Optic Nerve Axonal Loss Using Optical Coherence Tomography (OCT) in 93 Patients With Multiple Sclerosis and Comparison With Healthy Subjects

Abstract

Purpose: : To evaluate Optical Coherence Tomography (OCT) in patients with Multiple Sclerosis (MS).

Methods: : Prospective study including 93 consecutive patients. Two groups were studied: 1) patients with MS diagnosis, including patients with or without previous acute optic neuritis(186 eyes), 2) Healthy subjects (30 eyes). Retinal fiber nerve layer (RFNL) was measured using OCT (StratusOCT-fastRNFL thickness software protocol). Kruskal Wallis tests were performed for comparison between RNFL and MS type. A correlation (Sperman coefficient) was computed between RNFL (firstly using the mean of both eyes and secondly the minimum value between both eyes) and EDSS score. Finally, we compared the RNFL between subjects with and without MS. A sub-analysis was done, restricting the group with MS to those without previous acute optic neuritis.

Results: : Of the 93 (186 eyes) included MS patients, 47 had presented previous unilateral or bilateral acute optic neuritis (74 eyes) and 46 (92 eyes) were free of optic neuritis; 60 had a relapsing remitting MS, 8 patients a primary progressive MS, and 25 patients a secondary progressive MS. Median EDSS score was 4. There was no significant relationship among retinal nerve fibre layer thickness and EDSS score or MS type.Average retinal nerve fibre layer thickness for whole MS patients was 90 µm (mean of both eyes) and 84 µm (minimum value of both eyes) versus 104 µm (mean of both eyes) and 101 µm (minimum value of both eyes) for the healthy subjects. (p<0,001) Average RNFL thickness for MS patients without previous acute optic neuritis was 94 µm (mean of both eyes) versus 104 µm for the healthy subjects (mean of both eyes) (p=0,004). There were thus highly significant reductions of retinal nerve fibre layer thickness in affected patients (with or without previous acute optic neuritis) compared with control eyes.

Keywords: neuro-ophthalmology: optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer