This will be a single-blind, randomized comparison study between 1000mg IV methylprednisolone
daily for three days and 1250mg oral prednisone daily for three days of the recovery of optic
nerve function in acute demyelinating optic neuritis. We will be comparing assessments at
baseline, prior to corticosteroid treatment, with assessments at one and six months post
corticosteroid treatment.
Patient Population
We propose to study patients with acute demyelinating optic neuritis where treatment with
high dose corticosteroids is being considered. This presentation can be either the first
presentation of a demyelinating event (CIS) or in a patient with a previous diagnosis of CIS
or MS but must be the first presentation of ON in the affected eye.
Subjects will be recruited from out-patients assessed for acute demyelinating optic neuritis
by neurology, ophthalmology, neuro-ophthalmology at London Health Sciences Center and St.
Joseph's Health Care Center in London, Ontario. Subjects will be included only if the first
visit takes place within 14 days of symptom onset. Only subjects where the physician who
identifies/diagnoses the optic neuritis is considering corticosteroid treatment will be
contacted for potential screening and enrollment. To ensure treatment is chosen based on the
clinical judgement of physician diagnosing ON, the investigators will only contact potential
subjects after the decision to use corticosteroids has been made by the patient's treating
physician.
Primary and Secondary Endpoints
The primary measure will be the P100 latency of the Visual Evoked Potential in the affected
eye at six months. Secondary measures will include high contrast visual acuity and contrast
sensitivity at one and six months post corticosteroid treatment and the P100 latency at
one-month post corticosteroid treatment.
Visual Evoked Potentials VEPs will be recorded with Teca Synergy equipment (Viasys
Healthcare). To ensures consistency in technique, the same technician will perform all three
assessments (day 0, 30 and 180) on the same patient. The subject's skin will be cleaned for
electrode placement. The scalp electrodes will be placed relative to bony landmarks, as per
International Society for Clinical Electrophysiology of Vision (ISCEV) standards (40). The
electrodes will be positioned 5 cm above the inion for Oz (active), mid-forehead for Fz
(reference) and on the right arm for the ground, following ISCEV guidelines. The patient will
be positioned comfortably in a chair with the eye at a distance of 1 meter from a 17-inch
cathode ray tube (CRT) monitor, which has been found to be superior to an LCD monitor as the
latter can cause a delay in the latency. The room will be darkened to minimize extraneous
light that produce responses in the visual cortex and interfere with the VEP response. The
same room will be used for every VEP in this study. The subject will be monitored for
fixation as poor fixation can affect the P100 peak time and an eye patch used to isolate
vision from one eye only. Monocular stimulation will occur at a frequency of 2 Hz, beginning
with the unaffected eye, averaging 200 individual responses for each trial. A minimum of two
trials per eye will be performed as per ISCEV guidelines. Further averaging of additional
trials may be done if there are obvious technical problems (with visual fixation for
instance). As the test is dependent on subject compliance, the following will take place to
maximize compliance and technical aspects of the recording: talking and gum chewing will be
prohibited; the subject will be instructed to relax all muscles of the head and neck
specifically the jaw; feet will be resting flat on the floor with hands relaxed in the
subject's lap; coaching will take place to help diminish any anxiety; the importance of
fixation will be emphasized and the need to resist following the changes in colour of the
checkerboard pattern and to continue fixating on the red fixation square in the centre of the
monitor will be explained. The interpretation of the VEPs will be done by an assessor blinded
to the treatment arm received.
Visual Acuity Visual acuity will be measured using the Early Treatment Diabetic Retinopathy
Study (ETDRS) charts and standard protocol as it the gold standard for ophthalmology clinical
trials using visual acuity as an outcome. Testing acuity occurs initially at 4 meters
initially and only testing at 2 meters if there are no abnormalities noted at 4 meters.
Contrast Sensitivity Contrast sensitivity will be measured using the Low Contrast Sloan
Letter Charts that was found to be valid and reliable for the MS population