One-year-results of Structure-function Correlation in Patients with Age-related Macular Degeneration Treated with Intravitreal Ranibizumab

Abstract

 

Purpose

 

Previously, we have reported that the macular function assessed by the focal macular electroretinogram (fmERG) was correlated with thickness of the parafoveal outer layer and the serous retinal detachment (SRD) in patients with age-related degeneration (AMD) (Nishimura et al. 2014). In the present study, we shall investigate correlation between optical coherence tomographic (OCT) findings and macular function at 12 months after beginning IVR in AMD patients.

 

Methods

 

We studied 28 eyes of 28 patients with exudative AMD treated with IVR at monthly intervals for initial three months. Additional IVR was given according to the OCT-guided variable-dosing regimen used in the PrONTO study. The fmERG and OCT were performed 3, 6, 9 and 12 months postoperatively. The fmERGs were elicited by a 15° white stimulus spot centered on the fovea. The thickness of the inner, middle and outer layer of the retina and also of the SRD and pigment epithelial detachment (PED) in the horizontal and vertical meridians at 1.2 mm from the fovea (parafoveal region) was measured in the OCT images. The significance of the correlations between these structural parameters and the b-wave amplitude of the fmERG was determined. The difference between the maximum and minimum values of these structural parameters during 9 months from the 3^rd to 12^th month designated as changes of the structures during the PRN treatment period.

 

Results

 

The b-wave amplitude of the fmERG at the 12^th month was significantly correlated with thickness of an outer layer, SRD and PED thickness (outer layer: R=0.62, P=0.001, SRD: R=-0.49, P=0.02, PED: R=-0.54, P=0.003). The b-wave amplitude at the 12th month was also significantly correlated with changes of the thickness of the outer layer, SRD and PED during the PRN treatment period (outer layer: R =-0.56, P=0.002; SRD: R=-0.49, P=0.03, PED: R=-0.55, P=0.002).

 

Conclusions

 

The parafoveal outer retinal and subretinal structures at the 12^th month were correlated with the macular function measured by the fmERG. Furthermore, changes of these structures during the PRN treatment period were also associated with the macular function at the 12^th month, indicating that the structural changes during the PRN period determined the final macular function in AMD patients treated according to the PrONTO study protocol.