As for my opinion, overweight has no business with the eyesight, especially in a direct way. The indirect affect of weight and vision maybe the following reason, firstly, because of the overweight, you lack of exercises such as table tennis, badminton, football, golf etc. These sports will enhance the blood circulation volume and metabolism around the eyes to relief the eyestrain. Secondly, you know overweight people always like rich food with sweet; the sugar will decrease the absorb of nutrients of vitamin B which the eyes need. In order to get enough nutrients of the eyes, you must take care of nutrient balance with Calcium, protein taking, avoid food preference and control the sweet food quantity. These nutrient elements will protect your eyes and less sweet food will help the vitamin B1 remain.
I quite understand your concern. And it is true that being overweight could increase the risk of getting eye problems, because some eye problems could be resulted from high BP, high Cholesterol level, diabetes, etc. So, what I means is that you should be aware of those health threats and you should try to protect your health. It would be wise for you to lose weight before it is too late. Just pay attention to your exercises and diet.
Yes, overweight can cause some problems of eyesight. It is really possible. When you have the overweight, you may find that your body health will be affected too. Your eyes will be affected indirectly. When there is something wrong with your liver or other parts, you could find that your eyes will have the corresponding action. Thus, you'd better control your weight.