Q: Is it possible to have one eyes quantity 0 ?
A: Yes, if you don't select any value for the specifications like Power, cylinder for one eye then only one eye specifications will be added in Cart.
Our extension checks whether the values are filled in specifications i.e. Power, Cylinder & etc. and then checks the quantity selected if no values are selected for the specifications then no qty field is checked, so one eye lens can also be added in cart.