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

Study Overview
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Brief Summary
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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.

Official Title
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a Phase II Double Blind, Randomized, Placebo Controlled Trial of Effect of Phenytoin on the Ganglion Cell Inner Plexiform Layer (GCIPL) Thickness and Visual Field in Patients With a First Episode of Acute Optic Neuritis

Conditions
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Optic Neuritis

Intervention / Treatment
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* Drug: Phenytoin
* Drug: placebo


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: phenytoin<br>patients received phenytoin 100mg three time daily up to 3 months | Drug: Phenytoin<br>* 100 mg phenytoin three time daily for three months, and phenytoin levels will be taken at one and three months later.<br>* Other names: epanutin;|
| Experimental: placebo<br>patients received placebo 100 mg three time daily for 3 months | Drug: placebo<br>* 100 mg placebo three time daily for three months, and phenytoin levels will be taken at one and three months later.<br>|

What is the study measuring?
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Primary Outcome Measures

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

Secondary Outcome Measures

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