Hi and welcome
A lot of people recommend a mobile app called "carbs and cals", which allows you to visually measure serving size and as the name suggests carbs and calories.
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I do not personally use it but have seen it recommended by others on this forum.
As for your eyesight, it is quite common when reducing glucose levels rapidly for the eyesight to blur temporarily. The lens of the eye contains fluid, in which glucose is dissolved. As the concentration of glucose drops the refractive index of the fluid changes and the eye lens focuses light differently. As your sugar levels stabilize, your brain will compensate for the "new" eye lens characteristics and eye sight should return to normal.
Do you self test your glucose? What are your counts like. If you do not test, you should. Get yourself a monitor and some strips and test before and 2 hours after each meal until you know how your food choices affect you.
All the best.
Pavlos