Question: How might hyperglycemia affect a patient’s prescription?

Answer: With hyperglycemia, the lens accumulates sorbitol which in turn pulls water into the lens. This water makes the lens rounder, and causes the eye to become myopic (with images focussing in the vitreous in front of the retina).

It can take a while for this residual myopic affect to recede, so it’s a good idea to make sure that a diabetic’s glucose has been stable for a couple of weeks before prescribing glasses.