I received my annual MRI result at the end of January and it seems that nothing much has changed in a year, although Fuss seems to have increased in size by about 1mm and is now 12mm in circumference, according to the report. I contacted my radiation-oncologist and suggested that perhaps there was no need for her to see me and she agreed, but she will arrange for a further MRI in a year's time as usual.
I did receive an appointment with a new neurologist prior to the MRI. This went OK and he suggested a check of my blood and a review in one year. So THAT is THAT for another 12 months! I did tell him about the jerky limb movements that have developed (ataxia) in the past year and also the double vision, but of course neither happened while I was at the appointment! Sod's law, isn't it?
With regard to the ataxia I have since found out that this can be a side effect of the drug Carbamazepine (Tegretol). I have been on the drug more or less continuously for the past 3 years following severe Trigeminal Neuralgia affecting the left side of my face. Carbamazepine has been shown to be extremely effective in controlling the spasms of TN. Anyway, I decided to slowly wean myself off over 3 weeks or so just in case this was the cause of my problem and, much to my DELIGHT, those jerky leg and arm movements have STOPPED! What a relief!
However, the double-vision (diplopia) remains a nuisance and I intend to see my family doctor about it next week. It seems it might be "binocular double vision" because if I close or cover one eye when it occurs the image is no longer 'double'. I do wonder if Fuss is causing this as he's sitting close to the oculomotor nerve which is responsible for movement of the eyes and eye-lids. It seems possible.
What worries me is that, if the double vision cannot be cured and continues to get worse, it may mean I am no longer able to drive. Meanwhile, if you see a senior citizen driving along with one eye shut you will know its me .... and I'm definitely not winking!
Causes of double vision
Double vision can occur in one or both eyes, and can be caused by several different conditions.
Double vision in one eye (monocular)
Double vision in one eye is known as monocular double vision. Double vision continues when the unaffected eye is covered, but you should be able to see normally when the affected eye is covered.
It can be caused by:
- an irregularly shaped cornea (astigmatism), which is a refractive error
- dry eye, which is when your eye does not produce enough tears
- abnormalities of the cornea
- abnormalities of the lens, such as cataracts (cloudy patches over the lens)
- abnormalities of the retina, such as macular degeneration
The cornea is located at the front of the eye and acts like a camera lens, helping to focus the light coming into the eye.
The retina is a light-sensitive layer of tissue at the back of the eye that converts light entering the eye into electrical signals.
Monocular double vision is rare. Astigmatism and cataracts are the most common causes.
Double vision in both eyes
Double vision caused by both eyes failing to work together properly is known as binocular double vision. If you have binocular double vision, your vision will usually be normal if either eye is covered.
If you have binocular double vision, your eyes will point at slightly different angles, causing them to send different images to your brain. The images from each eye are too different for your brain to create a clear, single image. This results in you seeing double images.
Conditions that can cause double vision
In adults, if double vision develops suddenly and isn't caused by a childhood squint, it may be a sign of another condition affecting the free movement of the eye, or the muscles, nerves, or brain. Conditions may include:
- a thyroid condition affecting the external eye muscles – your thyroid gland is found in your neck and produces the hormone thyroxine
- a condition affecting the blood vessels supplying blood to the brain, or to the nerves controlling the eye muscles (for example, a strokeor a transient ischaemic attack)
- diabetes – which can damage the blood vessels supplying blood to the nerves of the eye muscles
- myasthenia gravis – which causes the body's muscles to become weak, including the eye muscles
- multiple sclerosis – which affects the central nervous system, including the nerves of the eye muscles
- an aneurysm – a bulge in a blood vessel caused by a weakness in the blood vessel wall, which can press on a nerve of the eye muscle
- a brain tumour or cancer behind the eye that prevents free movement or damages the nerves to the eye muscles
- a head injury damaging the brain or the nerves that move the eye muscles, or damages the eye socket and restricts the movement of the eye muscles