Diabetes can be a devastating disease! In the case of the eye, diabetes creates four distinct problems, either alone or in combination.
First, in an effort to dilute or concentrate blood glucose, an out of control diabetic sustains fluid shifts. Some of the fluid can get into the lens of the eye and create a cataract by causing bubbles to form in the lens. The bubbles scatter light and result in vision impairment.
Second, the cell that acts like the "Maytag Repairman" for the blood vessels is dysfunctional in diabetes. So blood vessel walls don't get the maintenance they need. Leaks can develop, and much like a leaky hose, a lot of leaks result in little or no flow, and the retina loses its blood supply. The body will attempt to rebuild the blood supply but it often does so in a disorganized way, resulting in blood vessel development in areas where they are not desirable. And these vessels leak even worse than the ones they replaced. Laser treatment can often reverse this but only to a degree. Diabetes control is necessary to keep the repair further damage from occurring and to assure the repair is effective.
Third, high blood sugar causes red blood cells to become sticky. The cells clump, forming "rouleaux", which can be large enough to clog small capillaries. This often leads to diabetic optic neuropathy or damage to the optic nerve (the cable that carries all the information the eye collects to the brain). Unfortunately, this cannot be repaired.
Lastly, when the retinal tissue becomes sick enough, it begins to swell. When this swelling occurs in the central vision area of the retina, vision can be distorted. This condition is called Cystoid Macular Edema. The same anti-VEGF medications used to treat macular degeneration can be used in this case, and often good outcomes can result.
A test performed by your family doctor, the Hemoglobin A1C, is very useful to detect trends in diabetes. We try to work with your family doctor so that we see and can follow the A1C results as this will often give us a head's up about your diabetic ocular disease!