What is diabetic retinopathy?
If you have diabetes, you’re at risk of developing diabetic retinopathy, a complication of diabetes that damages the light-sensitive layer at the back of the eye called the retina. This occurs because the retina is supplied with blood by a delicate network of blood vessels, and diabetes can cause the blood vessels to become blocked or start leaking. If the retina is not receiving a good blood supply, it can’t work properly.
If left undiagnosed and untreated, diabetic retinopathy can lead to significant vision impairment. Thankfully, with ongoing diabetes management and regular screening, you can protect your vision and reduce the likelihood of visual complications occurring.
Diabetic retinopathy stages
The stages of diabetic retinopathy can be explained in various ways, depending on who you speak to. At Specsavers, we break them down into the following four stages, which cover the level of damage to the retina’s blood vessels:
(Also known as mild non-proliferative diabetic retinopathy, or NPDR). At the earliest stage of diabetic retinopathy, we can detect small changes to your blood vessels, usually seen as tiny bulges in the walls of the blood vessels supplying the backs of your eyes. These can also bleed easily due to the weakening of the blood vessel walls, so some small haemorrhages may be detected. Your eyesight isn’t usually affected at this stage, so no specific treatment is recommended for background retinopathy. However, diligent blood sugar control can prevent the condition from progressing. Also, keeping your blood pressure within the target range (with lifestyle changes or medications, if necessary) can delay or prevent the progression of retinopathy and reduce the risk of vision deteriorating.1 A yearly follow-up is usually recommended for people with background DR. If you have tested negative for DR,2 you may need to go back sooner to monitor for any signs of the condition. Your optometrist will advise on when your next examination should be.
Pre-proliferative diabetic retinopathy
(Also known as referable retinopathy) — we can see more severe and more widespread damage to the blood supply of the retina and there is a higher risk that your eyesight could be affected. You may at this stage be referred to a diabetic eye clinic to decide how to reduce any further deterioration to the blood supply.
Specific treatment is usually not necessary for non-proliferative diabetic retinopathy.3 At this stage of the disease, controlling modifiable risk factors is recommended to prevent further damage from occurring. Regular monitoring with dilated eye examinations is very important because early diagnosis and treatment can help prevent blindness in over 90% of cases.4
Proliferative diabetic retinopathy (PDR)
This is where, as a result of the poor blood supply at the back of the eyes, new vessels have formed to try and compensate for the reduced blood flow in the usual retinal blood vessel network. These new vessels are fragile and can bleed significantly, and there may also be scar tissue forming on the retina that can lead to more serious sight-threatening problems such as retinal detachments. At this point, there is a very high risk you could lose your eyesight, and referral for potential treatment will be offered to try and stabilise your vision. At this stage, any vision which has already been lost is unlikely to be restored.
The vessels supplying the central part of the retina, which is responsible for our central vision and seeing fine detail, become blocked or leak fluids, fats and proteins. At this point, there is a significant chance your eyesight will be affected, and it can impact your ability to read or see fine detail. Referral to a diabetic eye specialist is necessary for further monitoring and to determine if any treatment is required.
Diabetic retinopathy causes
The retina is the light-sensitive layer that covers the backs of our eyes, and it needs a constant supply of blood to keep it healthy. Diabetic retinopathy occurs when high blood sugar levels start to damage these blood vessels. The damage happens in three main stages (background, pre-proliferative and proliferative), all of which can be accompanied by diabetic maculopathy. It’s in the advanced stages that the vessels become weaker and blood can leak out, causing complications that can lead to vision loss.
Diabetic retinopathy and diabetic macular oedema
Diabetic retinopathy (DR) and diabetic macular oedema (DMO) are both eye conditions that can affect people with diabetes.
Diabetic macular oedema may develop as a result of the damage to blood vessels in diabetic retinopathy, which can cause fluid to accumulate in the macula. The macula is the part of the retina responsible for making sure our vision is clear and sharp. If left untreated, either condition can potentially lead to severe vision loss and blindness.
Is diabetic macular oedema the same as diabetic retinopathy?
