All adults with diabetes should get a dilated retina examination at diagnosis and then at least once a year. Non insulin dependent diabetes mellitus (NIDDM or type 2 diabetes) is by far the commonest form of the disease. Good blood sugar control is valuable, but does not mean that retina checks are not required, in fact about 1 in 5 people will have some signs of diabetic retinopathy at the time of diagnosis. There are estimated to be over 10 crore (100 million) people with diabetes in India and the number is rising fast.
Sight threatening diabetic retinopathy is exceedingly rare before puberty, so children with diabetes do not need a retina check till they are 12 years old, at which time they should start on annual retina examinations.
It is worth noting that at many eye examinations the retina is not checked in detail. As a general rule, for a diabetic retinopathy check you will have drops put in your eyes to dilate the pupils, be asked to wait for 15 minutes or more and then be examined, following this your vision will be blurred for a few hours (till the drops wear off). So if you have had an eye examination, but not had this done, then you have not had a diabetic retinopathy check. Another way of achieving the same thing is taking pictures of the retina, which is often possible without the need to put in dilating drops, but some patients will need dilating drops to get good quality pictures of the retina.
Just like a patient with high blood pressure will not be aware of this, as he or she feels well in themselves, and the condition is only picked up when the blood pressure is measured at a routine test, diabetic retinopathy can exist, even at a moderately advanced stage, where it is threatening the patients vision, but the patient does not notice any problems (has no symptoms). It is therefore essential to have a retina check at least once a year even if no visual problems are perceived for all people with diabetes over the age of 12.
Upto 50% of people with proliferative diabetic retinopathy will become legally blind within 5 years if they do not receive timely treatment and 98% of severe visual loss from the disease can be prevented if the disease is caught early, stressing the need for regular checks.
Diabetic retinopathy remains the leading cause of blindness in the working age population even in the developed world where healthcare systems are more advanced. However through years of national screening retina checks for all people with diabetes, the United Kingdom has succeeded in displacing diabetic retinopathy from the first place as a cause of blindness in the working age population. This proves that having regular retina checks is effective in reducing the chance of going blind in people with diabetes.
Timely treatment either with laser or injections of special drugs into the eye can improve vision or at least stop severe visual loss in most patients if the disease is detected early.