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

Abstract

Purpose: We compared longitudinal changes in functional and structural measures in eyes with glaucomatous optic neuropathy.

Methods: 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.

Results: 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.

Conclusions: Functional (SAP) and structural (SD-OCT) testing can detect longitudinal changes of glaucomatous optic neuropathy, but in different ways.