Undercorrection occurs when an eye remains somewhat
nearsighted after refractive surgery. It is seldom
considered a serious complication. Distance vision is better (if not perfect),
and near vision is still good. Undercorrection is much more common in people
with severe nearsightedness than in people who had nearsightedness of less than
Slight undercorrection may be considered an advantage. A little mild
nearsightedness will delay the onset of
presbyopia. And it may offset the effect of
progressive farsightedness (hyperopia). Also, the amount of undercorrection may
decrease after several years because of a phenomenon called the hyperopic
shift. Hyperopic shift is the gradual increase in farsightedness that may occur
for some years after radial keratotomy (RK) surgery.
Undercorrection may be successfully corrected with a repeat surgery.
But repeat operations tend to be less effective and less predictable than the