Diabetes & eye problems

If you have diabetes, one of the important regular checks that are needed is for your eyes. This is due to the increased risk of a number of eye problems including cataracts, diabetic retinopathy and glaucoma if you also have diabetes. Keeping your diabetes as well controlled as possible delays or prevents diabetes-related eye disease.

Diabetes can cause several important eye problems such as damage to the retina in the eye (diabetic retinopathy), and it also increases your chances of developing cataracts and glaucoma. This is why eye checks every 1 to 2 years are an important part of your diabetes care, as treatment is possible if found in the early stages.

The best defence against diabetes-related eye disease is keeping blood glucose, cholesterol and blood pressure at healthy levels, not smoking, having your eyes checked every 1-2 years and seeing your doctor or optometrist straight away if any vision problems develop.

When do eye checks start?

  • For Type 2 diabetes, eye checks start from the time of diagnosis. This is because some people may already have signs of diabetes eye disease by this time. 
  • For Type 1 diabetes, eye checks tend to start 5 years after diagnosis, but this can vary depending on your age when first diagnosed. 
  • If no retinopathy, you will be offered an eye screen every 2 years.
  • If there are any signs of eye disease, the eye team will explain what further tests, treatment and follow up is needed. 

Damage can be 'silent'

Diabetes eye damage is sometimes called a 'silent' disease. This is because the damage can be happening a long time before you notice any change in your sight. By the time your sight changes the damage is often very bad. Don't wait until you notice your vision is changing before you have your eyes properly checked.

So, it's really important to:

  • get a full diabetes eye check when you first find out you have diabetes
  • have regular diabetes eye checks every two years once you know you have diabetes
  • if you already have any diabetes eye damage, have checks and treatment as directed by an eye specialist.

How can diabetes affect my eyes?

Just like other parts of our bodies, high blood glucose levels can cause damage to small and large blood vessels. The challenge is you don't have any symptoms until it is well advanced. This is why it is sometimes called a silent disease and needs regular eye checks.

One of the important parts of the front of your eyes is the lens. The lens is like a projector and if it's out of focus or damaged, the picture on the screen will not be clear. In this case, the screen is the retina, a special light-sensitive disc at the back of your eye that picks up the picture coming through your lens. 

Diabetic retinopathy (retina damage in diabetes)

Damage to your retina from diabetes is called 'diabetic retinopathy'. This happens when the blood supply to the retina is damaged from high blood glucose levels in the bloodstream over a long period of time. The blood vessels can become leaky, blocked, or too small to let through enough blood. Over time, this leads to the retina (or screen) being damaged and only some of the information about an image can be transmitted via the eye nerve from the retina to the brain. If the damage is widespread, the whole of the screen can be wiped out and this results in total blindness.

The key risk factors for diabetic retinopathy are:

  • blood glucose control over the long-term
  • blood pressure levels
  • how many years someone has had diabetes
  • family history (genes) 

Read more about diabetic retinopathy

Cataracts

A cataract is when the lens becomes hazy or milky, making vision cloudy or blurry. Cataracts are common as people get older, however for people with diabetes, the risk is doubled (two times more likely). Also the age of onset is younger. If you notice any blurring or worsening of your vision, have your eyes tested.

Cataracts can usually be treated. In the early stages, you may find wearing sunglasses or glare control lenses in your glasses is helpful. As cataracts progress, less light gets through the lens and it is harder to see. Cataract surgery is a very common procedure to remove the lens and replace it with a new implanted lens. You will be able to see more clearly straight away and the surgery can usually be done as a day case. 

Read more about cataracts

Glaucoma

Glaucoma occurs when the pressure in the eye gets too high, causing damage to the optic eye nerve. When this happens, it can cause gradual loss of vision, usually starting at the sides or peripheral vision. This loss of side vision is often not noticed until well advanced when treatment is more difficult. With regular eye checks, glaucoma can be found at an earlier stage and eye drops may be all that is needed to reduce the pressure. In some cases laser treatment or surgery are needed. 

Read more about glaucoma 

How can I delay or prevent eye damage?

You can take care of your eyes when you have diabetes by:

  • having regular full diabetes eye checks
  • working with your healthcare team to keep your diabetes well controlled
  • knowing what your blood pressure is and keeping to target
  • maintaining a healthy blood pressure 
  • if you smoke, doing everything you can to quit – smoking damages your eyes and added to diabetes is a dangerous combination
  • maintaining healthy blood lipids (cholesterol).

If you notice any changes in your sight, see an optometrist or your doctor right away. 

What changes should I watch for?

 Here are some of the vision changes to watch out for. If you notice any of these symptoms, see an optometrist or your doctor right away: 

  • you feel pressure in my eye
  • your vision becomes blurry
  • you have trouble reading or start to see double
  • one or both of your eyes hurt
  • you see spots or 'floaters'
  • you can't see things at the side as you used to.

What is a diabetes eye check?  

A diabetes eye check looks at the back of your eyes (the retina or screen) rather than testing your vision for glasses or driving. It is done by a specially trained health professional either looking at, or photographing, the backs of your eyes (or retinas).

To see the retina, you will usually have drops put in your eyes to dilate the pupils. This makes the black central part of the eye larger until the drops wear off. 

Once your pupils are dilated the person can either shine a light into your eyes to look at the retina themselves or take a photograph of the back of your eye. The advantage of taking a photograph is this can be sent to an eye specialist to review and compared with previous checks.

An eye check for glasses is not the same

Even if you have recently had your eyes tested for glasses or driving, you will still need to have a proper diabetes eye check as these are different tests. When you get your eyes checked by an optometrist for glasses, they are checking the function of the front of your eyes. 

The eye check for diabetes is checking the back of your eye (or retina) as well as the lens. These checks must be done by someone who is specially trained to do diabetes eye checks. In New Zealand, every District Health Board has an eye screening service that is free for people with diabetes.

How do I get a diabetes eye check?

Usually your doctor or nurse will refer you to the local retinal screening service. However you are the most invested in looking after your eyesight, so make sure to check each year if it is due and make sure you get to your appointment. 

  • If your last retinal eye check was normal, make sure it is done every two years. 
  • If you have early, mild or advanced diabetic eye disease, make sure you understand what treatment is needed and anything you can do to slow down the damage to your eyesight.

Learn more

Diabetes and your eyes Save our Sight, NZ Association Optometrists
Diabetic retinopathy Fred Hollow's Foundation 
Diabetic eye screening
NHS Choices (the frequency of eye screening can vary in different countries) 

Credits: Health Navigator Editorial Team.