Do you mean:
1) I have glaucoma/cataracs/am visually impaired, then, yes, you need better vision than 20/200.
or
2) I need glasses because I am myopic/astigmatic/etc, then, you can still be a good radiologist since you can correct that.
Keep in mind that what makes a good radiologist is not just eyes, but actually knowing what you're looking at, so experience/studying/a well developed approach/an awareness of your own limitations and the technical limitations of the study are important, not just eyes.