Assessment of macular function of glaucomatous eyes by multifocal electroretinograms

Abstract

Purpose: To determine whether significant correlations existed between the morphological and functional parameters of the macular region of eyes with open-angle glaucoma (OAG).

Methods: Forty eyes of 40 OAG patients were studied. The morphological parameters were obtained by optical coherence tomography (OCT), and the functional parameters were acquired by automated Humphrey Field Analyzer (HFA) and multifocal electroretinograms (mfERGs). All of the tests were performed within 6 months of each other. The retinal thickness was determined by OCT in the nine Early Treatment of Diabetic Retinopathy Study (ETDRS) sectors of the macula, the fovea, and the four quadrants of the inner and an outer ring. The amplitudes of the second-order kernel responses of the mfERGs in the central 5° including the amplitude ratio of the nasal to temporal hemispheres (N/T amplitude ratio) were analyzed. The total mean deviation of the HFA corresponding to each OCT region was measured. The correlation between the different parameters was determined by coefficients of correlation and linear regression analyses.

Results: The N/T amplitude ratio of the second-order kernel responses of the mfERGs was significantly correlated with the retinal thickness in the inferior quadrant (r = -0.44; P = 0.004). There was a significant correlation between the N/T amplitude ratio and the threshold in the superior quadrant measured by the HFA Central 10-2 program (r = -0.40; P = 0.011) and also between the N/T amplitude ratio and the total deviation in the superior quadrant (r = -0.40; P = 0.010). There were significant correlations between the inferior retinal thickness and the average threshold and the TD in superior (r = 0.70, P < 0.001; r = 0.692, P < 0.001, respectively), nasal (r = 0.53, P < 0.001; r = 0.53, P < 0.001, respectively), and temporal (r = 0.46, P = 0.003; r = 0.44, P = 0.004, respectively) quadrants.

Conclusions: Functional glaucomatous changes determined by mfERGs and perimetry are significantly correlated with the morphological changes determined by OCT.

Keywords: Humphrey Field Analyzer; Multifocal electroretinogram; Open-angle glaucoma; Optical coherence topography.