Side effects of radiotherapy for eye cancer

There are a number of possible short and long term side effects when you have radiotherapy for eye cancer. There are different ways of giving radiotherapy to the eye.

  • Internal radiotherapy (brachytherapy) - a small radioactive disc is stitched to the eye. This gives a high dose of radiation to the eye cancer.
  • External beam therapy - for this treatment a machine directs radiotherapy beams at the cancer from outside the eye.

Possible side effects depend on:

  • the dose of radiotherapy
  • the type of radiotherapy
  • which part of your eye is treated

Some of the more common side effects are listed below. You may not have all of these. Your eye specialist will go through the possible side effects specific to your treatment.

Short term side effects

The possible short term side effects are:

Loss of eyelashes

Your eyelashes should grow back after your treatment, although maybe not straightaway. Until they do grow back, some people wear false eyelashes.

Increased pressure in the eye

Temporary swelling can cause the pressure inside your eye to rise. Until your treatment is over you have to use eye drops and possibly take steroid tablets to treat this. Laser therapy may be necessary if other treatments do not work.

Feeling tired

You are likely to feel quite tired for a few weeks after your radiotherapy. This is normal but can be frustrating. People tend to think they should have their energy back because their treatment has finished.

What you can do to help:

  • daily light exercise such as walking
  • have a healthy balanced diet
  • rest regularly throughout the day

In time you may notice you are more active and need less rest. Getting back to your usual activity can take time.

Redness around the eye

The skin around the eye can sometimes look red, inflamed and feel sore. You might notice that you have watery eyes. This may not happen until your treatment has finished, and it could last for a few weeks. Gentle washing with water that has boiled and allowed to cool can help. Do ask your radiographer or nurse about caring for your eye. They might recommend a cream you can put on the area.

Sometimes you are prescribed steroid or antibiotic eye drops to treat this. You can also take painkillers to reduce the discomfort.

Sunlight can irritate the eye, so wearing dark glasses when you go outside might feel more comfortable.

Long term side effects

Long term side effects can develop within a few months or take many years. Your team will go through what signs to look for and who to contact if you have any concerns. You have follow up appointments to check for any changes. 

Some possible long term side effects are:


Radiotherapy to the eye sometimes causes a cataract. This is when your lens becomes misty or fogged, so that you can't see clearly. To try to prevent this your specialist shields your lens from the radiation beam if possible.

A cataract after radiation exposure takes a while to develop, perhaps years. If you do get a cataract, you may have an operation to remove it and put in a new lens.

Dryness of the eye

Dryness of the eye can be a short or a long term side effect. During external beam radiotherapy, the gland that makes tears is shielded from the radiation to reduce this side effect. You can have eye drops (artificial tears) to moisten your eye if dryness becomes a problem.

You may need to use these drops every day to stop the covering of the eye (the cornea) from getting inflamed and sore.

Loss of sight

Radiotherapy can sometimes affect eyesight. It is important to contact your eye specialist or GP if you notice changes in your sight.

Damage to the retina (the inner lining at the back of the eye)

Doctors call this radiation retinopathy. Radiotherapy can damage the retinal blood vessels, causing them to bleed, which affects your eyesight. To treat this, you may have:

  • laser treatment
  • steroid injections
  • surgery

These treatments may help to improve your sight.

It is sometimes possible to reduce the radiation damage and hopefully improve or maintain sight by giving injections of drugs into the eye, such as bevacizumab (Avastin). This is a type of anti-VEGF drug which stops the growth of new blood vessels in the eye. Doctors usually use this type of treatment for an eye condition called macular degeneration. 

Optic nerve damage

This is caused by swelling and bleeding of the optic nerve. It can be difficult to treat. Early sight loss cannot be repaired, but it might be possible to prevent further damage. Treatment can include laser therapy and steroid injections into the eye.

Problems with thinking, memory and depression (lymphoma)

If you have radiotherapy for lymphoma, you may have treatment to the brain and spinal cord as well as the eye. Radiation can cause changes to the brain tissue.

This may cause problems with thinking clearly and memory, or depression. This only happens in a small number of adults. If you do develop these side effects, they can appear a few months or several years after you were first treated.

Unfortunately, these late side effects are usually permanent. And occasionally they can become worse over a long period of time.

Seeing a specialist

Let your eye specialist know if you have any of these side effects. It is particularly important to contact your team at the hospital or your GP if you notice any changes in your eyesight. In some cases early treatment can improve some side effects.

Last reviewed: 
12 Oct 2021
Next review due: 
12 Oct 2024
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