How diabetes affects your sight
Diabetes mellitus (often shortened to diabetes) occurs when the body doesn’t produce enough insulin, or when the produced insulin is less effective than normal. The condition is lifelong, and affects over 3 million people aged 16 or over in England.
The term ‘diabetes’ can refer to two main types of the disease:
- Type 1 diabetes – This type of diabetes is caused by the body producing no or very little insulin. Primarily controlled by insulin injections, this type makes up around 10% of all diabetes cases.
- Type 2 diabetes – This type of diabetes is caused by the body not being able to use the produced insulin properly, or not producing enough.
Primarily controlled by diet, lifestyle changes, tablets and occasionally insulin injections, this type makes up around 90% of all diabetes cases. Diabetes can affect many of the body’s major organs, often significantly reducing their effectiveness. The heart, kidneys, skin and nervous system are all negatively impacted by both types of diabetes.
Diabetic retinopathy is a complication that can affect people with diabetes, and is the most common cause of blindness among working age people in the UK.
The small blood vessels in the eye can be affected as a result of diabetes. They may become blocked or start to leak, which can affect vision.
Diabetic retinopathy can get worse over time, and has different stages of severity:
- Background retinopathy: At this earliest stage there may be small areas of balloon-like swelling in the retina’s tiny blood vessels. Blood vessels become weak and may leak tiny amounts of blood and fluid into the retina This does not affect sight, but an optometrist will be able to identify the leaks as small dots on the back of the eye.
- Pre-proliferative retinopathy is when blood flow to the retina starts to be restricted.
- Maculopathy occurs when the macula area is damaged.
- Proliferative retinopathy is when the damaged retinal blood vessels start to produce growth factor chemicals. This causes new blood vessels to grow out of the existing, damaged vessels in the hope that they will begin to provide much needed nutrients and oxygen to the retina. The new vessels are extremely delicate and prone to bleeding. Proliferative retinopathy is highly likely to cause obscured vision.
Read more about this condition in our ‘Stages, Prevention and Treatment of Diabetic Retinopathy’ article.
A cataract occurs when the crystalline lens becomes cloudy. The lens is located directly behind the iris, and allows the eye to focus the image that is then projected onto the retina.
Cataracts are not specific to diabetes, but the condition is more likely to occur at an earlier age in people with diabetes. Studies have shown that people with diabetes have a 60% increased risk of developing cataracts.
Cataracts are generally treated with eye surgery. The existing lens is removed and replaced with an artificial intraocular lens. The surgery is considered to be low-risk, and over 90% of cataracts operations have proven to be effective at restoring working vision.
Glaucoma is commonly associated with sufferers of diabetes. One rare form, neovascular glaucoma, has been proven to have a direct link with the condition. Scientists are divided on whether the more common open-angle glaucoma actually has a direct link with diabetes.
Towards the end stages of diabetic retinopathy, the retina is deprived of oxygen and nutrients. This triggers the release of a chemical which stimulates the growth of new vessels within the eye, in an attempt to provide the eye’s structures with nutrients.
These new vessels are weak and prone to damage. They grow into the trabecular meshwork, which drains the fluid at the front of the eye. This increases pressure inside the eyes, damaging the optic nerve and negatively impacting vision.
Glaucoma can be treated through a number of different methods. Eye drops, surgery or laser eye treatment are all common solutions. However, early diagnosis is of the utmost importance, as existing damage cannot be reversed.