DIABETIC EYE DISEASE
How Does Diabetes Affect the Eyes?
Diabetes affects the small blood vessels throughout the body, including those supplying the retina, the light-sensitive layer at the back of the eye.
Over time, persistently high blood sugar levels can damage these blood vessels, leading to a group of conditions collectively known as diabetic eye disease, the most significant of which is diabetic retinopathy.
A key feature of diabetic retinopathy is that it is often asymptomatic in its early stages. Significant damage to the retina can occur before any change in vision is noticed, which is why regular eye screening for everyone with diabetes, regardless of whether vision feels normal, is one of the most important aspects of diabetes care.
Diabetic Eye Disease (Diabetic Retinopathy) in Singapore
Stages of Diabetic Retinopathy
Diabetic retinopathy progresses through recognised stages, which guide monitoring intervals and treatment decisions:
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Mild non-proliferative diabetic retinopathy: early changes, such as small areas of swelling in the blood vessels (microaneurysms), are visible on examination.​
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Moderate to severe non-proliferative diabetic retinopathy: more widespread changes occur, including blocked blood vessels, which can begin to affect the blood supply to areas of the retina.​
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Proliferative diabetic retinopathy: the most advanced stage, where the retina, lacking adequate blood supply, signals the growth of new, abnormal blood vessels. These new vessels are fragile and can bleed into the eye (vitreous haemorrhage) or lead to scar tissue formation, which can pull on the retina and cause a tractional retinal detachment.
Diabetic Macular Oedema (DMO)
Diabetic macular oedema is a separate but related condition that can occur at any stage of diabetic retinopathy.
It happens when damaged blood vessels leak fluid into the macula, the central part of the retina responsible for sharp vision, causing it to swell.
DMO is one of the most common causes of vision impairment in people with diabetes and can occur even when the overall level of diabetic retinopathy is relatively mild.
Symptoms of Diabetic Eye Disease
In the early stages, there are often no symptoms at all. As the condition progresses, symptoms may include:
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Blurred or fluctuating vision, sometimes varying with blood sugar control.
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Dark spots or floaters, particularly if there has been bleeding into the vitreous.
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Patchy or distorted central vision, often related to diabetic macular oedema.
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Difficulty seeing at night.
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A sudden, significant loss of vision, which can occur with vitreous haemorrhage or tractional retinal detachment in advanced proliferative disease.
Because early diabetic retinopathy is typically silent, the absence of symptoms should never be taken as reassurance that screening is unnecessary.
Who is at Risk, and How Often Should Screening Occur?
All individuals with type 1 or type 2 diabetes are at risk of diabetic retinopathy, with risk increasing according to:
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Duration of diabetes: longer duration is associated with higher risk.
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Blood sugar control: higher long-term blood sugar levels (HbA1c) are associated with greater risk and faster progression.
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Blood pressure and cholesterol control: poorly controlled hypertension and lipid levels can worsen diabetic retinopathy.
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Pregnancy: diabetic retinopathy can progress more rapidly during pregnancy in women with pre-existing diabetes.
Screening intervals depend on the presence and severity of any retinopathy found, and are determined individually, ranging from annual screening for those with no or minimal retinopathy, to much more frequent monitoring for those with more advanced disease or active treatment.
How is Diabetic Eye Disease Diagnosed and Monitored?
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Dilated fundus examination, to directly assess the retina for signs of diabetic retinopathy.
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Retinal photography, to document findings and track changes between visits.
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Optical coherence tomography (OCT): used to detect and measure diabetic macular oedema with high precision, and to monitor response to treatment.
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Fluorescein angiography or OCT angiography: may be used to assess blood flow within the retina and identify areas of poor perfusion, particularly in more advanced disease.
Treatment of Diabetic Eye Disease
Treatment depends on the stage of diabetic retinopathy and whether diabetic macular oedema is present.
Laser Photocoagulation
For diabetic macular oedema, the primary treatment is intravitreal injection of medication directly into the eye. Two main categories of medication are used:
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Anti-VEGF medications, which target the abnormal signalling that causes blood vessel leakage and swelling, and are typically used as first-line treatment.
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Intravitreal steroid implants, which reduce inflammation and swelling within the eye, and may be considered in certain cases, including when anti-VEGF treatment has not been sufficiently effective.
For proliferative diabetic retinopathy, anti-VEGF injections can also be used to help regress abnormal blood vessel growth, often alongside laser treatment.
Laser Treatment (Panretinal Photocoagulation)
For proliferative diabetic retinopathy, panretinal photocoagulation (PRP) uses laser to treat areas of the peripheral retina that have an inadequate blood supply. This reduces the signal driving abnormal blood vessel growth, helping to stabilise the condition and reduce the risk of bleeding or tractional retinal detachment.
Vitrectomy Surgery
In more advanced cases, vitrectomy may be required to:
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Remove blood from the vitreous cavity (vitreous haemorrhage) that has not cleared on its own.
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Relieve traction from scar tissue and repair a tractional retinal detachment.
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Address other complications of advanced proliferative diabetic retinopathy
Why Regular Screening Matters
Because diabetic retinopathy and diabetic macular oedema can develop and progress silently, regular screening allows treatment to begin before significant vision loss occurs.
Early-stage disease is generally easier to manage and is associated with better outcomes than advanced disease, where treatment focuses more on preventing further deterioration and managing complications such as vitreous haemorrhage or tractional retinal detachment.
FAQ
Frequently Asked Questions
