How can a pituitary tumour damage your eyesight?
30 November 2021
What is a pituitary tumour?
A pituitary tumour is a growth on the pituitary gland, and it is counted as a type of brain tumour. The pituitary gland sits a few centimetres behind your eyes and it is responsible for regulating metabolic rate, growth, fertility, menstrual cycle and pregnancy hormones, to name just a few points. The most common issue that people have with their pituitary gland is that they experience a growth on it called an adenoma. This is a type of tumour and it can cause the pituitary gland to produce too many or not enough hormones. In fact, 8% of all brain tumours diagnosed in the UK each year are pituitary tumours.
Aside from this, if the tumour grows to a size larger than 1cm across, it can begin to press on your optic nerve and affect your vision. This occurs due to its extremely close proximity to the back of the eye. We’re now going to look into how the tumour can affect your eyesight and discuss possible treatments to restore any lost vision.
How does a pituitary tumour affect your eyesight?
Almost half of our brain capacity is used for processing visual information. Your brain receives visual signals via the optic nerves (one for each eye), so any obstruction to the nerves caused by the tumour can affect or reduce the amount of visual signals you receive. The two optic nerves meet at the optic chiasm where they merge together. If the pituitary tumour presses again the optic chiasm, there is visual loss in both eyes. If the tumour pushes against just one optic nerve, then that is the eye that will be affected.
One of the first symptoms of a pituitary tumour is reduced peripheral vision. This can happen gradually, beginning as the tumour begins to touch the optic nerve and then increasing in line with the tumour growing and pushing more on the optic nerve. As deterioration of peripheral vision occurs slowly, it can sometimes be difficult to notice the onset of the symptoms.
Another symptom of a pituitary tumour is double vision, caused by the muscles around your eyes not functioning properly. With normal vision, your eyes both work together effectively but if the tumour affects the muscles that pull the eye in the right direction, it can cause the eyes to become misaligned. The means your brain receives two slightly different images, leading to double vision. This is a kind of double vision which is only present when both eyes are open. You can read more about double vision and its other causes on our blog here.
How can you remove a pituitary tumour?
Removing a pituitary tumour is necessary in order to prevent the effects on your vision from becoming worse. Removing the tumour can also restore some of the vision which was previously lost. Thankfully, the surgery can be done using the keyhole method, meaning it’s minimally invasive and has a relatively quick recovery time. Most of the time, the surgery is carried out through the nose or, in other cases, with keyhole surgery incisions via the eyebrow, eyelid or temple area.
If surgery is not an option due to the size of the tumour, there are other options such as medication or radiotherapy to shrink the tumour. This can make it more suitable for operating on at a later date. Alternatively, taking medication to reduce the size of the tumour could even mean that it doesn’t push against the optic nerve so much, therefore potentially restoring any previously lost vision.
Can vision come back after a pituitary tumour?
In around 80% of cases, a patient’s vision comes back following surgery to remove the tumour. This can sometimes happen within a few days after surgery but can also take up to a year in other patients to gradually return. Even if a pituitary tumour has been removed entirely, you are still at a higher risk of it growing back again in the future. For this reason, it’s important to have checks twice a year after the removal of the tumour, just to ensure that your pituitary gland is still healthy and not affecting your vision.
The key takeaway from this blog post is to remember that the earlier the tumour is diagnosed and treated, the better the chances are of your sight returning. As always, try to be aware of any changes to your sight and attend regular eye examinations to ensure that eye conditions or diseases can be picked up and treated quickly.
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