Latest generation excimer laser safely corrects myopia and myopic astigmatism

Rapid ablation enables precise PRK and LASIK, surgeon says.

A new generation excimer laser safely corrects myopia and myopic astigmatism with few complications, a study showed.

The study focused on the WaveLight Allegretto Wave Eye-Q excimer laser system (WaveLight/Alcon) used to perform PRK and LASIK.

“These data are comparable or even better than those that supported FDA approval of this device in 2007,” Esmeralda Costa, MD, said. “The WaveLight Wave Eye-Q excimer laser system is effective and predictable in myopia and myopic astigmatism correction, leading to good visual and refractive outcomes. It’s fast, with less tissue ablation, and has a good safety profile.”

The WaveLight Allegretto Wave Eye-Q excimer laser operates at a pulse frequency of 400 Hz, which enables rapid ablation. The platform’s Custom-Q software corrects for the Q-value, enabling the preservation of corneal asphericity, Dr. Costa said.

Patients and preoperative values

The study included 241 eyes of 187 patients (123 women and 64 men) with a mean age of 34.3 years (range: 20 to 54 years). Of the 241 eyes, 219 underwent PRK and 22 had LASIK.

Primary outcome measures were preoperative and postoperative best corrected visual acuity, postoperative uncorrected visual acuity, residual refractive error, safety and complications. The minimum follow-up interval was 6 months, Dr. Costa said.

Among all patients, mean preoperative Snellen BCVA was 1.06 and mean spherical equivalent was –3.57 D, with 0 D to –8 D of sphere and 0 D to –4.50 D of cylinder.

Among PRK patients, mean preoperative BCVA was 1.07 and mean spherical equivalent was –3.31 D, with 0 D to –6.25 D of sphere and 0 D to –4.50 D of cylinder.

Patients in the LASIK group had a mean preoperative BCVA of 0.98 and mean spherical equivalent of –6.34 D, with –4.50 D to –8 D of sphere and 0 D to –2.50 D of cylinder.

Outcomes and conclusions

Both groups combined had a mean postoperative UCVA of 1.03. The improvement in mean UCVA yielded an efficacy index of 0.97. Results showed that 77.2% of eyes had final UCVA of 20/20 or better, and 95.4% of eyes had final UCVA of 20/25 or better.

Predictability data showed that 88% of eyes had a final spherical equivalent within 0.25 D, 98% of eyes had a final spherical equivalent within 0.50 D and all eyes had a final spherical equivalent within 1 D.

In the PRK group (219 eyes), 198 eyes had a final spherical equivalent within 0.25 D and 217 eyes had a final spherical equivalent within 0.50 D.

In the LASIK group (22 eyes), 14 eyes had a final spherical equivalent within 0.25 D and 19 eyes had a final spherical equivalent within 0.50 D.

BCVA improved by one Snellen line in 28 eyes (11.6%) and two lines in three eyes (1.2%). Data showed three cases of moderate haze in the PRK group, with one patient losing one line of BCVA. No patient lost more than two lines of BCVA, and no patients required re-treatment.

The laser’s software enables cyclotorsional pre-alignment, Dr. Costa said.

“We introduce the data on the machine,” she said. “We don’t do marks on the patients. The laser has a perfect centration method.”

Dr. Costa explained why she and colleagues prefer PRK over LASIK.

“We are coming back to the surface right now. There’s a general tendency toward that,” she said. “The second reason is because we are a university hospital, so we have lots of residents and all of them perform refractive surgery. PRK is safer than LASIK, of course.” – by Matt Hasson

• Esmeralda Costa, MD, can be reached at Department of Ophthalmology, Coimbra University Hospital, Praceta Mota Pinto 3000, Coimbra, Portugal; e-mail: esmeraldaguedes@gmail.com.