Ortho-K, or OK lens, is a non-surgical vision correction method that reshapes the cornea using specially designed rigid gas permeable lenses worn overnight, allowing for clear vision during the day. It is FDA-approved, suitable for all ages, and has advantages such as being reversible, cost-effective compared to surgery, and beneficial for those with dry eyes or allergies. The treatment process involves an initial eye exam, fitting of trial lenses, and follow-up visits to ensure optimal fitting and eye health.