Initial Pattern of Optic Nerve Enhancement in Korean Patients with Unilateral Optic Neuritis

PURPOSE: The purpose of this study was to demonstrate whether the pattern of optic nerve enhancement in magnetic resonance imaging (MRI) can help to differentiate between idiopathic optic neuritis (ON), neuromyelitis optica (NMO), and multiple sclerosis (MS) in unilateral ON. METHODS: An MRI of the brain and orbits was obtained in patients with acute unilateral ON. Patients with ON were divided into three groups: NMO, MS, and idiopathic ON. The length and location of the abnormal optic nerve enhancement were compared for ON eyes with and without NMO or MS. The correlation between the pattern of optic nerve enhancement and the outcome of visual function was analyzed. RESULTS: Of the 36 patients with ON who underwent an MRI within 2 weeks of the onset, 19 were diagnosed with idiopathic ON, 9 with NMO, and 8 with MS. Enhancement of the optic nerve occurred in 21 patients (58.3%) and was limited to the orbital segment in 12 patients. Neither the length nor the location of the optic nerve enhancement was significantly correlated with visual functions other than contrast sensitivity or the diagnosis of idiopathic ON, MS, or NMO. Patients with greater extent of optic nerve sheath enhancement and more posterior segment involvement showed higher contrast sensitivity. CONCLUSIONS: Our data revealed that the pattern of optic nerve enhancement was not associated with diagnosis of idiopathic ON, NMO, or MS in Korean patients with unilateral ON. We believe further studies that include different ethnic groups will lead to a more definitive answer on this subject.

Considering Spherical Aberration in Choosing the Wavefront Map for Laser Vision Correction

PURPOSE: To report the dynamic nature of human optical aberrations in the scotopic condition. METHODS: A total of 20 eyes who were candidates for laser vision correction were included in the present study. Repeated wavefront data were obtained using WavescanTM (AMO/VISX). From the wavefront analysis data, the sphere, astigmatism, average pupil size, spherical aberration, coma and trefoil were selected and used to investigate any correlation among the parameters. RESULTS: The sphere, spherical aberration, coma and pupil size showed a dynamic change in the scotopic condition. The spherical aberration and pupil size decreased by the amount of 0.10 +/- 0.04 microm and 0.55 +/- 0.37 mm as the sphere changed 1 D in myopic direction. There was significant positive correlation between the sphere and spherical aberration in 13 eyes of 9 patients (65%), between the sphere and pupil size in 5 eyes of 4 patients (25%), and between the sphere and coma in 3 eyes of 3 patients (15%). The spherical aberration decreased significantly in 4 eyes of 4 patients (20%) as the pupil size decreased. CONCLUSIONS: The optical aberration of human eyes showed a dynamic nature in the scotopic condition. In particular, there was significant correlation between the sphere and spherical aberration. The observed correlations have the potential to be used as helpful indicators to select the optimal wavefront data for the laser vision correction.