The relationship between changes in multimodal imaging methods with electrophysiological change in long-term follow-up in glaucoma disease

Purpose: We aimed to investigate correlations between multifocal electroretinography (mf-ERG) recording and peripapillary retinal nerve fiber layer (pp-RNFL) thickness or thickness in seven macular retinal layers in patients with primary open-angle glaucoma Materials and Methods: This prospective longitudinal study recruited 44 patients with POAG. The cases included in the study were followed up for 12 months. Patients were divided into two groups according to mean deviation (MD) of 24/2 threshold perimetric test as early glaucoma in which MD was -6 or less and moderate to advanced glaucoma in which MD was greater than -6. Best-corrected visual acuity (BCVA), intraocular pressure, central corneal thickness was measured at baseline. Spectral optical coherence tomography (OCT) and mf-ERG was evaluated at baseline, at month 6 and 12. Thickness of seven retinal layer at macula of each ETDRS circles was measured by automated segmentation program of Spectralis OCT. Measurements were compared between groups. Results: Forty-four of the cases included in the study completed the study. Mean age of (25 male and 19 female) patients was 63.4±9.3 years. Difference in BCVA between early and moderate advanced glaucoma groups was not statistically significant. In the second group, the mean ppRNFL measurements at baseline, 6th and 12th months were lower in each chart than the first group. Progression in pp-RNFL at month 12 was not significant between groups. The mRNFL values in the peritentral and peripheral areas were lower in the second group. Thickness of ganglion cell layer, inner plexiform layer and inner nuclear layer was significantly thinner in moderate-advanced glaucoma in all ETDRS sectors. Thickness of other retinal layers was not different between groups. Amplitudes of P1 and N1 waves of mf-ERG in first and second circles decreased but implicit times increased in moderate-advanced glaucoma over 12 months. Depression in amplitudes of P1 and N1 waves corresponded to decreases in pp-RNFL of central and temporal sectors. Thicknesses of inner retinal layers in sectors of all ETDRS circles were correlated with amplitudes of N1, P1, and N2 waves. There was no relationship between outer retinal layer and mf-ERG recordings at baseline or final follow-up. Conclusions: İn moderate to advanced stage glaucoma group patients, the average thickness of ppRSLT was found to be thin in each order. When looking at the retinal layers, it was seen that there were no major changes in the outer layers and that they were more varied in the inner layers. The amplitudes of first and second circle P1 and N2 waves of mf-ERG recordings has decreased in moderate to advanced glaucoma. A positive correlation was observed between the measurements of pp-RNFL and inner retinal layers at macula.