Correlations of Retinal Nerve Fiber Layer, Optic Disc and Ganglion Cell Complex Parameters of Fourier-Domain Optical Coherence Tomography with Visual Field Loss in Japanese Glaucoma Patients

Abstract

Purpose: : To evaluate and compare the degree to which the retinal nerve fiber layer (RNFL), optic disc and ganglion cell complex (GCC) parameters of RTvue Fourier-domain optical coherence tomography (Optovue Inc, Fremont, CA) correlate with visual field loss in Japanese glaucoma patients.

Methods: : Using RTvue (software version 4.0), RNFL (average RNFL thickness), disc (cup area, cup/disc area ratio, rim area, rim volume, nerve head volume, and cup volume), and GCC (average GCC thickness) parameters were measured in 110 eyes of 110 Japanese glaucoma patients. Correlation coefficients (CCs) of the RNFL, disc and GCC parameters, with mean deviation (MD) (Humphrey Swedish interactive threshold algorithm standard 30-2 program), were calculated and compared.

Results: : MD, average RNFL thickness, cup area, cup/disc area ratio, rim area, rim volume, nerve head volume, cup volume and average GCC thickness averaged -6.41 (standard deviation 7.42) dB, 85.61 (14.59) µm, 1.27 (0.66) mm², 0.65 (0.26), 0.59 (0.38) mm², 0.072 (0.101) mm³, 0.126 (0.151) mm³, 0.409 (0.334) mm³ and 80.63 (11.23) µm, respectively. The CCs of the average RNFL thickness, cup area, cup/disc area ratio, rim area, rim volume, nerve head volume, cup volume, and average GCC thickness, with MD, were 0.591 (P<0.001), -0.083 (P=0.387), -0.198 (P=0.038), 0.264 (P=0.005), 0.089 (P=0.358), 0.117 (P=0.223), 0.116 (P=0.226) and 0.615 (P<0.001), respectively. The CCs for both the average RNFL thickness and the average GCC thickness were significantly higher than that for the rim area, which showed the highest CC among the disc parameters determined (P<0.001). The CC for average RNFL thickness did not differ significantly from that for average GCC thickness (P=0.583).

Conclusions: : Average RNFL thickness, rim area and average GCC thickness, as determined by RTvue, correlated significantly with visual field loss in Japanese glaucoma patients. Average RNFL and GCC thicknesses showed a similar degree of correlation, with these parameters providing stronger correlations than the rim area.

Keywords: imaging/image analysis: clinical • nerve fiber layer • optic disc