vision? How to tell
if it's optic neuritis
What are the signs of peripheral vision loss?
There are various signs to look out for which could indicate an issue with peripheral vision.
It can happen suddenly, or you might not even notice the gradual constriction of your visual field, until it starts interfering with your day-to-day life. Some of the common signs and symptoms of peripheral vision loss may be:
Finding driving difficult
Frequently tripping over obstacles while walking
Finding it difficult to carry out normal tasks in low light conditions
People of any age can develop peripheral vision loss, although it can be more common as we age1. Depending on what is causing the peripheral field change, it could be temporary or permanent and may affect one or both eyes. Some common conditions that adversely affect peripheral vision are:
Strokes or occlusions (a blockage of a blood vessel or hollow artery)
Brain damage from disease
Nerve compression (pressure on the optic nerve)
Drug and alcohol abuse
While each of these conditions presents a unique set of associated symptoms, some, like glaucoma and optic neuritis, can be harder to diagnose because some signs and symptoms can be so similar.
Your optometrist will, of course, know the differences between the two. Nevertheless, it’s important for those being diagnosed to recognise the intricacies between the two in order to help further understand either condition better.
What is glaucoma?
Glaucoma is an eye condition typically associated with problems with the eye’s natural intraocular pressure (IOP). The sensitive nerve fibres at the back of the eye responsible for eyesight can be affected by a rise or imbalance in the eye’s pressure. Glaucoma happens when this causes damage to the optic nerve and affects vision. In rare cases, if the condition is left untreated, it can eventually progress to loss of eyesight.
Since most types of glaucoma are painless and slow-progressing, most people don’t usually notice this loss of vision until it becomes more significant. This is why having a regular eye test, at least every two years or more frequently if recommended, is so important. Acute forms of glaucoma, however, may be accompanied by shooting pain, nausea, haloes and sudden loss of vision. You can learn more about glaucoma in our dedicated resource.
Symptom differences between glaucoma and optic neuritis
While these two eye diseases are very different, there are some similarities which could cause confusion when trying to understand any symptoms that may be presenting themselves. Here are some key symptoms of glaucoma and optic neuritis, to help you differentiate between the two.
It’s important to recognise that these are only general guidelines, however. If you experience any of the below symptoms or are at all concerned about your eye health, then we always recommend a visit to your local optometrist.
Clarity of vision
In the case of optic neuritis, visual acuity usually reduces suddenly. However, in glaucoma, it’s your peripheral vision that can blur, with central vision remaining clear and intact.
Visual field pattern
Glaucoma-induced loss of visual field tends to have a pattern, and typically affects the far peripheral vision — beginning in a small area of the visual field first. This may progress to affect the top half, bottom half or both halves of your peripheral visual field, usually in an arc-shaped pattern.
In optic neuritis, however, there may be an overall decline seen in visual field testing, with some blind spots. Colour vision is often affected, too, with people finding that red can especially appear washed out, or desaturated. The individual may also see occasional flashes of light.
The reaction of the pupil to light is an important factor in making the correct diagnosis3. Relative Afferent Pupillary Defect (RAPD) is a classic sign of optic neuritis, for example. This is where the pupil dilates in response to light instead of constricting. It may also respond differently to light shone in one eye at a time, even with very mild optic neuritis.
A glaucoma-affected eye, on the other hand, may have a sluggish pupil reflex, except in the case of acute glaucoma, where the pupil may be mid-dilated and fixed.
Unless acute, glaucoma is characterised by a gradual and painless loss of vision. However, in the case of optic neuritis, the individual may feel some pain, especially during sideways movements of the eyes.
Sudden vision loss in most cases is, of course, a medical emergency. It should categorically be addressed by a professional without delay to avoid further or permanent loss of vision.