Structures affecting recovery of macular function in patients with age-related macular degeneration after intravitreal ranibizumab

To determine the retinal structures affecting the recovery of macular function in patients with exudative age-related macular degeneration (AMD) treated with intravitreal ranibizumab (IVR).

Thirty eyes of 30 patients with exudative AMD who were treated with IVR at monthly intervals for 3 months were studied. Focal macular electroretinograms (fmERGs) and spectral-domain optical coherence tomography (SD-OCT) were performed before and 3 months after beginning the IVR injections. The fmERGs were elicited by a 15° white stimulus spot centered on the fovea. The thickness of different retinal layers, presence of a serous retinal detachment (SRD), and presence of a pigment epithelial detachment (PED) at the fovea was determined in the SD-OCT images. Measurements were made of the inner, middle, and outer layers of the retina and also of the SRD and PED in the horizontal and vertical meridians at 1.2 mm from the fovea (parafoveal regions). The significance of the correlations between these structural parameters and the a-wave amplitude of the fmERG was determined.

There was no significant correlation between the structural parameters of the fovea and the a-wave amplitude. In the parafoveal regions, the thickness of the outer retinal layer was significantly correlated with an increase of the a-wave amplitude (R = 0.56, P = 0.001). In addition, the SRD thickness was negatively and significantly correlated with the a-wave amplitude (R = −0.54, P = 0.002). The change in the parafoveal SRD thickness after IVRs was the only independent determinant of recovery of the a-wave amplitude after the treatments (P < 0.05).

The macular function measured by the fmERGs was determined by the parafoveal outer layer and SRD thickness in patients with exudative AMD. Of these, changes in the SRD thickness by IVRs most strongly affected the recovery of macular function.