplitude and implicit time by mfERG and secondary outcome was the structural change in macular thickness by optical coherence tomography (OCT).
Results: Twenty-six eyes from 25 consecutive patients were enrolled. At 3 months after treatment, the mean visual acuity (VA) improved from 1.06 to 0.84 logMAR (P = 0.034) and the mean macular thickness decreased from 389.7 to 264.4 microns (P = 0.003). The mean implicit time of the central zone showed an improvement at 3 months after treatment when compared with the response at baseline (P = 0.024) and at 1 month (P = 0.013) but the mean amplitude showed no significant change. In subgroup analysis, the eyes with initial visual acuity (VA) ≥ 20/200 had a significant improvement in mean implicit time of the peripheral zone at 2 weeks after treatment (P = 0.028). The OCT revealed a significant decrease (P < 0.003) in macular thickness at 1 and 3 months postoperatively.
Conclusion: The mean implicit time of the central zone improved significantly at 3 months after treatment, whereas the mean amplitude showed no significant change. The macular thickness decreased significantly after the treatment, while VA improved to a lesser extent.
Keywords: choroidal neovascular membrane (CNVM); intravitreal injection; multifocal electroretinography (mfERG); optical coherence tomography (OCT); ranibizumab.