Structural and Functional Evaluation of the Retinal Nerve Fiber Layer in Patients With Multiple Sclerosis

Abstract

Purpose: : To evaluate the changes in the retinal nerve fiber layer (RNFL) in patients with Multiple Sclerosis (MS) by means of ocular imaging technologies and functional evaluation.

Methods: : Forty-six patients with MS (92 eyes) were enrolled in this study. None of the patients had an optic neuritis episode in at least 6 months prior to the inclusion or during the follow-up. All patients underwent a complete ophthalmic examination that included visual acuity (logMAR), colour vision (Ishihara pseudoisochromatic plates), refractive evaluation, visual field examination, optical coherence tomography (OCT), scanning laser polarimetry (GDx) and visual evoked potentials (VEP). All the patients were re-evaluated after a period of 12 months in order to quantify any change in the retinal nerve fiber layer.

Results: : All the parameters showed a decrease in the RNFL thickness during the 12-month follow-up greater than the decrease due to the age in healthy patients, although these changes were not detected by the standard automated perimetry. Differences were statistically significant (P<0,05, t test) in the mean and inferior RNFL thickness and macular volume provided by OCT and in the TSNIT SD provided by GDx. The greater differences were obtained in the mean RNFL thickness (89.70 µm vs 87.03 µm). Changes in the optic nerve were detected by structural measurements but not by functional assessments.

Conclusions: : The rate of axonal loss observed in patients with MS was greater than that seen in healthy patients, regardless of the presence of a previous history of optic neuritis. Progressive axonal loss can be detected in the optic nerve of MS patients. Ocular imaging technologies are useful tools to evaluate structural abnormalities in the RNFL and changes in time.

Keywords: astroglia: optic nerve head • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electrophysiology: non-clinical