Optic Neuritis

What's going on?

This is inflammation of the optic nerve. It can be related to a demyelinative process, but can also be idiopathic or related to an inflammatory disease.

If I examine the patient, what will I find?

There will be an RAPD (relative afferent papillary defect – where one pupil does not react quite as briskly as the other) . The optic disc will be swollen in one-third of cases. The patient usually has a central scotoma; that is, their central vision is obscured or even lost, but their peripheral vision is usually intact. If you show the patient a red object, it will appear a normal colour when they look at it with their good eye but washed out or darker with their affected eye.

What if I've diagnosed it?

The patient should be referred to the hospital for assessment and confirmation of the diagnosis soon/urgent via letter.

What will the hospital do?

Visual acuity, visual fields and pupil reactions will be documented.

Neuro-imaging is not usually indicated unless there are suspicious features.

The patient may or may not have other neurological deficits.

What do I need to do?

Examine the patient for any other neurological problems. If they do have other such problems, the likelihood of multiple sclerosis (MS) is increased and referral to a neurologist is indicated.

Often the hospital doctor will tell the patient the diagnosis but not explain the exact significance. These patients often quite reasonably look up the disease and are understandably concerned at the possibility of MS. They may require counselling (see What to tell the patient, below).

What to tell the patient

The vision usually gets progressively worse over a period of two weeks and may even go down to hand motion. The hospital should have told the patient to expect this, but the news could still be distressing. After two weeks, the vision tends gradually to improve, with most people recovering their pre-morbid Snellen chart reading vision within six months. They are however often left with some degree of difficulty with their colour vision or depth perception.

MS is indeed a concern, with a significant proportion of patients with optic neuritis (probably up to two-thirds) going on to develop demyelinating disease.

Problems that may arise, and how to deal with them

If the patient has another episode of optic neuritis or develops other neurological symptoms, refer to a neurologist for assessment with a provisional diagnosis of MS.