Most people who have radial keratotomy (RK) surgery
gradually become more farsighted for at least 8 to 10 years after surgery. This
is called the hyperopic shift. It is not clear what causes
the shift. It's also not clear how long it may last or how bad it will get.
The effects depend on the person's age and whether
the person is nearsighted or farsighted after the surgery.
People who are still slightly nearsighted after
surgery (undercorrected) may find that their distance vision slowly improves as the hyperopic shift occurs.
People younger than
40 may not notice the shift. That's because their eyes
can adjust to the change.
People around age 40 may get
presbyopia sooner as a result of the hyperopic shift. They may need reading glasses.