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Tomoharu Nishimura, Shigeki Machida; Macular Function in Macular Edema Associated with Branch Retinal Vein Occlusion Treated with Intravitreal Ranibizumab. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4090.
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Randomized clinical trials have shown that intravitreal ranibizumab (IVR) brought about improvement in the visual acuity and macular morphology in patients with macular edema associated with branch vein occlusion (BRVOME). BRVO involves wide area of the retina including non-occluded side of the macula by blood or edema spreading from the occluded side, suggesting that the macular function on the non-occluded side would be affected. The aim of this study is to evaluate treatment efficacy of IVRs in the macular function on occluded and non-occluded sides separately by using the focal macular electroretinogram (fmERG).
We studied 13 eyes of 13 patients with BRVOME. All patients were treated with IVRs at monthly intervals for three consecutive months. Additional treatment was done according to the pro re nata (PRN) regimen. The best corrected visual acuity (BCVA), spectral-domain optical coherence tomography and fmERG were recorded at the pre-treatment (baseline) and at 3, 6, and 12 months after beginning the treatment. The fmERG was recorded with circular, superior and inferior hemi-circular stimulation spots with a diameter of 15°. The amplitudes of a- and b-waves, photopic negative response (PhNR), and sums of the oscillatory potentials (ΣOPs) were measured in addition to the implicit time of a- and b-waves.
The BCVA significantly improved at 3 months (P<0.05), and was maintained until 12 months. The foveal thickness significantly decreased at 3 months (P<0.005) with subsequent worsening at 12 months (P<0.05). In the fmERG, on non-occluded side, while the amplitudes and implicit time of a- and b-waves remained unchanged, the PhNR and ΣOPs amplitudes significantly increased at 3 months compared to the baseline (PhNR: P <0.005, ΣOPs: P< 0.005) with subsidence of the thickened retina, which was maintained until 12 months. On the occluded side, although the b-wave, PhNR and ΣOPs amplitudes improved at 3 months compared to the baseline, they declined subsequently during the PRN period.
IVRs provide improvement in the macular function not only on the occluded side but also on the non-occluded side of the macula. However, the consequent deterioration of the macular function on the occluded side during the PRN period suggests that PRN is not suitable treatment regimen for maintaining the macular function in BRVOME.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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