Effect of Phenytoin on the Ganglion Cell Layer in Patients With Optic Neuritis

Phase 2

Completed

Brief Summary: Optic neuritis typically occurs in young (mean age, 32 years), female (77%) patients, and it presents as subacute monocular visual loss that develops over several days.

As yet, treatment with intravenous corticosteroid for optic neuritis had no long-term beneficial effect on vision.

There are a number of factors that contribute to nerve fibre damage including increased level of sodium, so blocking sodium entry could help to protect them against damage.

The main objective of the study is determine whether phenytoin (which blocks sodium entry) can protect nerve fibre and improve final visual function after optic neuritis.

Recruitment & Eligibility

Inclusion Criteria

isolated, unilateral, first acute optic neuritis (confirmed by neuroophthalmologist)
willing to receive a steroidal regimen
no pathologic finding in first oct
no pathology and history of optic neuritis in contralateral eye
<14 days since onset visual loss

Exclusion Criteria

Contraindication or known allergy to Phenytoin
Use of a calcium channel or sodium channel blocker in the past 2 months
Corticosteroid use in the past 2 months
Pregnancy
Significant cardiac, renal or liver abnormalities
Prior clinical episode of optic neuritis in either eye
Bilateral acute optic neuritis
Known ocular or neurological conditions or abnormalities other than refractive error that impair visual function
Refractive error of greater than +5 or -5 diopters
Any condition that may interfere with performance of Optical Coherence Tomography (OCT): corneal, lens or fundoscopic abnormality, a co-morbid ocular condition not related to optic neuritis as detected on the OCT reading

Arm && Interventions

Group	Intervention	Description
placebo	placebo	patients received placebo 100 mg three time daily for 3 months
phenytoin	Phenytoin	patients received phenytoin 100mg three time daily up to 3 months

Primary Outcome Measures

Name	Time	Method
Macular Layer Thickness	Measured at baseline and month 1, 6	macular layer thickness measure in 8 sectors by Heidelberg spectral domain Optical Coherence Tomography
Visual Field Mean Deviation in Decibel	Measured at baseline and month 6	The visual field is performed by the Swedish interactive thresholding algorithm standard 24-2 perimeter (Carl Zeiss mediated, Dublin, California).
Retinal Ganglion Cell Inner Plexiform Layer Thickness	Measured at baseline and month 1, 6	ganglion cell inner plexiform layer thickness measure in 8 sectors by Heidelberg spectral-domain Optical Coherence Tomography
Best Corrected Visual Acuity	at baseline and month 6	Best corrected visual acuity is converted to logMAR (logarithms of minimum angle of resolution) by statistical calculation.

Secondary Outcome Measures

Name	Time	Method
Retinal Nerve Fibre Layer Thickness in Micrometer	Measured at baseline and month1 ,6	Retinal nerve fibre layer thickness measure in 8 sectors by Heidelberg spectral-domain Optical Coherence Tomography