The relationship between structure and function as measured by OCT and Octopus perimetry

Background/aims To determine the structure-function relationship between equivalent visual field areas obtained with the Octopus perimeter (OP), and the peripapillary retinal nerve fibre layer (RNFL) thickness measured with spectral-domain optical coherence tomography (OCT) in healthy individuals and patients with glaucomatous optic neuropathy. Methods Eighty-eight normal subjects and 150 patients with open-angle glaucoma were prospectively recruited. Eligible participants for the glaucoma group were required to have elevated intraocular pressure and glaucomatous optic nerve head morphology. All participants underwent reliable automated perimetry with OP, and optic nerve head imaging with the Cirrus OCT. Principal component analysis of the mean threshold values for the visual field test points were performed independently for each hemifield. Pearson correlations were calculated between visual field regions and RNFL thickness sectors. Results Mild to moderate correlations were observed between the visual field regions and the peripapillary RNFL thicknesses. Each visual field region was significantly correlated with more than one RNFL sector, and vice versa. The strongest correlation was observed between the RNFL thickness at 5 and 7 clock-hour positions and the superonasal region of OP (r=0.63). Conclusions Retinal sensitivity evaluated with OP correlated moderately well with the RNFL thickness measured by OCT. There was an overlap of the visual field regions within the optic disc.