Diplopia means double vision, that is to say a patient seeing two images of a single object. This can occur some of the time or all of the time. The images can also be separated in the visual field horizontally or vertically.
Double vision can happen in one eye which is called ‘monocular’ or both eyes called binocular. It is possible to tell which type you have by simply covering one eye. If your double vision disappears when you cover either eye it indicates both eyes are affected. If it stays when you cover one eye then it’s most likely monocular double vision. A third type of diplopia is termed ‘physiological’.
There are other symptoms you may experience too including, but not limited to: headaches, migraines, nausea, droopy eyelids, pain with regular eye movement, and pain around the eyes.
Occasionally double vision can be an indicator of something more serious or a more immediate underlying medical issue. If double vision is accompanied by pain or severe headache then it’s important to seek medical attention as soon as possible.
The ocular muscles around the eyes are what help us to look directly at an object without double vision. They are also crucial in helping us judge distances and gauge depth of field. If for some reason this muscle balance might fail or something interferes with these ocular muscles then the result is usually diplopia.
Let’s look at the three categorisations a little more closely. Physiological, binocular or monocular:
Physiological diplopia is a normal occurrence and will be familiar to some people. It’s when an object that’s out of your central field of vision is seen as double. The brain will normally compensate for this and most people will be unaware of it.
Any problem that affects the extraocular muscles – the muscles that control the direction of the gaze – can cause diplopia. Dysfunction of these extraocular muscles can be caused by brain damage, infection, multiple sclerosis, stroke or head trauma. A brian tumour can also cause eye damage.
There are several conditions that can also contribute to binocular diplopia:
This disease can lead to problems with the nerves that control eye muscle movements. Sometimes this can happen before the person is aware that he or she has diabetes.
This is the most common cause of an overactive thyroid (hyperthyroidism). Some people with Graves’ disease also develop double vision due to swelling and thickening of the muscles that move the eyes within the eye socket.
The bones around the eye socket are very think so trauma to those bones can damage the muscles can cause diplopia.
The treatment of double vision depends on the underlying cause. In simple cases it might just be treated with wearing a patch over the eye or an opaque contact lens or eye movement exercises. If there is rapid onset of diplopia and there are concerns of a brain tumour then an urgent referral is needed
If regular symptoms persist then a patient should also expect to be referred. Persistent symptoms would include headache.
Monocular double vision
Monocular diplopia can be linked with abnormalities in the cornea that is distorted or scarred, cataract, retinal conditions and several other factors.
Monocular double vision could be an indicator that someone needs glasses. However a developing cataract can also cause monocular diplopia.
If you have a diagnosis of diplopia then you need to stop driving. Driving can resume if the condition is corrected either by glasses or by wearing an eye patch.
The first step in diagnosis is identifying which type of diplopia a patient has and whether it is monocular or binocular. With monocular diplopia you will be referred to see an ophthalmologist. If the problem is binocular then your GP will likely try and rule out other factors like trauma, diabetes, Grave’s disease or a neurological disorder.
In diagnosing binocular diplopia, your doctor has to determine which eye muscles are affected. To do this, you will be asked to look at the doctor’s finger as he moves it up, down, left and right. This lets the doctor see how far your eye can move in each direction. Your doctor also will cover one eye and then the other, while you focus on a target. If the doctor sees your eyes shift as the eye cover is moved, it means your eyes are not aligned properly.
Blood tests are used to identify whether the problem is a hormonal one. And if there is a suspicion that something is affecting the nerves in your eyes then an MRI scan or CT scan may be necessary.
In most cases, double vision is easy to pinpoint in adults, because they can describe their symptoms. In children and younger people it is more difficult. The duration of your double vision will depend on what the underlying cause is. Cataract, for example, can be corrected almost immediately with surgery.
Some cases of double vision can be prevented. Sensible precautions such as wearing a helmet for cycling or goggles for sport or work if you are in a higher risk job, can all help reduce the possibility of trauma. People with diabetes can decrease their chance of nerve damage, which can lead to double vision, by controlling blood sugar. There is no way to prevent age-related cataracts or some other forms of double vision.
Laser surgery can be used to treat a host of conditions that cause Diplopia. Book an appointment to speak to Laser Vision Scotland about your best treatment options.