Simulated visual fields produced from macular RNFLT data in patients with glaucoma

Purpose: We investigated in detail the correlation between structure and function in the macula, and whether optical coherence tomography (OCT)-measured macular structure could be used to simulate the visual field. Materials and methods: This study comprised 60 eyes of 34 patients with open angle glaucoma (Anderson-Patella classification). To assess macular function, reliable data from the Humphrey field analyzer (HFA, SITA-standard, 10-2 program) for threshold, total deviation (TD), and pattern deviation (PD) were used. To assess macular structure, thickness data for the retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), and ganglion cell layer plus inner plexiform layer (GCL+IPL) from macular OCT maps (3D OCT-2000, Topcon) were analyzed. Spearman's coefficient of correlation analysis was performed to determine the significance of the correlation, as well as the formula for simulation. The formula was used to calculate the simulated threshold, TD, and PD values. The simulation method was validated by comparing results for simulated and actual visual fields in a new data set of 29 eyes from glaucoma patients. Results: In most test points, macular function and the layer-by-layer structure were significantly correlated, however, the distribution of highly-correlated points varied. Simulated grayscale maps of the visual field based on the formula of regression line for RNFLT and thresholds were similar to actual visual fields. There was a significant correlation between simulated visual fields created from RNFLT, GCC and GCL+IPL data and actual average threshold values in all 68 test points (r=0.63-0.87, p<0.001) and TD (r=0.62-0.86, p<0.001). Conclusion: We found that there was a significant correlation between structure and function in the macular area, and that simulated visual fields from RNFLT data reflected actual visual fields. Such a simulation of macular function from OCT parameters may be useful in assessing glaucoma in patients who have difficulty undergoing actual visual field examinations.