(Farsighted-Longsighted) Correction Difficulty with
Lasik, Bladeless Lasik, PRK, etc.
When you hear about
those 20-Minute Miracles who have instant perfect vision after
refractive surgery, you are not hearing about people with
hyperopia (farsighted, longsighted), you are not hearing about high
hyperopes, and you absolutely are not hearing about high hyperopes with
Hyperopia is significantly
more difficult to predictably and reliably correct than
myopia (nearsighted, shortsighted) vision. Hyperopic correction
is significantly more likely to
and regress at a greater percentage than myopic correction. Hyperopia
with astigmatism is a most challenging refractive surgery correction.
Hyperopia correction of more than about 3.00
diopters with conventional or custom
LASEK is very difficult to correct successfully without inducing additional
problems or without experiencing rapid regression. Vision recovery from
hyperopia is often significantly longer than recovery from myopic correction.
As with nearly all
excimer laser based refractive surgery, hyperopic correction can
be performed with both conventional
in myopic correction are simple: A laser removes tissue in the center
of the cornea to make it flatter. That's about it. For a shift in refractive
power to reduce hyperopia, the center of the cornea needs to be steepened
with a "bulge" outward. Think of the old saying, "If you can't raise
the bridge, lower the water." Myopic correction raises the bridge. Hyperopic
correction lowers the water. As with lowering the water under a bridge,
steepening the cornea is difficult.
With excimer laser
assisted hyperopic correction such as Lasik, Bladeless Lasik, PRK, LASEK,
and Epi-Lasik, the cornea is reshaped by removing a ring of tissue around
the outer edge of the cornea. By leaving the center of the cornea thick
and thinning the outer ring, the cornea changes shape relative to the
original shape of the cornea to give the net effect of a bulge outward
in the center.
All techniques are
very difficult to perform well. The bulging may not be centered or spherical,
causing regular or irregular astigmatism. Knowing just how much energy
to apply and where, is an art as much as it is science. The cornea tends
to naturally regress
back toward its original shape. Lasik, Bladeless
Lasik, PRK, LASEK, and Epi-Lasik hyperopic correction also tend to regress,
but at a relatively slow rate and will usually stabilize long before
full regression back to preoperative levels.
For all its technical
foibles, hyperopic correction is often considered very successful by
the patient. The reason is that hyperopes really cannot see very well
at any distance. The greatest advantage of hyperopic correction is for
someone who is also
Before presbyopia, the natural lens can somewhat "focus around" the
hyperopia. When you are presbyopic, you get hit with the full effect
of the hyperopia. That is why presbyopic hyperopes are often the most
satisfied patient even if the surgery is a marginal success. Any amount
of improvement is significant in its ability to help presbyopic hyperopes
function day-to-day and is greatly appreciated.
Rather than attempting
hyperopic correction by reshaping the cornea, the lens-based techniques
RLE may be much more appropriate. These techniques also have limitations,
such as the inability to correct astigmatism, but should be considered
as an alternative to
Lasik, Bladeless Lasik,
PRK, LASEK, or Epi-Lasik.