It sounds like you are worried about diabetic retinopathy in which case, unless you have diabetes, I think you may be a little too sensitive on the subject. How old are you? Your eye sight can and will change. As a general rule it will stabilize after reaching your early-mid twenties. It may still shift after this point, but usually no more than about a quarter diopter. Eventually you might start to get that old man I need reading glasses shift in your vision as you pass 40 (presbyopia for you technical types). These ages are just general rules of thumb, you may be different. If your optometrist says your eyes are healthy, I wouldn't worry. If you are at all concerned get yourself checked out ASAP as early detection has the best outcome. As long as your vision can be corrected to 20/20 you will have no problems getting a medical. For instance I have a correction of -4.5 (that’s the really really sh!tty line, above the E on the eye chart) and with glasses I can see 20-15 and with contacts I can read the 20-10 line. Just make sure you are correctable and have healthy eyes and I wouldn't worry.

On a side note, keep up the exercise and healthy eating habits. You will benefit greatly all over for this and it is much better (an easier) to stay in shape than regain shape, even though round is still a shape.