Which statement is untrue?

• A. The Rx, if filled properly will always provide 20/20 vision
• B. The Rx should provide the intended correction when properly implemented
• C. An improperly filled Rx can cause eye strain
• D. Properly prepared glasses should be comfortable to wear

Answer: (A)

The important idea is that a prescription provides the necessary optical power to correct refractive error, but final vision is not guaranteed to be 20/20 for every person. Even when a prescription is filled correctly—lenses ground to the right powers, properly mounted, and aligned with the pupil—the actual visual acuity depends on multiple factors outside the Rx itself, such as the eye’s health, how well someone adapts to the lenses, and whether there are other optical or neural influences. So saying the glasses will always give 20/20 vision if the Rx is filled properly is not true. The other statements capture realities of proper practice: a correctly implemented prescription aims to provide the intended correction, an improperly filled Rx can cause eye strain, and well-made, properly fitted glasses should be comfortable to wear.