Diabetes can have a devastating effect on vision if it is allowed to progress unchecked.  There is emerging new information about the best ways to manage the condition.  Clinical studies have shown that the proper control of blood sugar levels as well as blood pressure and cholesterol can delay or even stop the progression of diabetic retinopathy. 

Hemaglobin A 1c (HbA1c) is the correct way to assess the level of blood glucose.  The test measures the average level of glucose to which the blood cell has been exposed over its life so you are getting a summary of the blood sugar, not a momentary view as you would get with a single blood sugar measurement.  Patients with type 2 diabetes should have a HgbA1c of 6% to 7% (normal levels are 4% to 5.9% in healthy people).  In addition, blood pressure should be maintained below 130/80.

Studies have demonstrated that very small differences in the management of the disease can have a profound effect on the vascular complications of diabetes.  One study (Diabetes Control and Complications Trial) showed that in a group of young diabetes managed in the usual way with glucose measurements and insulin injections twice a day versus a group having measurements three times a day with accompanying insulin, there was a five times greater risk of worsening of the diabetic retinopathy.

People with diabetes should have an ophthalmic exam once a year.  If they develop mild to moderate retinopathy the exam should done every six months and every two to four months if the vision has been effected by macular edema or prolifertive retinopathy.  While the exam should include measurement of the vision, it is not always an effective way to determine the condition of the retina.  This is because there are many factors which effect the vision other than the diabetes.  If there are any signs of progression a fluorescein angiogram should be obtained.  This is a photographic assessment of the retinal blood vessels.

There are numerous trials under way to identify the best means of treating diabetic retinopathy but the gold standard at this time is panretinal laser photocoagulation (PRP).  This technique creates numerous small laser burns in the retina and has been shown to slow or stop the progression of the disease; it will not undo prior damage.  This technique has been around for forty years, the only change has been the light energy delivery system.  In my training at Medical College of Virginia, some of the pioneering work was being done.  In the early years, the light energy was collected from a huge airport searchlight and narrowed down to a fine beam that would pass through a pupil and into the eye.  Now an Argon laser is the size of a desktop computer.

Studies have shown that only 7% of diabetics reach optimum control of HbA1c, blood pressure and cholesterol and so there is a good chance that an effected patient will worsen over time.  It is therefore important that diabetics seek out quality eye exams on a regular basis.