Wavefront-guided LASIK re-treatments a success

February 15, 2005

New Orleans—Wavefront-guided LASIK re-treatments in post-LASIK eyes resent a good option for refractive correction, according to results of a small study in which nearly all eyes showed a reduction of pre-existing total aberrations and some reduction in higher-order aberration components.

New Orleans-Wavefront-guided LASIK re-treatments in post-LASIK eyes resent a good option for refractive correction, according to results of a small study in which nearly all eyes showed a reduction of pre-existing total aberrations and some reduction in higher-order aberration components.

Ronald R. Krueger, MD, medical director, department of refractive surgery, Cleveland Clinic Cole Eye Institute, described a small case series in which patients underwent wavefront-guided LASIK with the Alcon CustomCornea platform for the correction of residual myopia and astigmatism after standard LASIK.

Dr. Krueger treated 29 eyes in 26 patients; eyes included in the study were symptomatic, post-LASIK eyes, and those in which some level of visual complaint led to dissatisfaction after the initial procedure.

Speaking during a refractive surgery session at the American Academy of Ophthalmology annual meeting, Dr. Krueger also described a new way of classifying aberrations. He said absolute magnitude outcomes are considered to be either reduced or induced, and directional magnitude values (those with a plus or minus sign) are a success if less in magnitude of the same sign or less than half the magnitude of the opposite sign, induced if greater in the same sign, overcorrected if greater than half of the value of the opposite sign, and induced and overcorrected if the value is greater and the sign is opposite.

The patients included nine females and 17 males with an average age of 45 years. At 1 week after surgery, all 29 eyes were available for follow-up; at 3 months, 21 eyes were evaluated; and at 6 months, 10 eyes.

UCVA was 20/20 in 31%, 38%, and 60% of available eyes at 1 week, 3 months, and 6 months, respectively. BSCVA was 20/20 in 72%, 81%, and 90% at the respective time points.

Looking at the overall gain or loss in BSCVA, the vast majority of eyes either stayed unchanged or gained 1 or more lines at 3 and 6 months.

Dr. Krueger also provided the outcomes for aberrations.

"Looking at the total aberrations versus the higher-order aberrations at the various time points, we were able to achieve good success-90% to 100%-in reducing total aberrations and quite good success-anywhere from 60% to 70%-in reducing higher-order aberrations," he said.

He also reported that 100% of defocus was reduced, as was about 80% of astigmatism, measured by mm of error. About 54% of coma was reduced, and other terms were reduced by about 37%.

Using directional value magnitude to measure outcomes, Dr. Krueger noted a success rate of about 70% to 80% in correcting small wavefront refractive errors, either by reducing or not overcorrecting the magnitudes. Some overcorrection and induction of cylinder occurred in the re-treatment.

In individual terms with directional value, about 65% of coma values were reduced, which Dr. Krueger described as a notable and significant improvement. Trefoil values were reduced somewhat less, about 25% to 50%, depending on which type of trefoil was being measured.

Spherical aberration correction "Spherical aberration, which is usually a challenge to treat primarily and one of the main culprits in night vision problems postoperatively, had great success overall in this particular cohort," Dr. Krueger said. "There was only 12% induction and 88% reduction of spherical aberration when looking at absolute magnitudes."

Secondary astigmatism did not show a significant reduction, with a success rate of about 30% to 50%.

Dr. Krueger offered several pointers from his experience in performing LASIK re-treatments.