DIABETES CARE

DIABETIC EYE DISEASES
Ophthalmologist Dr Shanel Sharma explains why it’s vital to be vigilant if you have diabetes and why the eye is vulnerable to damage from the complications of diabetes.

Diabetes is the most common cause of blindness for people between 20 and 65 and diabetic eye diseases can affect anyone with diabetes whether type 1 or type 2. Chronically high blood glucose levels over time damage blood vessels throughout the body. Our small blood vessels are the most vulnerable and are affected first. These include the small blood vessels supplying our eyes, kidneys and our peripheral limbs (toes). People with chronically elevated blood glucose levels have substantially more, and more severe, retinopathy than those with lower blood glucose levels.

What happens in the eye is that the blood vessels become damaged and develop micro-aneurysms, start to bleed causing haemorrhages and stop carrying blood, resulting in retinal ischaemia. Ischaemic retina causes the release of a protein (VEGF – vascular endothelial growth factor), resulting in the development of sick and abnormal blood vessels, which can bleed or cause tractional retinal detachment and loss of vision. The other major way people lose sight is from diabetic macular oedema, from leaking of blood product into the macular. The macular is the part of the eye that allows one to read, look at people’s faces, or do any fine detailed work.

As there is usually a 10–15-year delay in chronically high BGLs and appearance of diabetic eye diseases, it is important to control BGLs well from the start. Although the damage to the eye is irreversible, early detection and treatment can reduce the risk of blindness by up to approximately 95%.

If you are diagnosed with diabetic retinopathy, don’t despair. Good blood glucose control can reduce its progression. People with diabetes who follow healthy eating principles can reduce their HbA1c levels by 1 to 2 percentage points. On a low GI diet, they can reduce can HbA1c levels by another 0.5 percentage points. While this may not sound significant, a decrease of just 1 percentage point in HbA1c levels will decrease the common complications of diabetes by 19% to 43%. Talk to your doctor or diabetes educator.

Reducing blood pressure helps too. The UK Prospective Diabetes Study showed a reduction of 10mmHg systolic and 5mmHg diastolic reduces the rate of retinopathy by 30%.

As diabetic eye diseases most commonly have no symptoms, it is essential to ensure that you are being screened regularly by your GP, optometrist or your ophthalmologist. Symptoms that are associated with diabetic eye diseases can include intermittent blurred vision, difficulty with focusing, loss of contrast, double vision or distortion to your vision. Additionally, diabetes is an independent risk factor for developing other eye diseases such as cataracts and glaucoma.

Protecting your eyesight is one of the most important things you can do to ensure quality and enjoyment of life.

Read more:

• Preventing Diabetic Retinopathy Progression 
• Diabetic Retinopathy and Systemic Factors 
• Blood pressure control for diabetic retinopathy 
• Risks of progression of retinopathy and vision loss related to tight blood pressure control in type 2 diabetes mellitus (UK Prospective Diabetes Study) 
• Dietary hyperglycemia, glycemic index and metabolic retinal diseases