Eye complications of diabetes (1)

By Dr Olubiyi Adesina
Consultant Diabetologist
e-mail: fbadesina@gmail.com

Dr. Howard Root in 1935 succinctly stated that ‘eye complications in diabetes are frequent, distressing and destined to become one of the challenging problems of the future’. We have arrived at that future. As more and more people with diabetes survive longer as a result of improvement in the treatment of diabetes, more of these individuals with diabetes will be seen with complications of diabetes related to the eyes, kidneys and the nerves.

In order to understand this discourse, the definitions of some terms are necessary. The first term is the retina. This is the light sensitive region at the back or the inner layer of the eye. It is the part of the eye in which the image of any object we see is formed. Damage to this portion of the eye, principally its blood supply is referred to in medical parlance as retinopathy. The vitreous is the portion of the eye between the lens, which is the dark circle through which light passes and the retina. The vitreous consists of a gel like substance. Vitreous haemorrhage is when there is bleeding into the vitreous. The macular on the other hand is an oval shaped region in the middle of the retina which is responsible for high resolution vision.

In Nigeria, apart from infective causes, diabetes is another major cause of severe loss of vision. Diabetic retinopathy sadly remains neither incurable nor preventable, though the risk for developing it can be greatly reduced by taking some steps that will be outlined in this treatise. It is imperative to quickly identify individuals with diabetes at risk of developing the eye complications of diabetes and taking appropriate steps to greatly limit this risk. It is known that if individuals with diabetes follow the recommended care, their vision can be preserved for a long time.

The three key eye conditions that lead to blindness in those with diabetes include vitreous haemorrhage, detachment of the retina due to traction on it, and swelling around the macular referred to as macular oedema.

Diabetic retinopathy is a complication seen in both Type 1 and Type 2 diabetes. Individuals with Type 1 diabetes have a high incidence of severe eye problem and are thus more likely to develop significant eye problems during their lifetime. It has been proven that he longer the duration of the diabetes, the greater the risk of the development of this retinopathy. It is known that after 20 years of diabetes, nearly all those with Type 1 diabetes and more than 60% of those with Type 2 diabetes will have some degree of retinopathy.

It is known that the two eye conditions with the most potential for causing loss of vision – diabetic retinopathy and macular oedema – do not cause any symptom until it is too late, hence the need to screen the eyes of individuals with diabetes as appropriate.

Other conditions that may precipitate the development of or worsen the progression of diabetic retinopathy include pregnancy, persistent poor blood sugar control, concomitant hypertension, kidney disease and cholesterol disorders. Those with these conditions thus require closer scrutiny.

Clinical research has shown that very good blood sugar control not only reduces the risk of onset of diabetic retinopathy by 76% but also retards progression of preexisting diabetic retinopathy by 63% and reduces the need for laser surgery.

The wise and proper thing that individuals with diabetes should thus do is to go for an annual comprehensive eye examination called a dilated fundoscopy with specialist eye doctors called Ophthalmologists. This test allows the back of the eye called the retina to be seen to detect whether it has been damaged by the diabetic state which would warrant aggressive treatment. Individuals with diabetes should also have the pressure in their eye balls measured to detect glaucoma which is a common cause of painless visual loss in people with diabetes.

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