Excimer laser produces positive results in hyperopia

Houston-Hyperopia treated with the wavefront-optimized Allegretto Wave excimer laser (WaveLight) achieved good long-term stability, even in patients with 4 to 6 D of hyperopia. The wavefront-optimized platform also achieved excellent outcomes for hyperopia up to 6 D with 5 D of cylinder, reported Charles R. Moore, MD.

"The literature on hyperopic LASIK varies considerably in the conclusions on hyperopic stability," said Dr. Moore, medical director, International EyeCare Laser Center, Houston. "Good long-term stability has been reported in some platforms and very poor long-term stability has been reported in many.

"Comparisons also vary among older laser systems, smaller optical zones, and treatment ranges," he said. "There are few reports in the literature in which the follow-up is longer than 1 year."

"This approach is on the right track with that conclusion," Dr. Moore said.

A 5-year study conducted by John Marshall, MD, and colleagues used the Summit Apex Plus laser to treat 47 patients with 7 D of hyperopia and found significant regression; they concluded that hyperopia exceeding 3 to 4 D should not be treated with the Summit laser.

The same investigators then conducted a study with a 7.5-year follow-up with the same laser and determined that PRK was a better treatment option for hyperopia, plus it produced fewer side effects, according to Dr. Moore.

Another 5-year study used the Technolas laser (Bausch & Lomb) to treat 125 eyes with up to 6.5 D of hyperopia. Results showed substantial regression associated with higher degrees of hyperopia and drier eyes, he said.

Dr. Moore reported that a study of PRK and LASEK performed with the Nidek 5000 laser to treat 216 eyes showed better refractive stability with LASEK than with PRK, but no reason was given for that finding.

Achieving stability

In the Allegretto Wave study, a total of 290 eyes with hyperopia or hyperopic astigmatism were treated with the Allegretto Wave excimer laser as reported in the FDA clinical trial for pre-market approval (PMA). The study was conducted at 10 sites in the United States. The last treatment was performed on Dec. 11, 2002, resulting in a greater than 3-year follow-up for all eyes. The spherical equivalent in this group of patients ranged up to 6.6 D.

"The initial PMA study showed stability was reached at the 3-month examination, with a 0.12-D change and a 0.01-D change thereafter," Dr. Moore reported.

The investigators then re-examined the patients and assigned them to groups based on the degree of correction they received: 0 to 2 D, 2 to 4 D, and 4 to 6 D. All patients had been treated with a 6.5-mm optical zone with adjustable blend out to 9 mm, he explained.

"The predictability was good with 73% of spherocylinders corrected within 0.5 D of emmetropia, and 91% of spherocylinders were corrected within 1 D of emmetropia; 90.2% of all patients were within 1 D of emmetropia," he stated. "These results were very good for hyperopia."

Dr. Moore and colleagues have only been able to re-examine 107 patients. Some were lost to follow-up due to Hurricane Katrina and others were reluctant to return. The mean follow-up is 3.7 years.

"Most of the long-term patients (60%) are in the 0-to 2-D hyperopic range, 28% are in the 2-to 4-D range, and 12% are in the 4-to 6-D range," Dr. Moore said. "We were unable to correct vision in some of the younger patients with latent hyperopia for complete cycloplegic refraction, and we treated all manifest refractions in this cohort with no surgeon nomogram adjustment."

The refractive changes correlated best with the keratometric changes in the patients with 4 to 6 D of hyperopia, which implied subtle true regression, but less than 0.5 D. The refractive differences correlated best with the untreated latent hyperopia in the lowest hyperopic group, he continued.