6 - typical optic neuritis

what are the general characteristics of inflammatory optic neuropathy?

1. acute vision impairment (color, contrast sensitivity, VA and VF) with improvement in few weeks

2. unilateral

3. pain esp with eye movements

What does atypical optics neuritis cause?

papillitis → visibly swollen ONH

Where is the inflammation in typical optic neuritis?

retrobulbar → no visible ONH swelling (mild disc swelling is still common)

What is the epidemiology of typical optic neuritis?

ages 15-50 → avg age 32

3:1 female

majority Caucasian

What are the symptoms of typical optic neuritis?

1. acute monocular vision loss

2. pain around eye 1 week before or after visual disturbance onset

3. pain worse with eye movements

4. flashes of light or showers of sparks in vision

5. Uhthoff's phenomenon

what is pain around the eye in typical optic neuritis due to?

pulling on the inflamed nerve sheaths at the attachment sites of the EOM

What are the visual signs of typical optic neuritis?

unilateral:

1. acute decreased VA → mild to severe

2. (+) RAPD

3. decreased color vision/red saturation

4. decreased contrast sensitivity

5. VF defect → may have one in fellow eye as well

What is the most common VF defect in typical optic neuritis?

central scotoma → but can be any VF defect

is the VF defect permanent in typical optic neuritis?

according to ONTT → 56% normalized at 1 yr and 73% normalized at 10 yrs

What does an OCT look like in someone with optic neuritis?

decreased RNFL thickness in eyes with history of optic neuritis

What does an OCT look like in someone with MS?

the RNFL looks different from normal → even if the patient has no history of optic neuritis

What does the fundus look like with typical optic neuritis?

normal (65%)

swollen ONH (35%) → blurred disc margins/filling of cup

ONH pallor (10%)

papillary hemes (6%)

no macular star

What does it mean if you see ONH pallor in someone with typical optic neuritis?

indicated previous optic neuropathy

what signs are likely to show in the fellow eye in typical optic neuritis?

visual field (48%)

color vision (21%)

contrast sensitivity (15%)

VA (14%)

What is the time course of typical optic neuritis?

7-10 days: progressive vision loss

~14 days: vision loss stabilizes

2-8 weeks: vision improvement

What does the final VAs look like for someone who has had typical optic neuritis?

20/40 or better in 87%

20/200 or worse in 8%

what are the residual deficits in typical optic neuritis?

1. color

2. brightness perception

3. contrast sensitivity

4. stereopsis

5. (+) RAPD

6. optic disc pallor

7. increased latency of VEP

What did the optic neuritis treatment trial (ONTT) do?

compared treatment of IV + oral steroids to oral steroids only, and placebo treatment

What were the results of the optic neuritis treatment trial (ONTT)?

IV + oral steroids: faster recovery if 20/40 or worse, but no long term benefit. did delay development of MS (esp those with demyelinating lesions)

oral only: no difference in visual outcomes to other treatments, but had the highest recurrence rate

placebo: no difference in visual outcomes to other treatments, had same recurrence as IV + steroid group

what is the management for optic neuritis?

perform MRI of the brain

what is the treatment for patients with normal MRI?

do not require treatment and recover spontaneously

must follow patient over several weeks to check for improvement

what is the treatment for patients with abnormal MRI or severe vision loss?

should be offered IV methylprednisolone followed by oral steroids to reduce risk of MS and faster visual recovery

What were the results of the 15 year follow up for the optic neuritis treatment trial (ONTT)?

50% of entire study developed MS

72% of those with MRI abnormalities developed MS

What is the most important indicator for patients with optic neuritis developing MS in the future?

presence of lesions on MRI