There are two ways that vision becomes blurry due to diabetes. The first way occurs around the time of diagnosis and is related to poorly controlled blood sugar. The second way that vision is decreased from diabetes is from diabetic retinopathy; the eye disease caused by diabetes. The actual eye disease usually develops years after the diagnosis of diabetes is made.
Usually, patients diagnosed with diabetes have elevated blood sugar due to insufficient supplies of insulin. Insulin, produced by the pancreas, is a hormone that takes sugar out of the bloodstream and allows it to be used as fuel for our cells.
Not enough insulin ... blood sugar levels skyrocket.
With large elevations of sugar, vision can be affected. The large amount of sugar can enter part of the eye, and eventually, the sugar permeates the natural lens of the eye.
The sugar, glucose, is altered slightly inside the lens to sorbitol, a derivative of the glucose. Both sugar and sorbitol attract water. As a result, the increased water content of the lens, changes the focusing power of the eye causing a change in the vision.
In other words, high sugar concentrations lead to increased water content of the eye. This changes the vision and also the strength of the glasses needed to see well.
There is usually a lag between sugar control and stable vision. The vision may stabilize after a few weeks of controlled sugar.
Once the blood glucose has become controlled with medication and has been stable for a few weeks, it is then time to visit the eye doctor.
The eye doctor, ophthalmologist or optometrist, should be checking you for glasses, and for the presence of diabetic retinopathy.
On occasion, patients come in to see me slightly agitated with their own eye doctor. They had just picked up their new glasses, but they don't seem to work! What's going on?
It's not the eye docs fault! At the time of the eye glass exam, the sugar may have been out of control, glasses prescribed, but the sugar levels changed by the time the glasses were made and picked up.
The undiagnosed diabetes caused a major change in the prescription!
Patients that have had diabetes need regular eye exams to prevent vision loss from diabetic retinopathy. While vision changes will still occur with large fluctuations in the sugar, the diabetic retinopathy becomes the biggest permanent threat to vision over time.
Randall V. Wong, M.D. is a retina specialist practicing in Fairfax, Virginia. He has established an authority site to promote health education about retinal diseases; diabetic retinopathy, macular degeneration and retinal detachments.