Thank you for your answer. So my question refers to the adjustments, not to the "fixed" eyecharts. So, if someone e.g. has -2 prescription in the left eye (no astigmatism) and you want to find out, could one make a program that adjusts a picture on a screen say starting at showing a picture that someone with -1 would see properly, and gradually moving down (0.25 D increments) to -2 in such a way that the person would see it properly?
So the process is basically the opposite of the phoropter: in the phoropter, you change the lenses until someone can properly see a fixed eyechart; instead of changing lenses, would it be possible to adjust a picture on a computer screen in such a way that once the patient indicates that the picture is clear, you can read the correction? Thanks again