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New algorithm for MEL 80 excimer laser can preserve corneal tissue
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PARIS — A new customized ablation program for the MEL 80 excimer laser can remove less corneal tissue in some patients than the conventional software while providing comparable visual results, according to a surgeon speaking here.
Frank Goes, MD, presented the results of a study comparing the efficacy of the new Aberration Smart Ablation (ASA) Profile from Carl Zeiss Meditec at a company-sponsored symposium held during the European Society of Cataract and Refractive Surgeons meeting.
The study included 62 eyes of 31 patients with myopia ranging from –1 D to –8.25 D, with or without astigmatism. One eye of each patient was randomly selected to undergo LASIK using the ASA software. The fellow eye of each patient was treated using the standard algorithm.
Because the ASA software removes less tissue, differences in contrast sensitivity were expected, particularly in mesopic conditions, Dr. Goes said. However, no significant difference was found, he said.
Predictability of the treatments was also equal.
“Of course, when you look at the whole group, there were some differences, but the differences were not important,” he said.
Among a subgroup of patients treated for refractive errors from –3 D to –7 D, Dr. Goes said, eyes treated with the standard algorithm performed slightly better than eyes treated with the ASA. Also, more eyes in the higher ranges of the trial treated with the ASA had complaints of slight visual phenomena, such as glare and halos.
“But predictability was the same. And I would like to mention that not one of these patients has complaints or shows differences clinically between both eyes,” he said. “The key issue here is the ability to save tissue and save ablation depth.”
The ASA uses a significantly more shallow ablation depth than the standard algorithm, Dr. Goes said. For instance, in a patient treated for –1.5 D to –2 D using a typical 7-mm treatment zone, a standard algorithm would produce an ablation depth of about 110 µm. In that same patient treated with the ASA algorithm, the ablation depth would be 67 µm, Dr. Goes said.
He said he believes this algorithm will be beneficial in patients needing re-treatments or patients with thin corneas.
Beginning with errors above –6 D, the new algorithm removes more tissue compared to the standard algorithm, he said.