Diabetic retinopathy | Kinonga karu nā te matehuka

Diabetes can increase your risk of several eye conditions, including diabetic retinopathy, cataract and glaucoma. Diabetes is the commonest cause of blindness and vision impairment in people aged 20–60 years.

• Compared to the general population, people with diabetes have about 25 times greater risk of vision impairment.
• At least one-third of people with diabetes have retinopathy. 
• Retinopathy threatens vision, or has already destroyed sight, in 10% of people with diabetes.

Early detection of eye conditions means treatment can be given to slow or prevent vision loss.

Read more about eye problems and diabetes.

Diabetes damages the blood vessels that supply the retina of your eye. When signs of damage are detected, you have retinopathy.

The retina is a very thin and complex layer that lines the back and inner wall of your eye. It contains photoreceptor cells, which convert light to chemical and electrical energy. This is then conveyed to your brain via other retinal cells, the optic nerve and the visual nerve pathways to produce your sense of vision. 

If the retina is damaged, especially in its central area, the macula, there is a loss of sight that can't be regained.

Diabetes causes the small blood vessels within the retina to occlude (close up) and/or leak blood, fats and fluid. There are toxic to your retina and cause 2 types of major damage:

• retinopathy
• maculopathy.

What is retinopathy?

Closure of small blood vessels leads to rapid growth of abnormal blood vessels which are fragile and may bleed into the vitreous, the ‘jelly’ of the eye which fills the space between the retina and the lens, and may eventually cause the retina to detach.

What is maculopathy?

Leakage within the macula, especially of fluid and fat, destroys the retinal photoreceptor and nerve cells, and reduces vision.

Retinopathy can occur in both type 1 diabetes and type 2 diabetes.

Those most likely to develop retinopathy are people:

• who have had diabetes for many years – the risk increases progressively each year from the time of diagnosis, and after 15 years, 3 out of 4 people will have retinopathy
• whose diabetes is poorly controlled – strict blood glucose control is the most important factor in the prevention of both the development and progression of retinopathy
• with hypertension (high blood pressure) and abnormal blood fats
• with kidney disease.

Also be aware that retinopathy can get worse more quickly for people with diabetes who also:

• are pregnant
• have poor glucose control
• have high blood pressure.

Diabetes eye checks every 2 years are an important part of your diabetes care, as treatment is possible if these conditions are found in the early stages. However, if you notice any changes in your vision, see your doctor or optometrist right away.

A diabetes eye check looks at the back of your eyes (the retina) rather than testing your vision for glasses or driving. It is done by a specially trained health professional either looking at, or photographing, the back of your eyes (retinas). This is known as retinal screening and you can look for a retinal screening provider near you by entering your address into this search on the Healthpoint directory(external link).

If they diagnose retinopathy, it will be graded according to severity:

• minimal/ mild/ moderate – no immediate threat to sight
• pre-proliferative, proliferative/pre-maculopathy/maculopathy – sight threatened or already lost
• advanced – irretrievable sight loss.

Laser treatment

Laser treatment is aimed at reducing the demands of the ‘sick’ retina on the eye. As such, there is a smaller risk of new blood vessels forming or blood vessels leaking.

Macula laser treatment 

This ‘dries up’ the fluid and exudates – but may take several months, and two to three treatments to be effective.

Overall retinal laser treatment

A laser burns throughout the retina, causing the fragile abnormal blood vessels to disappear, or never develop. Again, several treatments may be necessary for each eye. Where treatment has to be extensive there will be some loss of side vision and night vision. 

Intraocular injections

You may be offered injections of medicines that reduce the swelling and leakage of blood vessels. This is usually offered as a course of treatment and, in some instances, could be performed as a monthly injection. Common medicines include Avastin, Lucentis, Eyelea and Triamcinolone. Your eye doctor will discuss the side effects of medicines and the treatment regimen.

Measures to preserve eyesight include the following:

• Minimise the risk of retinopathy by strict control of blood glucose.
• Have treatment for abnormal blood pressure and fats in the blood (lipids) which cause additional harm to the eyes if not controlled. See also high blood cholesterol
• Once someone is diagnosed with diabetes, you need a retinal eye screen test at least every 2 years.
• Once changes are found, this may become every year or less.  Remember, vision may be normal, but retinopathy could be present.
• Follow medical advice about diet, exercise, medications for diabetes, blood pressure and abnormal blood lipids.
• Do not smoke – this causes strokes, heart attacks and poor circulation in the legs which may result in amputation. 

