Abstract
Purpose: :
To investigate the nerve-fiber layer thickness (NFLT) reduction rate in classic multiple sclerosis (classic MS) and relapsing neuromyelitis optica (NMO) with/without history of clinically manifest optic neuritis (ON).
Methods: :
The study subjects consisted of 24 patients with classic MS satisfying the International Panel criteria for MS, 6 patients with NMO who showed extensively long MRI spinal cord lesion and/or positive anti-aquaporin-4 antibodies, and 37 age-matched control individuals (male: female = 10: 27, 36.9±10.1 yrs old) who visited glaucoma clinic. All subjects were divided into the following 3 groups, Group A: classic MS without history of symptomatic ON (n=15, male: female = 6: 9, mean age: 40.0±10.7 yrs), Group B: classic MS with ON (n=9, male: female = 3: 6, 31.3±4.6 yrs old), and Group C: NMO (n=6, male: female = 1: 5, 41.3±15.3 yrs old). NFLT was measured at 4 quadrants around the optic disc (Area 1: superior, Area 2: nasal, Area 3: inferior, Area 4: temporal) using 3D Optical Coherence Tomography (3D OCT-1000; Topcon, Tokyo, Japan). For comparison, if the patients had no history of ON, right eye data was chosen, while they had any history of ON, the eye with smaller number of episodes was chosen. The NFLT reduction rate from the average value of control individuals in each quadrant was divided by the number of ON episodes, and was compared between three groups. The Tukey-Kramer test was used for statistical analysis.
Results: :
The decrease in NFLT was more extensive in the order of Group C, B, and A in all quadrants. Mean numbers of ON episodes in Group B and C were 1.2±0.4 and 2.3±1.5, respectively. The NFLT reduction rates per single ON episode in Areas 1 - 4 were 12.5, 19.5, 17.1, and 11.3% in Group B, and 19.7, 20.9, 18.4, and 15.9% in Group C: the difference was not significant between Group B and C. There were no significant differences in the age among all groups.
Conclusions: :
The patients with NMO showed most severe optic nerve damage among the three groups. However, the NFLT reduction rates per single ON episode around the optic disc were similar in patients with NMO and classic MS with ON.
Keywords: optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer