Optic neuritis can be detected during an eye examination. It’s important you keep up to date with your checks, we’d recommend you have one every two years.

What is optic neuritis?

Optic neuritis is an inflammation of the optic nerve. Your optic nerve’s job is to send messages from your eye to your brain — if it’s affected you can experience problems with your vision.

Optic neuritis is common among those who suffer from multiple sclerosis (MS) when the immune system attacks the fatty coating, called myelin, that protects the optic nerve. When the myelin is damaged, the optic nerve can’t send the right signals to the brain and this can lead to changes in vision.

Symptoms of optic neuritis

Optic neuritis usually develops quickly, over hours to days. The following symptoms are linked with optic neuritis:

Some of these symptoms are associated with other, more common eye conditions. However, if you are experiencing any of these symptoms or a sudden change to your vision you should get your eyes checked as soon as possible.

Optic neuritis can occur in both adults and children. It typically affects one eye in adults but often affects both eyes in children.

The majority of people recover over a period of a few weeks. In chronic cases, it can take far longer to recover but rarely more than one year. In general, you’ll regain full, or nearly full, vision although problems with night vision or seeing colours washed out can persist.

Causes of optic neuritis

The cause of optic neuritis isn’t always clear.  However, it is a common condition among those who have multiple sclerosis (MS), inflammation of the optic nerve being caused by damage to the myelin sheath around the nerve. Once the myelin is inflamed it causes pain and disrupts the optic nerve’s ability to send messages from your eyes to the brain, although it’s not known why this happens.

According to the MS Trust, around seven out of ten people with MS will experience optic neuritis at some point.1  Find out more about MS eye conditions here.

Although rare, optic neuritis can also be caused by infections, such as:

  • Mumps
  • Measles
  • Tuberculosis
  • Lyme disease
  • Sinusitis
  • Shingles

How is optic neuritis diagnosed?

During an eye test, optometrists can do some targeted tests that check things like colour vision, how eyes respond to light, how well the eye can see detail and your ability to read the letters in a Snellen chart. Often, as well as routine eye examinations, they’ll recommend an OCT scan to allow them to see the layers of the retina.

If your optometrist suspects you have optic neuritis, they’ll refer you to a hospital eye department where your diagnosis will be confirmed, and a treatment plan developed. Optic neuritis almost always requires further testing and evaluation via referral from your optometrist in order to understand the cause of the inflammation.

Can an OCT scan help detect optic neuritis?

One way to detect optic neuritis is by performing an OCT scan. Optic neuritis can cause changes to the thickness of the layers of the eye, particularly in the retina and the tissues of the optic nerve itself. The retina is the innermost, light-sensitive membrane in the eye and consists of several layers.

The optic nerve carries electrical impulses from the eye to the brain, which are then processed to give us vision. Each nerve contains around a million fibres that receive information from the rods and cones of the retina. Damage to these delicate structures can, in some cases, cause loss of vision.

An OCT scan creates a composite image of the various layers of the optic nerve and retina to allow optometrists to measure their thickness, including the thickness of the retinal nerve fibre layer (RNFL). OCT also provides direct visualisation of the optic nerve. Optometrists can then make informed decisions about suspected optic neuritis, based on the thickness of these layers and the appearance of the optic nerve, as well as their findings from your eye test.

Can optic neuritis be misdiagnosed?

Several eye conditions such as anterior ischemic optic neuropathy (AION) and Leber’s hereditary optic neuropathy (LHON), have similar characteristics to optic neuritis, although their treatment is very different.2 

It’s therefore important for optometrists to get a clear assessment of the eye in order to allow them to refer you urgently to a specialist eye doctor (ophthalmologist) who can confirm the diagnosis of optic neuritis, and advise on the appropriate management.

Latest technologies and new imaging tools such as OCT scanning can help reduce the risk of misdiagnosing cases of optic neuritis. OCT allows the optometrist to see detailed images of the eye and pick up the specific features associated with each of these conditions. The presence or absence of characteristic signs on OCT can help differentiate between eye conditions that closely mimic optic neuritis.

Optic neuropathy

Optic neuropathy is categorised as damage to the optic nerve, from any cause, and there are a few different types. Anterior ischemic optic neuropathy (AION), for example, is the loss of vision caused by damage to the optic nerve as a result of insufficient blood supply. This type of optic neuropathy specifically can cause similar visual field issues to glaucoma, and so can resemble the appearance of it.

While many people with glaucoma have raised eye pressure, there is also a smaller subsection of people who can have normal IOP which can lead to AION being mistaken for normal-tension glaucoma.

Although there are some similarities between AION and glaucoma, there are also many differences. Your eye care professional will be able to tell some key differences: the narrowed rim and deeper cupping of the optic disc is one way to differentiate between the two conditions.

There are further medical investigations also can be done, depending on your other symptoms and history. For example, AION is much more likely to present with sudden visual loss than glaucoma, and people with AION may have a history of vascular disease.

Treatment of optic neuritis

If optic neuritis is confirmed, a treatment plan will be developed for you by an ophthalmologist.

OCT also plays an important role in managing the condition and monitoring the treatment process. Measurements of the thicknesses of various layers of the eye can be repeated over time and the changes documented.

Keeping track of the thickness of these layers helps your ophthalmologist to assess the progression of your condition and how well you respond to treatment. If they need to, they can then make changes to your management plan.

Noticed a change in your eyesight?

It’s important to get regular eye tests every two years. Routine eye tests help your optometrist to spot any potential signs of optic neuritis early on and ensure treatment is started as soon as possible.

Learn more about optic neuritis and OCT testing on our OCT page, or, if you’re concerned about any symptoms, book an appointment at your local store. Head to our eye conditions hub for more information on other vision problems and symptoms.

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References

  1. MS Trust, Optic Neuritis (2018). Available at: https://mstrust.org.uk/a-z/optic-neuritis [Accessed Nov 2021]
  2. Hoorbakht H, Bagherkashi F. Optic neuritis, its differential diagnosis and management. Open Ophthalmol J. 2012;6:65–72. [Online]. Available at: https://www.ncbi.nlm.nih.gov/p... [Accessed Nov 2021].
  3. Dias DT, Ushida M, Battistella R, Dorairaj S, Prata TS. Neurophthalmological conditions mimicking glaucomatous optic neuropathy: analysis of the most common causes of misdiagnosis. BMC Ophthalmol. 2017;17(1):2.
  4. Siddarth Rathi, MD, MBA, and David S. Greenfield, MD Beware the Impostor: Differentiating glaucoma from anterior ischemic optic neuropathy. Glaucoma Today, May/June 2017