For
individuals over 40 who are considering refractive surgery to decrease dependence
on glasses and contact lenses, clear lens replacement (CLR) is an exciting option.
In essence, this procedure entails removing the natural lens of the eye and replacing
it with an intraocular lens (IOL) implant. The procedure is essentially the same
as a cataract operation with lens implant, however, in this case, the procedure
is completed prior to cataract development for the refractive advantage. With
the benefit of powerful ultrasonic instrumentation to measure the length of the
eye to within 100ths of a millimeter, and sophisticated IOL formulas, ophthalmologists
have become very accurate at determining the proper IOL power to decrease post-operative
dependence on eyewear.
CLR is a procedure that is more
invasive than LASIK, PRK, and Intacs, with consequent greater potential risks.
However, CLR may be an excellent alternative to these procedures for people already
wearing bifocals or for those who do not qualify for other refractive procedures
due to extremes of refractive error. Because CLR requires entering the eye to
place the lens implant, the patient has a small risk of infection inside the eye
(endophthalmitis) that is not present in the other, above mentioned, refractive
procedures (LASIK, PRK, and Intacs). Unlike these procedures, however, CLR avoids
any treatment of the cornea and instead changes the refractive power of the eye
in a potentially more natural position (i.e., natural lens of the eye). CLR, thus,
avoids any significant risk of reduction of contrast acuity. Because
CLR requires removal of the natural lens of the eye, the patient is subsequently
unable to focus at near (accommodate). This is why CLR is best suited for patients
over 40 who are already wearing bifocals. One potential solution to this problem
of accommodative loss is implantation of the Array multifocal IOL implant. This
implant allows focusing at both near and far, allowing most patients to read small
size print and drive a car without glasses, following implantation of the lens
in both eyes. A total of 41% of patients implanted with the Array multifocal lens
in both eyes reported that they never wore glasses post-operatively. The drawback
of this lens is that approximately 15% of patients have severe difficulty with
halos and 11% have severe difficulty with glare. Less than 1% of patients have
had such severe visual difficulties following implantation of the Array lens,
that they have requested removal of the lens. A second
alternative for patients who are considering CLR, but who do not embrace the notion
of wearing reading glasses following surgery, is monovision. With monovision,
the traditional monofocal IOL implant is inserted bilaterally, however, the patient's
dominant eye is corrected for distance and the non-dominant eye is corrected for
near. This choice is also an excellent one, but not necessarily an option that
would be tolerated by everyone. An excellent method to determine whether this
is a viable option is to correct the eyes in monovision fashion as a trial, prior
to consideration of surgery. Those patients that tolerate monovision with contact
lenses (or perhaps glasses), will likely tolerate and enjoy this visual solution
following surgery with lens implants.
Type
of the Refractive Surgery
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