No, but the two conditions are closely linked. Diabetic retinopathy is a common cause of diabetic macular oedema, and DMO is the most common cause of vision loss in people who have DR. Macular oedema typically develops as retinopathy worsens, but it can occur at any stage of DR. Not everyone with diabetic retinopathy will necessarily develop diabetic macular oedema, however. Experts estimate that around 10% of people with DR also have DMO.5
Diabetic retinopathy risk factors
Certain factors can increase or decrease the risk of developing diabetic eye disease and of progressing to more severe stages of the condition. These risk factors include:6, 7
- Blood sugar control — managing your blood glucose levels can significantly reduce the risk of retinopathy
- Blood pressure control — keeping your blood pressure at a healthy level reduces the risk of the condition progressing, and of vision deteriorating
- Serum cholesterol level — treatment with lipid-lowering drugs can reduce the severity of retinal changes
- Frequent eye examinations — these help in detecting retinopathy and determining when to initiate treatment. More frequent eye examinations are necessary for people with moderate to severe DR
Other risk factors for developing diabetic retinopathy include:
- Duration of diabetes — retinopathy is more likely to develop and progress in people who have had diabetes for a decade or more
- Age — there is an increased incidence of DR with increasing age in people with Type 1 diabetes
- Anaemia — low haemoglobin levels (proteins in the blood responsible for transporting oxygen) increase the risk of retinopathy
- Puberty — there is an increased risk in people who are diagnosed with diabetes at the age of 13 or older
- Pregnancy — there is a higher incidence of retinopathy in pregnant women with Type 1 diabetes
Diagnosis of diabetic eye complications
If you have diabetes and are wondering whether it has affected your eye health, a visit to the optometrist can help you identify any issues and make a plan for managing them. Some of the tests that may be performed include:
- Visual acuity testing with an eye chart
- Tonometry to measure the pressure inside the eye
- Dilated eye exam to examine the optic nerve and retina
- Digital retinal photography
- OCT (optical coherence tomography) to capture 3D images of the eye
These tests will show any changes in the retinal blood vessels that indicate damage due to diabetes. If intermediate or advanced stages of DR or DMO are discovered, more frequent dilated eye examinations may be recommended, and treatment may be started.
Laser treatment for diabetic retinopathy
Stage 3 diabetic retinopathy is associated with proliferation (rapid growth) of new blood vessels in the retina. These new blood vessels are considered ‘abnormal’ and may cause bleeding in the eye and lead to increased vision problems.
Laser treatment can stabilise these changes and prevent further deterioration in vision, although eyesight is unlikely to improve. There are two main types of laser treatments for diabetic eye disease:
- Focal laser photocoagulation — the laser is applied in a grid-like pattern to a specific affected area
- Pan retinal photocoagulation — the laser is applied to the more peripheral retina without touching the central area
How is laser treatment performed?
The treatment is performed at an outpatient laser treatment centre under local anaesthesia, which works to numb the eyes. The procedure is not painful for most people, but the treatment of certain areas in the eye may produce a sharp pricking sensation. The pupils are first widened with eye drops, and then the eyelids are held open with special contact lenses. The laser is then aimed precisely at the retina. The entire process takes around 20-40 minutes, and it is usually possible to go home the same day. However, more than one session may be required.
Laser treatment side effects
Your vision will be blurry for several hours after the procedure, so it’s important to have someone to drive you home. You are also likely to have an increased sensitivity to light, so it’s a good idea to bring sunglasses for your journey home. An over-the-counter painkiller, such as paracetamol, is usually sufficient to take care of any mild discomfort or aching. It can take several months to find out if the treatment is helping. Some of the possible complications of the procedure include floaters, blind spots in vision, reduced night vision, and having the laser pattern imprinted temporarily in the eye.10 The laser photocoagulation procedure is largely safe and effective and can reduce the risk of blindness by more than half in people with extensive amounts of new blood vessels on or near where the optic nerve meets the retina.11
Eye injections for diabetic maculopathy
Injections given directly into the eyes are called anti-VEGF (‘vascular endothelial growth factor’) agents. These inhibit the formation of abnormal blood vessels in the retina, stopping diabetic eye disease from worsening. It may even improve vision. Sometimes steroids are injected instead of anti-VEGF agents, but this comes with a risk of increased pressure inside the eyes.
How is the injection administered?
Before the injection is administered, the skin around the area is cleaned. Then local anaesthetic drops are used to numb the eyes, and small clips are used to keep the eyelids open. The injection is then given with a very fine needle. Initially, the treatment is typically given once a month, but as your vision begins to stabilise, the injections may be given less often or even stopped altogether.
Eye injection side effects
Possible side effects of the injection include floaters, bleeding, irritation, discomfort, and watery or itchy eyes.10 Overall, however, these drugs are safe and effective: studies show that nearly 40% of eyes injected with ranibizumab show an improvement in retinopathy.12 The drugs can also slow the progression of the disease, and studies show that aflibercept is better at improving vision compared to laser treatment.12
Eye surgery for vitreous haemorrhage
Behind the lens in the eye, there is a jelly-like substance called the vitreous humour, which can be removed surgically if a haemorrhage (bleeding) does not clear and a large collection of blood remains in the eye. This procedure is called a vitrectomy or vitreoretinal surgery and is also advisable for people with extensive scarring that poses a risk of, or has already caused, the retinal detachment.
How is the surgery performed
The surgery is usually done under local anaesthesia and sedation. The surgeon will make a small incision in the eye, and then remove the vitreous humour and scar tissue with a laser. You will normally be discharged from the hospital on the same day or the day after the surgery and will be given a patch to wear over the treated eye for a few days. This can make reading and watching TV difficult, and your ‘seeing’ eye may tire easily. After the operation, your vision will be blurry and may take several months to return to normal.
Eye surgery side effects
Possible side effects of the surgery include further bleeding, retinal detachment, infection, cataract formation, and build-up of fluid in front of the eye.10 Vitreoretinal surgery has been shown to improve or stabilise vision in over 85% of patients and is considered both safe and effective.13
1. Fong, DS., Aiello, L., Gardner, TW., King, GL., Blankenship, G., Cavallerano, JD., Ferris, FL. and Klein, R. Diabetic Retinopathy. American Diabetes Association Diabetes Care. Jan 2003, 26 (suppl 1) s99-s102. [Online]. Available at: https://care.diabetesjournals.org/content/26/suppl_1/s99. [Accessed 21 August 2019].
2. American College of Physicians. (no date). Diabetic Retinopathy (Non-Proliferative, Very Mild). [Online]. Available at: https://www.acponline.org/meetings-courses/internal-medicine-meeting/ophthalmology-self-guided-study-activity-herbert-s-waxman-clinical-skills-center/diabetic-retinopathy-non-proliferative-very-mild [Accessed 21 August 2019].
3. NHS Diabetic Retinopathy. (no date). Treatment. [Online]. Available at: https://www.nhs.uk/conditions/diabetic-retinopathy/treatment/# [Accessed 21 August 2019].
4. Medscape. (Updated 22 May 2019). Diabetic Retinopathy Treatment and Management. [Online]. Available at: https://emedicine.medscape.com/article/1225122-treatment#d1 [Accessed 21 August 2019].
5. National Eye Institute. (no date). Facts About Macular Edema. [Online]. Available at: https://nei.nih.gov/health/macular-edema/fact_sheet [Accessed 20 August 2019].
6. Fong, DS., Aiello, L., Gardner, TW., King, GL., Blankenship, G., Cavallerano, JD., Ferris, FL. and Klein, R. Diabetic Retinopathy. American Diabetes Association Diabetes Care. Jan 2003, 26 (suppl 1) s99-s102. [Online]. Available at: https://care.diabetesjournals.org/content/26/suppl_1/s99. [Accessed 21 August 2019].
7. Singh, R., Ramasamy, K., Abraham, C., Gupta, V. and Gupta, A. Diabetic retinopathy: an update. Indian J Ophthalmol. 2008;56(3):178–188. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2636123/ [Accessed 21 August 2019].
8. Diabetes.co.uk. (no date). Diabetic Retinopathy Screening and Tests. [Online]. Available at: https://www.diabetes.co.uk/diabetes-complications/retinopathy-screening.html [Accessed 20 August 2019].
9. Garg, S. and Davis, RM. (2009). Diabetic Retinopathy Screening Update. American Diabetes Association Clinical Diabetes. 2009 Oct; 27(4): 140-145. [Online]. Available at: https://clinical.diabetesjournals.org/content/27/4/140 [Accessed 21 August 2019].
10. NHS Diabetic Retinopathy. (no date). Treatment. [Online]. Available at: https://www.nhs.uk/conditions/diabetic-retinopathy/treatment/# [Accessed 21 August 2019].
11. No authors listed. Preliminary Report on The Effects of Photocoagulation Therapy. The Diabetic Retinopathy Study Group. Am J Ophthamol. 1976 Apr. [Online]. Available at: https://nei.nih.gov/news/pressreleases/drspressrelease [Accessed 21 August 2019].
12. Zhao, Y. and Singh, RP. The role of anti-vascular endothelial growth factor (anti-VEGF) in the management of proliferative diabetic retinopathy. Drugs Context. 2018;7:212532. Published 2018 Aug 13. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6113746/ [Accessed 21 August 2019].
13. Brănişteanu, DC., Bilha, A. and Moraru, A. Vitrectomy surgery of diabetic retinopathy complications. Rom J Ophthalmol. 2016;60(1):31–36. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5712917/ [Accessed 21 August 2019].