Although diabetes is a serious cause of eye disease, less than 5% of patients with diabetes suffer from severe visual loss due to their diabetes. Diabetic retinopathy is found in 77.3% of those with type-1 diabetes, and 25.1% of those with type-2 diabetes.
After 15 years of type-1 diabetes, 98% will have some form of diabetic eye disease. In type-2 diabetes, this applies to 78%.
In diabetes, hyperglycaemia (high blood glucose levels) causes increased retinal inflammation, such that the small blood vessels of the retina (back of the eye) become dilated and leak tissue fluid into the back of the eye. New blood vessels start to grow which ordinarily should not be there. Blood vessels may become blocked with tiny blood clots, disrupting the retinal blood supply.
Increased oxidative stress (the metabolic processes that produce oxygen) results in larger numbers of dangerous molecules called reactive oxygen species (ROS) in the retina. These can also damage DNA.
Advanced glycation end products (AEGs) – large molecules formed from fat, sugar and protein becoming stuck together found in the bloodstream – further exacerbate local inflammation, causing damage to the extracellular matrix (connective tissue).
Eventually, fibrosis (scar tissue) is formed in the eye increasing the risk of serious complications such as retinal detachment.
Symptoms include:
Other risk factors for diabetic eye disease are:
When the pupils are dilated and the retina is examined, the typical findings are –
Diabetic eye disease may be classed as mild, moderate or severe. It is also either proliferative or non-proliferative. In advanced disease, there may be macular oedema (swelling).
Diabetic eye disease increases the risk of cataracts and glaucoma.
In type-1 diabetes, diabetic eye screening is recommended 5 years after diagnosis, and once a year after this, for life. In type-2 diabetes patients should be screened at diagnosis and once a year after this, for life.
During pregnancy, women with type-1 and type-2 diabetes should have an eye examination within 3 months of becoming pregnant, probably again during the pregnancy, and for follow-up after giving birth. If women have gestational diabetes (diabetes that develops in pregnancy) they don’t normally need an eye examination as diabetes disappears when the pregnancy has ended.
Early diagnosis, proper treatment and follow-up are mandatory. If diabetes is not well controlled, this is likely to worsen the prognosis of diabetic eye disease. Optimal management of diabetes is crucial to preserve good eyesight. It’s vital to try and obtain an HbA1C level (a marker of how much glucose is stuck to your haemoglobin) of less than 7%.
Eye specialists state that diabetic eye disease takes 5 to 15 years to develop. In those with type-2 diabetes, their diabetes may have gone undetected for a long time before it was diagnosed, and therefore the patient should have an eye check at the time the diagnosis of diabetes is made. However, type-1 diabetes is diagnosed soon after a sudden onset, and so the patient can wait 5 years before needing to have an eye check.
Diabetic patients need to understand that working hard to get the best blood glucose control will reap benefits for their eyes and their vision in the long term.
https://www.ncbi.nlm.nih.gov/books/NBK560805/
This piece was written and provided by Dr Deborah Lee, Dr Fox Online Pharmacy.
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