Diabetic retinopathy is one of the world’s leading causes of vision loss in working age, and it is almost always the result of diabetes that has continued for years. At the same time it is one of the diseases where good control, an annual exam and timely treatment change the outcome almost completely. This page explains what happens in the retina, how the disease progresses, and how it is treated. For the separate matter of disability percentages — an entirely different subject — see diabetic retinopathy and disability percentages.
What happens in the retina
The retina is the layer of tissue at the back of the eye that captures light, and it is nourished by a dense network of tiny blood vessels. High blood sugar over time damages the walls of these vessels: they become permeable and begin to leak fluid and blood, and some close off, leaving areas of the retina without blood supply. The oxygen-starved retina releases signals that encourage the growth of new blood vessels — but these are fragile, grow in the wrong places, and tend to bleed. These two processes — the leakage and the closure — are the basis of all the damage.
The stages
Non-proliferative retinopathy (NPDR) is the early stage: microaneurysms in the vessels, small haemorrhages, fatty deposits (exudates) and “cotton-wool” spots that mark areas without blood. It is graded from mild to severe by the extent of the findings.
Proliferative retinopathy (PDR) is the advanced stage, in which new, fragile vessels are already growing. Here the real risk of severe vision loss appears: bleeding into the vitreous, and tractional retinal detachment as scar tissue pulls the retina from its place.
Diabetic macular edema (DME) is an accumulation of fluid at the centre of vision (the macula), and it is the most common cause of reduced vision in diabetic retinopathy. It is important to know that it can appear at any stage — even in mild retinopathy — so the severity of the stage alone cannot be relied on.
Why an annual exam is critical
The dangerous point in diabetic retinopathy is that it is silent: vision stays normal until the damage is already extensive, sometimes until there is already bleeding or central swelling. One cannot feel vessels leaking or closing. The main tool is therefore not the symptom but the proactive exam:
- In type 2 diabetes — a dilated eye exam from the moment of diagnosis, then annually.
- In type 1 diabetes — from five years after diagnosis, then annually.
- In pregnancy in a diabetic woman — closer monitoring, because the disease can worsen rapidly.
Anyone who already has findings is examined more frequently, according to severity.
How it is diagnosed
- A dilated fundus exam — the foundation, for assessing the vessels, the haemorrhages and any new vessels.
- OCT imaging — a cross-section of the macula that identifies and measures central swelling with great precision, and also tracks the response to treatment.
- Fundus photography for documentation and comparison over time.
- Angiography (FA or OCT-A) — showing where there is leakage and where there are areas without blood, and helping to plan laser.
Treatment
The foundation: metabolic control. Control of blood sugar, blood pressure and blood lipids slows the progression of the disease more than any ocular intervention, and it is always the first line. An important note: an overly sharp, rapid fall in blood sugar can in fact temporarily worsen the retinopathy, so control should be measured.
Anti-VEGF injections. In macular edema affecting the centre of vision, anti-VEGF injections into the eye are the standard treatment — they reduce the leakage, and can even improve the grade of the retinopathy itself. They are given in a series and require regular follow-up.
Laser. Focal laser treats local leakage, and scatter laser (PRP) in proliferative retinopathy stabilises the retina and demonstrably reduces the risk of severe vision loss. PRP has the advantage of a lasting effect, so it is sometimes preferred for patients who find it hard to attend regular follow-up. On the price of laser in the peripheral field, see visual field loss.
Surgery (vitrectomy). Reserved for advanced cases — a vitreous haemorrhage that does not clear or a tractional retinal detachment.
One of the severe complications of untreated proliferative disease is neovascular glaucoma, in which new vessels block the eye’s drainage; the background to this is explained in glaucoma.
Bottom line
Diabetic retinopathy develops silently, so good vision is no guarantee of a healthy retina. But it is also a disease in which good metabolic control, an annual eye exam and modern treatment — anti-VEGF injections and laser — halt the disease in most cases and prevent the loss of vision. The most important thing is simple: anyone with diabetes should be examined every year, even when vision is excellent. On how the disease is rated by disability committees, see diabetic retinopathy and disability percentages. For an overview of other eye diseases, see eye diseases.
The information on this page is general and not a substitute for a personal examination and medical advice. Anyone with diabetes is welcome to arrange a dilated eye exam with an ophthalmologist.
Frequently asked questions
What is diabetic retinopathy?
Diabetic retinopathy is damage to the small blood vessels of the retina, caused by high blood sugar levels over time. The damaged vessels leak fluid and blood, and at advanced stages they close and cause a lack of oxygen, which triggers the growth of new, fragile vessels. It is one of the leading causes of vision loss in working age — but also one that can, in most cases, be prevented or halted through control and monitoring.
I have diabetes but I see well. Do I still need an eye exam?
Yes, and this is the most important point. Diabetic retinopathy develops silently — vision stays normal until the damage is already significant. The recommendation is therefore an annual dilated eye exam: in type 2 diabetes from the moment of diagnosis, and in type 1 diabetes from five years after diagnosis. Waiting for symptoms usually means a delay in treatment.
How is diabetic retinopathy treated?
The foundation is control of blood sugar, blood pressure and blood lipids — this slows the disease more than any eye treatment. When there is swelling at the centre of vision, the standard treatment is anti-VEGF injections into the eye, which reduce the leakage. In proliferative disease, scatter laser (PRP) is used to stabilise the retina, and sometimes injections. In advanced cases with bleeding or detachment — vitrectomy surgery.
Does diabetic retinopathy cause blindness?
It can, if left untreated — through bleeding into the vitreous, tractional retinal detachment, or neovascular glaucoma. But with early detection and modern treatment, most cases can be stabilised, and the risk of severe vision loss has fallen significantly. The key is to catch the disease before it reaches these stages — which is why the annual exam matters so much.
