Sub-clinical atrophy of the retinal nerve fibre layer in multiple sclerosis

This study aimed to evaluate the presence of abnormalities in the retinal nerve fibre layer (RNFL) in multiple sclerosis (MS) patients with normal ophthalmic examination, and to compare the ability of optical coherence tomography (OCT) and scanning laser polarimetry (GDx) to detect axonal loss.

Patients with MS and disease-free controls were invited to enrol in the study from 1 February 2007 to 30 June 2008. Ophthalmic examination, including evaluation of visual acuity (VA) and visual field (VF), showed normal results in all subjects. Retinal nerve fibre layer properties were measured by means of OCT and GDx. Visual evoked potentials (VEPs) were also recorded.

Forty eyes of 40 MS patients and 20 eyes of age- and sex-matched controls were included in the study. Despite normal VA and VF results, significant differences between the two groups were observed in VF mean deviation (MD), most of the RNFL measurements provided by OCT and GDx, and VEP P100 latency and amplitude. There was a significant correlation between OCT and GDx parameters, and between these parameters and VEP results. Nineteen MS eyes (35.7%) showed RNFL abnormalities detected either by OCT or GDx.

Sub-clinical ganglion cell loss can be detected in MS patients with normal visual function. Both OCT and GDx are useful complementary tools with which to identify this damage.