To describe a technique for evaluating peripapillary and optic nerve head (ONH) anatomy using spectral domain optical coherence tomography (SD-OCT) raster scanning in humans and compare quantifiable parameters between diagnosis categories.
Ninety-five eyes of 51 consecutive patients were evaluated in this retrospective cross-sectional pilot study. Cirrus 5-line raster SD-OCTs with a resolution of 5 to 15 μm obtained through the ONH were included. A single observer manually measured neural canal opening (NCO), prelaminar canal depth (PLCD), peripapillary choroidal thickness (PPCT), and canal nerve fiber layer (CNFL) in normals, ocular hypertension, primary open-angle glaucoma (POAG), low-pressure glaucoma (LPG), secondary glaucoma, and early atrophic age-related macular degeneration. Clinical information, including central corneal thickness (CCT), was obtained via medical record review. Mean anatomical values within diagnosis categories were compared using one-way analysis of variance and multivariate analysis. Bivariate analysis was used to investigate relationships between continuous variables, and significant (p < 0.05) relationships were incorporated into the final statistical model.
Horizontal NCO was significantly greater in eyes with LPG than that in normals (p = 0.021). The PPCT was thinner in age-related macular degeneration (p = 0.001) and glaucoma (p = 0.004) compared with that in controls (normals). Mean CNFL was thinner in POAG (p < 0.001) and LPG (p = 0.053) compared with that in normals. Vertical NCO was inversely correlated to CCT (p = 0.013). Multivariate analysis indicated a positive correlation between PLCD and PPCT (p = 0.008) and an inverse correlation between CNFL and PLCD (p < 0.001). Controlling for PPCT, PLCD and CCT were inversely correlated (p < 0.001).
The SD-OCT raster scanning may be used to quantify ONH anatomy in humans. The NCO differences between POAG and LPG may indicate a distinct structural vulnerability in LPG. In addition, CNFL, PPCT, and PLCD may be important parameters to consider in glaucoma. The PLCD correlates with PPCT and should be considered in new models of glaucoma pathogenesis.