A study published in this month's issue of the Journal of Cataract and
Refractive Surgery suggests that rigid contact lens users should stop using
contacts and switch to glasses 3 to 6 weeks before having pre-LASIK
examinations, rather than the traditional 3 weeks.
The study found that only 56 percent of eyes (31 of 55) achieved a stable
refraction after 3 weeks, but 78 percent were stable after 6 weeks, said study
author Patricia Tsai, MD, currently a fellow at the Massachusetts Eye and Ear
Infirmary in Boston. The study was performed at the University of California San
Francisco School of Medicine's Department of Ophthalmology.
Rigid contact lenses can cause a warping of the cornea, the clear outer part
of the eye that is operated upon during LASIK, the popular laser-based vision
correction procedure. That warping can result in improper calculations for laser
treatments. The problem is routinely managed by having patients stop using their
rigid contacts several weeks before evaluation to allow the cornea to return to
its natural shape. Once achieved, a stabile refraction (stable set of
measurements of the eye's optical power) can be obtained. A stable refraction is
needed to guide the laser used in LASIK to make the most accurate vision
correction, Tsai said.
Based on the study, Dr. Tsai recommends contact lens users call their
ophthalmologists well before scheduling a pre-LASIK eye examination to learn how
long they should discontinue contact lens use.
In the study, rigid gas-permeable (RGP) contact lens users were instructed to
discontinue wearing lenses 3 weeks before the initial examination. Patients were
examined at 3-week intervals until a stable refraction was achieved. Of 55 eyes
of 28 patients, 31 eyes achieved refractive stability by the second visit (early
group, 3 weeks after discontinuing contact lens use). But 24 eyes required more
than 2 visits, (late group, at least 6 weeks after discontinuance) to achieve
stability. No significant between-group differences were observed in age, or
gender of patients, or anatomical or optical characteristics of their eyes.
However, the study suggests that the number of years that a patient has been
wearing rigid contact lenses may influence the time it will take for a stable
refraction to be achieved. The study also noted that the corneal changes are
most pronounced with rigid gas- permeable contact lenses, although they can
occur with soft contact lenses as well.
The study is entitled "Predicting time to refractive stability after
discontinuation of rigid contact lens wear before refractive surgery."
While the percentage of RGP contact lens users is a relatively small
percentage of all contact lens users, the study's findings support an important
consideration in optimizing LASIK outcomes and enhancing patient satisfaction,
said Samuel Masket, MD, chairman of the Eye Surgery Education Council, the
public education arm of the American Society of Cataract and Refractive Surgery