Can you use preservative free sterile water vials to clean eyes after PRK eye surgery?

Yes, you can use sterile water to clean the eyes, but this would not be the best choice. The best is use something that is more similar to tears, which as you know contain salt. The ideal solution would be sterile saline solution, not sterile water.

Preservative free vials are the recommended post-surgical drops. These should not replace any medicated drops that your surgeon may have you taking.  To avoid dilution of your medicated drops, do not take these immediately before or after use of your medicated drops.