Laser platform leads to excellent results in LASIK for high myopia

Results are comparable to those of low to moderate myopia with previous-generation lasers.

Issue: June 2011

Alfredo Vega-Estrada

ISTANBUL — Performing LASIK with an excimer laser for photoablation and a femtosecond laser for flap creation is a safe, effective and predictable procedure in highly myopic eyes, according to a speaker here.

“The Amaris platform (Schwind) allows [us] to achieve excellent visual outcomes, with minimal induction of corneal aberrations. Results are comparable to those of low to moderate myopia with previous generation lasers,” Alfredo Vega-Estrada, MD, said at the winter meeting of the European Society of Cataract and Refractive Surgeons.

A retrospective, consecutive, noncomparative study evaluated the outcomes of primary LASIK in 51 eyes of 32 patients between the ages of 23 years and 61 years (mean: 36 years). All patients had myopia of more than 6 D, ranging from –6.75 D to –13 D. The operations were performed between March 2008 and January 2010, using the Amaris and the IntraLase (Abbott Medical Optics) laser.

“A significant reduction of mean spherical equivalent was obtained, from preoperative –8.66 D to –0.35 D, 6 months after surgery. Mean uncorrected distance visual acuity improved from finger [count] to 20/25. Almost 90% of the eyes were 20/40 or better. No eyes lost more than two lines of [best corrected visual acuity]. Ninety percent of the eyes remained the same or gained one or more lines,” Dr. Vega-Estrada said.

Predictability was high, with 90% of the eyes within 1 D of spherical equivalent.

Induced corneal aberrations were also evaluated, and although an increase in spherical aberration and coma was found, visual quality was not compromised.

“Spherical aberration and coma are known to be some of the most disabling aberrations because of the type of glare they induce. However, even in the eyes where the increase was statistically significant, we did not consider it clinically relevant, as it was within three standard deviations of the levels considered as physiological for the normal population,” Dr. Vega-Estrada said.

Study results

The results of this series of LASIK patients were compared with those published in the last decade. It was apparent that early-generation excimer lasers were inconsistent with predictability and efficacy, and the lasers have improved over the years as the technology advanced.

One of the most interesting studies, published in 2010 by Yuen and colleagues, evaluated the results of almost 40,000 eyes operated in a period of 10 years.

In 1998, less than 40% of the cases in the highly myopic group were within 0.5 D of spherical equivalent. Results improved steadily over 10 years, and by 2007 almost 65% of the cases were within 0.5 D.

“Today, thanks to the advanced technology of the new-generation lasers, and to the use of femtosecond laser for flap creation, we have almost 85% of cases within 0.5 D. The results in the high myopic group are now comparable to those of low to moderate myopia with the earlier-generation excimer lasers. Possibly, these outcomes will become even better in the future,” Dr. Vega-Estrada said.

As far as stability is concerned, long-term studies have shown that LASIK has stable results. In a Vissum Institute study published in 2008, a mean regression rate of 0.10 D of spherical equivalent per year was found between 3 months and 10 years after surgery.

“New laser technologies, advances in ablation profiles, the introduction of femtosecond laser for the creation of the flap and a better understanding of the risk for keratectasia have led refractive surgeons to move a step forward in the correction of high refractive errors. LASIK today is indeed a safe and effective option for high myopic patients,” Dr. Vega-Estrada said. – by Michela Cimberle

Alfredo Vega-Estrada, MD, can be reached at Vissum Institute, Avenida de Denia, s/n, 03016 Alicante, Spain; email: alfredovega@vissum.com.
Disclosure: Dr. Vega-Estrada has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.