It seem to be getting hard In California since the Santa Monica incident where a number of people were killed by a older driver out of control.
If you do not pass the vision test : Va can be 20/20 in one eye but less than 20/40 in the other eye, they ask you to see an eye doctor and an extensive form needs to be filled out. If one question is not answered, or anything crossed or whited out, a new form must be completed.
Dr. O.
forgot to add vertical field should be no less than 80 degrees, but again this may vary a bit.
State requirements do vary state by state. For most the general standard is you can get an unrestricted license if your best eye is 20/40 or better. Your visual field should be 120degrees or better. You can get a restricted license if your visual acuity is worse than 20/40 but no worse than 20/70 and visual field is 120 degrees or better. Some states the horizontal binocular visual field limit is 110 degrees. Also, some states let you drive w/ biOptic lenses.
It's probably best to check w/ your DMV.
I think that most states require 20/40 vision in one eye. But it differs state by state. For example, Florida's requirement is less stringent.