What are the stages of diabetic retinopathy?
Having elevated blood sugar levels over long periods of time can pose a threat to our eyesight. High blood glucose levels in people with diabetes cause the blood vessels in the retina to become ‘leaky’, which causes haemorrhaging of blood and fluids. This causes our vision to become distorted. In advanced stages of the condition, there is an increase in the number of new, abnormal blood vessels. These new blood vessels are fragile and can cause scarring of the retinal surface, leading to further complications. The stages of diabetic retinopathy are categorised in many different ways, but put simply they are:
No retinopathy — No changes are detected. Return in a year for another test.
Background retinopathy (also known as mild non-proliferative diabetic retinopathy) — Small changes are detected, but your eyesight is not affected. Follow your doctor’s recommendations to prevent further eye damage. Return in one year for another screening.
Referable retinopathy (also known as non-proliferative diabetic retinopathy) — Diabetes has caused damage to the eyes (categorised as moderate or severe) and your vision may be affected . You will be referred to a specialist for further advice. Screening tests may be required more often than annually, and you may need to start treatment for your eye damage.
Proliferative retinopathy – the most advanced form of DR and the point at which vision can be lost as the eye makes new, albeit weaker, blood vessels to compensate for damage vessels.
Certain factors can increase or decrease the risk of developing diabetic eye disease and of progressing to more severe stages of the condition. These modifiable factors include3, 4:
- 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 age 13 or older
- Pregnancy — there is a higher incidence in pregnant women with type 1 diabetes
Background retinopathy/mild non-proliferative diabetic retinopathy
This is the earliest stage of diabetic retinopathy – ‘non-proliferative’ means that the eye is not making new blood vessels, a process known as ‘proliferation’. The blood vessels are weakened and there are one or more microaneurysms present — tiny balloon-like bulges in the vessel walls from where blood and fluid leak into the retina. The changes are subtle and at this stage, carry no threat to your vision.
Because symptoms are either mild or non-existent at this stage2, people with diabetes are advised to undergo yearly eye checks. This check is called a diabetic retinopathy screening, where your eyes will be dilated and imaged (known as digital retinal photography). This will reveal any changes in the retina.
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 deteriorating3.
A yearly follow-up is usually recommended for people with background DR. However, you may need to go back sooner if you have tested negative for DR 5, to monitor for any signs of the condition.
Referable retinopathy/ moderate non-proliferative diabetic retinopathy (NPDR)
As DR progresses, blood vessels that bring nourishing blood to the retina swell and distort2. These vessels are blocked from transporting blood normally, resulting in hypoxia (lack of oxygen), while multiple microaneurysms (tiny swellings) are present in the walls of the blood vessels. When these microaneurysms rupture, it causes haemorrhages. Fluid may then begin collecting in the macula, which is the central area of the retina. This complication is known as ‘diabetic macular oedema’6.
The macula is responsible for ensuring our vision is ‘sharp’: that we can see and read in great detail and have the best possible colour vision. Macular oedema may cause blurred vision. Other symptoms of moderate non-proliferative retinopathy can include floaters (spots or strings in our vision), dark areas in our vision, problems differentiating colours, and vision that fluctuates in quality7.
Specific treatment is usually not necessary for non-proliferative diabetic retinopathy8. At this stage of the disease, controlling modifiable risk factors is recommended to prevent further damage from occurring.
The UK Prospective Diabetes Study revealed that improved blood sugar control and improved blood pressure control can significantly reduce the risk of retinopathy.
Regular monitoring with dilated eye examinations is very important, because early diagnosis and treatment can help prevent blindness in over 90% of cases9.
Severe non-proliferative diabetic retinopathy
This stage represents the most severe form of NPDR. It is characterised by the presence of cotton wool spots on the retina due to damage of the nerve fibres. These are severe abnormalities in the retina vessels that appear as fluffy white patches on the retina.
At this stage, more blood vessels are blocked, depriving extensive areas of the retina of blood and oxygen. Microaneurysms are present in all four quadrants of the eye, which are sections of the eye that each work to interpret what you see within your total field of vision. Venous beading also occurs, which is where the veins in the eye appear like strings of sausages.
Approximately 50 percent of people with severe non-proliferative diabetic retinopathy will progress to proliferative diabetic retinopathy within one year, if the disease takes its natural course4. People at this stage of diabetic retinopathy may require dilated eye examinations as often as every two to four months2.
- Diabetes.co.uk (no date). Diabetic Retinopathy. [Online]. Available at: https://www.diabetes.co.uk/diabetes-complications/diabetic-retinopathy.html [Accessed 21 August 2019].
- National Eye Institute. (no date). Facts About Diabetic Eye Disease. [Online]. Available at: https://nei.nih.gov/health/diabetic/retinopathy [Accessed 21 August 2019].
- Fong DS, Aiello L, Gardner TW, King GL, Blankenship G, Cavallerano JD, Ferris FL, Klein R. Diabetic Retinopathy. American Diabetes AssociationDiabetes Care. Jan 2003, 26 (suppl 1) s99-s102. [Online]. Available at: https://care.diabetesjournals.org/content/26/suppl_1/s99. [Accessed 21 August 2019].
- Singh R, Ramasamy K, Abraham C, Gupta V, 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].
- 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].
- University of Iowa Healthcare. (no date). Diabetic Retinopathy – From One Medical Student to Another. [Online]. Available at: https://webeye.ophth.uiowa.edu/eyeforum/tutorials/Diabetic-Retinopathy-Med-Students/Classification.htm [Accessed 21 August 2019].
- Mayo Clinic. (no date). Diabetic Retinopathy. [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/diabetic-retinopathy/symptoms-causes/syc-20371611#targetText=Diabetic%20retinopathy%20(die-uh-,or%20only%20mild%20vision%20problems. [Accessed 21 August 2019].
- NHS Diabetic Retinopathy. (no date). Treatment. [Online]. Available at: https://www.nhs.uk/conditions/diabetic-retinopathy/treatment/# [Accessed 21 August 2019]
- 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].