Comparison of Longitudinal Changes in Functional and Structural Measures for Evaluating Progression of Glaucomatous Optic Neuropathy

We compared longitudinal changes in functional and structural measures in eyes with glaucomatous optic neuropathy. Circumpapillary retinal nerve fiber layer thickness (cpRNFL) and macular ganglion cell complex thickness (mGCC) were measured using spectral-domain optical coherence tomography (SD-OCT; RTVue). The Spectralis HRA+OCT instrument also was used to measure cpRNFL, and Heidelberg retina tomography II (HRT) and standard automated perimetry (SAP) were performed. Assessments were performed every 3 months over several years. Linear mixed modeling was used to evaluate the rate of change in each measure. Totals of 1406 RTVue, 1366 Spectralis, 1245 HRT, and 1392 SAP measurements were analyzed. Average baseline SAP mean deviation (MD) was -6.24 ± 5.46 dB. Linear mixed modeling revealed that SAP MD changed by -0.23 dB/y (95% confidence interval [CI], -0.34 to -0.12 dB/y). Significant negative trends also were detected in cpRNFL (RTVue, -0.41 μm/y [95% CI, -0.67 to -0.16 μm/y]; Spectralis, -1.36 μm/y [95% CI, -1.65 to -1.07 μm/y]; and mGCC (RTVue, -0.47 μm/y [95% CI, -0.64 to -0.30 μm/y]). Disc rim area remained constant over time (HRT, -0.01 mm2/y [95% CI, -0.03 to 0.01 mm2/y]). The SAP MD, RTVue mGCC, and Spectralis cpRNFL showed the fastest changes in the inferior retina (superior visual field), while RTVue cpRNFL changed the fastest in the superior retina. Functional (SAP) and structural (SD-OCT) testing can detect longitudinal changes of glaucomatous optic neuropathy, but in different ways.