Purpose: To explore structure-function relationships in early glaucoma with spectral-domain optical coherence tomography (SD-OCT) and standard achromatic perimetry.
Methods: One hundred thirty-six eyes of 97 patients with suspected or early glaucoma were enrolled from the clinical database at UCLA's Glaucoma Division. All patients had good-quality peripapillary retinal nerve fiber layer (RNFL)/optic disc measurements and a reliable 24-2 SITA-Standard Humphrey visual field (VF) within a 6-month period. Correlations of global and sectoral RNFL thickness and rim area (RA) measurements, with corresponding global and regional VF sensitivities (both in logarithmic [dB] and 1/Lambert scales [1/L]), were investigated with components of variance models.
Results: The average RNFL thickness, RA, and mean deviation (MD) were 85.6 ± 5.7 μ, 1.0 ± 0.3 mm(2), and -1.3 ± 1.9 dB, respectively. Global RA demonstrated a stronger correlation with MD compared to average RNFL thickness (P = 0.002). The highest correlations were observed between superonasal VF cluster (in dB scale) and inferotemporal RA (R(2) = 0.26, 95% CI: 0.15-0.40) or inferotemporal RNFL thickness (R(2) = 0.24, 95% CI: 0.13-0.37). In glaucoma suspects, the highest correlations were seen between superonasal VF cluster and inferotemporal RA (R(2) = 0.16) in dB scale or RNFL thickness (R(2) = 0.10) in 1/L scale. Correlations were slightly greater with dB scale than 1/L scale and tended to be linear with both scales.
Conclusions: Structure-function relationships can be detected in early glaucoma with SD-OCT. Correlations of RA with VF thresholds tended to be higher compared to those of RNFL. Structure-function relationships were well described with a linear model.