How does diabetes affect your eyes?
Diabetes is a disease when the blood glucose (blood sugar) is too high. When a person is diabetic, the body does not produce enough insulin or is unable to use insulin as well as it should. Insulin is a hormone made in the pancreas which helps the body use glucose for energy. In the absence of sufficient insulin, excess blood sugar remains in the bloodstream. Over time, this excess blood sugar can travel to the eyes, kidneys, nerves and heart causing serious health problems.
In this article, we will focus on how diabetes affects the eyes.
High blood sugar can damage the blood vessels on the retina and lenses in the eyes resulting in diabetic eye diseases, which cause vision problems and even blindness in severe cases. These diabetic eye diseases include diabetic retinopathy, diabetic macular edema and cataract.
Diabetic retinopathy occurs when tiny blood vessels on the retina (nerve layer) are damaged. There are 2 main types of diabetic retinopathy:
Non-proliferative retinopathy is the early stage of diabetic retinopathy where there is usually no visible symptoms. However, there is a weakening of the capillary walls causing the formation of microaneurysms (tiny red dots scattered in the retina) and haemorrhage on the retina.
Proliferative retinopathy is the more advanced stage of diabetic retinopathy as more blood vessels become blocked. Blood vessels in the retina then begin to leak into the vitreous (gel-like fluid that fills the eye) causing blurring and patchy vision. Macular edema (swell) can also occur when fluid builds up in the macula (part of the retina at the back of the eye) due to leaky blood vessels. This can cause blurry and wavy vision as the macula allows us to see fine details and colours.
Cataract is a condition where the eye’s naturally clear lens becomes cloudy or opaque. Light is unable to pass through the lens resulting in blurry and cloudy vision. Cataracts can develop as we age but people with diabetes are more likely to develop it at an earlier age. The eye’s natural lens gets its nutrition from the aqueous humour, which provides oxygen and glucose. With increased glucose level in the aqueous humour, the enzyme in the lens will convert glucose to sorbitol, which changes the lens’ shape and clarity resulting in cataract formation.
How should we manage diabetes to lower the risk of having diabetic eye disease? Firstly, maintain a healthy lifestyle by eating well and exercising regularly. Secondly, keep an eye on blood sugar levels with the haemoglobin A1C (HbA1C) testing. HbA1C shows the average blood sugar level over the past 2 to 3 months – you want to keep the level to 7.0 or lesser. Having a level higher than 7.0 increases the risk of having health issues related to diabetes. Knowing your blood sugar level also allows you to work with your doctors to manage and treat diabetes. Lastly, going for yearly or regular eye examinations can detect or rule out diabetic eye diseases. Early detection also allows timely treatment to prevent any vision loss. Through an eye examination, the eye doctor can sometimes be the first to detect any undiagnosed medical conditions.