Allegretto laser works well for both hyperopia and myopia correction, says FDA trial data

THE Allegretto (WaveLight) laser provides excellent clinical outcomes for the treatment of both hyperopia and myopia, according to the latest clinical data presented from two FDA trials at the annual ASCRS Symposium on Cataract, IOL and Refractive Surgery.

Refractive surgery with the Allegretto resulted in 20/20 vision or better in 87% of myopia patients and 66% of hyperopia patients at six months. In both trials, patients also experienced a mean decrease in problems with postoperative glare, measured by a subjective questionnaire taken both preoperatively and postoperatively.

"This is remarkable. It’s unheard of in the annals of refractive surgery," said investigator William Bond MD, who reported the results of the hyperopia trial.

Dr Bond reported six-month data on 269 eyes in the Allegretto FDA trial for hyperopia. Patients had up to 6.5 D of hyperopia and up to 4.0 D of astigmatism. Some 89% of patients had 4.0 D of hyperopia or less.

Almost 72% of eyes were within 0.5 D of target spherical equivalent (SE) at six months. While UCVA was 20/20 in two-thirds of the eyes at six months, almost 30% achieved 20/16 and more than 95% were at 20/40.

"These are very good results, especially considering that we had some high hyperopes. With these eyes you can definitely get into some pathology," Dr Bond said.

In terms of best-corrected postoperative vision, only 1.5% of eyes lost two or more lines. More than 40% actually gained one or more lines. This large gain in best-corrected vision is very unusual in hyperopia, he commented.

Dr Bond noted that the hyperopia trial results with the Allegretto laser compare favourably with the six-month FDA trial results seen with the Alcon LadarVision and the Visx S2/S3. For example, at six months, UCVA was 20/20 or better in 66% of eyes in the Allegretto trial, compared to 43% with LadarVision. At three months, the only time period for which data was available, UCVA was 20/20 in 46% of eyes in the Visx trial.

William Bond

He reported that the Allegretto was comparable to the other systems, and even superior in most outcome categories. However, results on the Allegretto were not significantly different than other lasers in terms of postoperative UCVA of 20/40 or better, SE within 0.5 D of target, or loss of two or more lines of visual acuity.

Karl Stonecipher MD reported one year results from the FDA Allegretto myopia study of 901 eyes treated for up to -12 D of myopia and 6.0 D of astigmatism. The one-year results available for 90% or 813 eyes showed that 85% of eyes were within 0.5 D of sphero-equivalence at one year. More than half of the eyes (56%) achieved uncorrected visual acuity of 20/16, while 99% were at 20/40 or better at three months.

He noted that even high myopes did well in the long term. Some 80% of eyes with more than 7.0 D of myopia were within 0.5 D of the target range, compared to 86% of eyes with less than 7.0 D of myopia. Some 80% of those with more than -7.0 D of myopia also achieved UCVA of 20/20 or better, while 89% of those with less than -7.0 D attained the same results.

The Allegretto also showed good outcomes in terms of BSCVA. The loss of two or more lines of BSCVA was 0.6% - was well within the FDA target of less than 5%. Moreover, more than 58% of eyes gained one or more lines.

"This outcome is a result we’re very excited about. Patients feel very comfortable with this laser. This is why we feel many ophthalmologists are going to be driving a German laser pretty soon," Dr Stonecipher said.

He commented that the Allegretto laser had produced superior six-month results in FDA studies when compared to trials of four other lasers - the Alcon LadarVision, the Visx S2/S3, the LaserSight and the Nidek machine.

While almost 90% of eyes had UCVA of 20/20 or better after LASIK with the Allegretto, only 40% to 55% of the other lasers achieved the same results. While 87% of eyes on the Allegretto came within 0.5 D of target refraction at six months, only 65% to 78% of the other lasers did so.

The researchers also administered questionnaires to patients asking how much glare they experienced from bright lights such as headlights and streetlights, before and after LASIK. Mean scores on the test improved significantly after LASIK with a p value of 0.001.
Increased glare was more likely to occur with higher myopic corrections and residual refractive error. It was not correlated with mesopic pupil size, Dr Stonecipher emphasised. He related this finding to the large effective optical zone provided by the Allegretto laser, which extends to the full diameter of the labelled treatment with blends occurring in the periphery.

In the Allegretto hyperopia trial, patients also experienced a mean improvement in glare from bright lights after LASIK. The eyes with the most preoperative glare were the ones most likely to improve after surgery. Patients reporting lower scores after LASIK were more likely to have larger pupils. However, large pupils alone did not predict worsened scores, Dr Bond said.
When the researchers asked patients about the quality of their vision just during night driving, there was no association between pupil size and glare experienced after surgery, Dr Bond added.
"The results of the trial are very striking, and are likely due to the use of the prolate software in Allegretto.

The Allegretto features a 0.95 mm flying spot with a Gaussian beam profile and an active tracker with a response time of less than 6.0m/s. The tracker does not require dilation of the eyes.
"Because the laser is quicker, you get better results. The eyes have less time to dry out. One of the bigger challenges in refractive surgery is the need for re-operations. With the Allegretto we have a re-operation rate of 3% and that’s without individual nomogram adjustments. That’s unheard of in LASIK," said researcher Guy Kezirian MD, FACS, whose company organised both FDA studies.

The WaveLight Allegretto treats LASIK patients with an adjusted treatment profile (both prolate and aspheric) built into the ablation algorithm, which compensates for the spherical aberration which exists in an average healthy eye. The correction aims for a prolate cornea with an aspheric factor of -0.46 to compensate for and correct for induced spherical aberration in LASIK.

The Allegretto also reduces spherical aberration by increasing the optical zone size and correcting peripheral ablation by reducing laser energy in the periphery. It’s more effective with myopia than hyperopia in producing a true optical zone of 6.5mm and reducing spherical aberration, Dr Bond explained.

"The Allegretto research was very well conducted. It’s a small flying spot with an excellent eye tracker - the most advanced type of laser. However, the LadarVision is also a small flying spot laser with an excellent eye tracker," surgeon Brian Boxer Wachler MD added.

William Bond MD
Pekin Memorial Hospital, Illinois, US
Email: bondeye@bondeye.com

Guy Kezirian MD
SurgiVision Consultants Inc, Arizona, US
Email: Guy1000@SurgiVisionConsultants.com

Karl Stonecipher MD
South Eastern Laser and Refractive Centre, North Carolina, US
Email: stonenc@aol.com

Top