Is it possible to get 20/20 vision again without surgery?

Possibly: If your eye is healthy and the only reason for vision less than 20/20 is what is known as "refractive error", then it may be correctable with eye glasses or contacts without surgery. But if you have a particular diagnosis, an ability to improve vision to 20/20 depends on the condition which you have.

Normal aging changes: It is also possible for a person's refractive error (glasses or contact prescription) to change over time, and sometimes spontaneously improve. People often drift less nearsighted in their late forties through mid-60's, and then often more nearsighted after that (due to early cataract). Patients are always amazed when i tell them that their glasses prescription has improved since their last exam.