Regular eye examinations for retinopathy

Once you have diabetes, make sure you get regular retinal examinations at least every 2 years because there is no other way of detecting retinopathy.

• 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 you have any type of diabetes and become pregnant, have an eye check in the first trimester. 
• If you have no damage to your retina, 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. You may also need eye checks more often than every 2 years. Do not wait until you have any eye symptoms or vision problems. This can be too late.

Benefits of regular eye examinations include:

• picking up retinopathy early
• making sure you get treatment at the right time to prevent visual loss or blindness
• with early detection and adequate treatment, up to 98% of severe vision loss (bilateral blindness) can be prevented.

Apps reviewed by Healthify

You may find it useful to look at some Diabetes apps.

Are eye checks needed if my diabetes is mild and controlled by diet? 

Yes. The risk is slightly less in diet-controlled diabetes.

Are eye checks needed if my diabetes control is very good?

Yes, the risk is much less, but other factors can influence retinopathy development, so eye checks are still needed.

Is fluctuating vision a sign of developing retinopathy? 

Yes, vision changes can be due to retinopathy or due to fluctuating (high) blood glucose affecting the lens of your eye. However, there are other possible causes such as the onset of presbyopia (the need to wear glasses for close work) which usually starts to occur from your mid-40s onwards.

Can I tell if my diabetes is affecting my eyes?

In early retinopathy there are no symptoms. Visual acuity (how well you can read an eye chart) is normal (unless cataract or other eye problems have developed). This is why you need to have regular retinal examinations.

Is there any point in controlling my diabetes if I already have retinopathy? 

Yes, there is! There is strong evidence that progression of retinopathy can be slowed by about 50% in many people with mild or moderate disease. However, retinopathy is not slowed by improved blood glucose control when it is advanced, but your response to laser treatment may be better.

Is laser treatment painful?

Most people who have macula treatment do not experience pain. If you need treatment to the peripheral retina, this may cause mild pain and a dull ache for a few hours following treatment. The ophthalmologist (eye specialist) will talk with you about what can be done to minimise this as much as possible.

Does laser treatment cause blindness?

No. If your diagnosis is too late, then the damage has already occurred. In these cases, laser treatment may still be offered in an attempt to retain some sight.

Like most treatments, laser treatment can have complications. In some advanced proliferative cases, bleeding into the vitreous may occur and/or retinal detachment. However, such complications would have occurred without treatment. It still means your eye is in a better state if you need surgery to remove blood from inside your eye and re-attach the retina.

Ask your eye doctor what the risks and benefits of all treatment options are for you.

How soon will I notice the benefits of laser treatment?

Laser is extremely effective in most people, but benefits may not occur for some months. Vision may improve for a long time as the retinopathy stabilises.

After laser treatment is finished, will it need to be repeated each year?

If you have macular disease, treatment may need to be repeated if the disease remains active and recurs in new areas of the macula.

If you have proliferative disease, further treatment is rarely needed once all the abnormal blood vessels have gone.

Video: 4B Diabetes - Looking after your eyes

If you have diabetes, it is very important to keep your blood sugars down to protect your eyes. It's a good idea to have your diabetic eye check (known as a retinal screen) every one to two years as recommended by your healthcare team. This video may take a few moments to load.

(Health Navigator Charitable Trust and Synergy Film, NZ, 2014)

Clinical guidelines and resources

Best Practice diabetes toolbox(external link) BPAC, NZ, 2021
Management of diabetic retinopathy(external link) NZ Society for the Study of Diabetes and Ministry of Health, NZ, 2021
Type 2 diabetes management guidance(external link) NZ Society for the Study of Diabetes and Ministry of Health, NZ, 2021
Management of type 2 diabetes(external link) NZ Primary Care Handbook, pages 45-64, including:

• glycaemic control
• management of blood pressure
• preventing complications
• starting insulin.

Prevalence of diabetic retinopathy at first presentation to the retinal screening service in the greater Wellington region of New Zealand 2006–2015, and implications for models of retinal screening(external link) NZMJ, 2017
Diabetic retinal screening, grading, monitoring and referral guidance(external link) Ministry of Health NZ, 2016
Screening for diabetic retinopathy in primary care(external link) BPAC NZ, 2010

See our page Diabetes for healthcare providers

Continuing professional development

Video: Diabetic retinopathy: management and developments

This video may take a few moments to load.

(Goodfellow Unit Webinar, NZ, 2018)

Apps

Diabetes apps
Visual impairment apps