A method for modifying focal length of lenses of a HMD in accordance with a user's eyeglass prescription data and without the user having access to the eyeglass prescription data is disclosed. The method includes receiving an identifier that uniquely represents the user viewing content on the HMD. The method also includes obtaining eyeglass prescription data corresponding to the unique identifier that includes data for correcting eye defects of the user. The data is then applied by modifying optical properties such as focal length of the lenses to provide corrected vision to the user while the user views content on the HMD without the user having to wear prescription eyeglasses or contact lenses.