Macular thickness predictive of visual field sensitivity in ischaemic optic neuropathy

Abstract

To investigate the ability of optical coherence tomography (OCT) parameters of macular thickness (MT) and peripapillary retinal nerve fibre layer (RNFL) thickness to differentiate eyes with nonarteritic anterior ischaemic optic neuropathy (NAION) from uninvolved eyes and to identify the relationship between macular and RNFL parameters and visual field sensitivity (VFS). Thirty patients with unilateral NAION participated in a prospective observational cross-sectional study. Patients underwent Humphrey visual field (SITA Standard 24-2, HVF) testing and OCT to measure MT and RNFL. The contralateral uninvolved eye was used as controls. Areas under the receiver operating characteristic curves (AUROCs) of MT and RNFL for discriminating NAION from control eyes were also determined. The prespecified outcome measure was the correlation between RNFL, MT and mean deviation (MD). Average RNFL and MT were thinner in NAION eyes: 72.8 μm versus 98.9 μm (p<0.0001) and 231.9 μm (SD, 21.4) vs. 251.1 μm (SD, 14.8; p=0.0001), respectively. The largest AUROCs were for average MT (0.87) and average RNFL thickness (0.88). Overall, macular parameters showed stronger correlation with VFS than RNFL parameters. The highest correlation was average MT (0.71; p<0.0001) followed by RNFL parameter nasal quadrant RNFL (0.40; p=0.030). Both MT and RNFL show strong correlations with level of VFS in NAION. Macular thickness showed more robust correlations with VF and provides strong surrogate marker of the level of damage in NAION.