Diabetes Related Sight Loss

Diabetes is a chronic disease which develops when there is too much glucose (sugar) in the blood (hyperglycaemia). This occurs because either the pancreas does not produce sufficient amounts of insulin or because the insulin cannot be used properly by the body. There are three main forms of diabetes:

 

Type-1 diabetes: Type-1 diabetes is most common in young children and adolescents, arising when the body’s b-cells which produce insulin, are attacked by the body’s immune system. People living with type-1 diabetes often take insulin injections, which is why type-1 diabetes is also known as insulin-dependent diabetes. Low blood-sugar level (hypoglycaemia) is a common feature of type-1 diabetes, as physical activity, meal timing and alcohol can influence how much insulin is required by the body. When too much insulin is present, blood-sugar levels can drop very low and may result in headaches, hunger, feeling of weakness and cold sweats.

Type-2 diabetes: Type-2 diabetes develops because the insulin produced by the pancreas either fails to enter the bloodstream in sufficient amounts or does not work properly because the body has become insulin-resistant. Type-2 diabetes is most common in people who live a very sedentary lifestyle and is associated with bad food habits and obesity.

Gestational Diabetes: Gestational diabetes is most often a temporary condition during pregnancy when the body becomes resistant to insulin due to hormone production within the placenta. However, if you already live with diabetes or a diabetes-related eye condition, you are more likely to experience your condition to progress more quickly than normal.

Diabetes-related Eye Diseases (DEDs) develop as a direct result of chronic high blood-glucose levels which impacts the signalling networks within the eye. The spectrum of DEDs includes Diabetes-related Retinopathy, Diabetes-related Macular Edema, Diabetes-related Cataract, Diabetes-related Glaucoma, Diabetes-related Uveitis, Diabetes-related Keratopathy, and Diabetes-related Dry Eye Syndrome. It is very important to be aware that these conditions are not mutually exclusive and that it is possible to develop one or more of these diabetes-related retinal diseases.

What are the Symptoms of DEDs?

Diabetes-related Retinopathy is the most common form of DED among adults, affecting 93 million people worldwide and exists in two forms;  non-proliferative Diabetes-related Retinopathy and proliferative Diabetes-related Retinopathy1.

Non-proliferative Diabetes-related Retinopathy (NPDR) is the early form, where high glucose levels in the bloodstream causes blockages to develop in blood-vessels within the eye, resulting in some leakage. Blood-vessels do not burst in this early stage, explaining why it is called non-proliferative Diabetes-related Retinopathy. Early nonprolifeative Diabetes-related Retinopathy is generally asymptomatic and detected by dilated eye examinations. Diagnosing Diabetes-related Retinopathy in its early stages allows for the condition to be well managed and prevent further complications from developing, while also allowing for any damage to be reversed in certain cases.

The advanced stage of Diabetes-related Retinopathy is called proliferative Diabetes-related Retinopathy. In this stage, new and immature blood-vessels grow in an effort to compensate for the damaged blood-vessels. However, these blood-vessels are weaker and more susceptible to bursting. When they burst, blood leaks into the vitreous cavity (vitreous haemorrhage) and is responsible for “floaters” or “spots” in our visual field, two common symptoms of proliferative Diabetes-related Retinopathy.

Although vitreous haemorrhage does not cause permanent vision loss by itself, the formation of scar tissue by the leaking blood vessels can cause retinal detachment and often damages the optic nerve; the nerve which delivers visual information from the eye to the brain.

When blood leaks and accumulates in the central region of the retina, called the macula, this is called Diabetes-related Macular Edema (DME). In this instance, the macula swells with blood to cause blurred and distorted vision.

A more detailed description of the causes and symptoms of Diabetes-related Eye Diseases is available in the DED resource.

What treatments are available?

Like with all diseases, prevention is better than treatment. Maintaining consistent blood-glucose levels and having regular eye exams play a key role in managing diabetes and reducing the possibility of eye complications.

Laser surgery called panretinal photocoagulation is a very reliable and proven way to reduce the risk of vision loss from Diabetes-related Macular Edema as it prevents the blood vessels from leaking, or can get rid of the growth of abnormal, fragile vessels as necessary. Anti-vascular endothelial growth factor (anti-VEGF) is another extremely common therapy option which inhibits VEGF activity. VEGF is overactive in people with Diabetes-related Macular Edema and proliferative Diabetes-related Retinopathy, causing unregulated immature blood-vessel growth. There are a number of anti-VEGF therapies available for use and are administered via intravitreal injection into the back of the eye.

Corticosteroids are another drug therapy along with anti-VEGF which help to treat Diabetes-related Macular Edema and Diabetes-related Retinopathy. Corticosteroids act by preventing inflammation, which is associated with their onset.

Vitreoretinal surgery (Vitrectomy) is an invasive treatment strategy for proliferative Diabetes-related Retinopathy, when blood leaks into the vitreous and does not clear by itself. It is particularly helpful for treating Diabetes-related Macular Edema, when there is retinal thickening and helps to avoid retinal detachment.

More information specific to the causes, symptoms and treatment options for each DED is available to read in the DED resource.

References

1. IAPB Vion Atlas. Diabetic Retinopathy. http://atlas.iapb.org/vision-trends/diabetic-retinopathy/ last accessed April 2020.

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