LASEK may only play support on refractive stage

By Cheryl Guttman

PHILADELPHIA - Even its most ardent supporters appear to agree that LASEK is a procedure appropriately considered for a select patient subgroup, at least until the long-term data supporting its use becomes available.
Researchers debated the relative merits of LASEK at a special session of the annual ASCRS conference.

Dimitri T. Azar MD believes data from lengthening follow-up studies with LASEK is encouraging and continues to use the procedure at his practice, albeit for a small proportion of patients. He performed the first LASEK procedure in the US in November 1996.

Currently, Dr Azar considers LASEK an alternative only for low myopes who are either interested in photorefractive keratectomy (PRK) or are not good candidates for LASIK perhaps because of a thin or irregular cornea or a lifestyle or occupation that makes them susceptible to ocular trauma.

"Our practice of performing LASEK in a limited patient population does not reflect experience showing that the surgery might not be successful, but rather a philosophy that one must be careful choosing patients for a procedure that is not yet well established," he said.

Dr Azar said that while some LASEK opponents argue the procedure is only PRK with replacement of dead epithelial cells over the ablated surface, in vitro studies performed in his own laboratory confirm that the epithelial cells can survive and maintain good viability after exposure to 20% alcohol for up to 30 seconds.

He said that his experience shows LASEK is associated with less pain compared to PRK, though he is not convinced of its other purported advantages.
Jonathan B. Rubenstein MD also performs LASEK in a subgroup of patients seeking refractive surgery who are not eligible for LASIK.

While he said he too is withholding judgment on whether LASEK is truly any better than PRK, he shares the clinical impression that patients are more comfortable after LASEK and appear to experience faster visual recovery.
However, Dr Rubenstein voiced concerns that LASEK may prove to be no different than PRK in terms of postoperative haze.

Louis E. Probst MD reported that he does not perform LASEK at all. When patients are not eligible for LASIK, he considers PRK an alternative.
Dr Probst's reluctance to adopt LASEK reflects his view that it is not any less risky than LASIK, but rather just presents a different set of risks. His key concern relates to the potential for haze.

"In my view, LASEK is still surface ablation and thus has the risk of creating corneal haze. That is something I think we have to be realistic about when reviewing the potential pros and cons of LASEK.
"We need to hold off our conclusions about any safety advantages until we have more information and more follow-up evidence," he said.

LASIK is a safe procedure when compared to the possible complications of LASEK and Dr Probst's personal experience means he will retain the former as his method of choice.
"In my hands, microkeratome-related flap complications occur infrequently and when they develop, they are readily managed and usually end with a favourable result. In contrast, when haze occurs with a surface ablation procedure, it is not so easy to correct," he explained.

John Doane MD also emphasised that the relative risk of haze when performing LASEK rather than PRK is an issue which requires further study.
In theory, since both LASEK and PRK remove Bowman's layer to leave epithelium resting on raw stroma, both remain prone to haze development, he said.
Dr Doane pointed out that the best refractive surgery data produced to date has come from custom LASIK procedures performed in virgin eyes.

While PRK and LASEK may have a place in appropriately selected patients, he predicted LASIK will continue to be the predominant refractive surgery operation of the foreseeable future.
He observed that claims that the surface ablation procedures have the advantage of preserving corneal tissue might overstate the magnitude of that effect.

"There is a mild myth that PRK and LASEK preserve tissue. With those procedures, the ablation starts 60 microns from the surface, as opposed to 90 to 130 microns from the surface with LASIK.
"So, PRK and LASEK save some tissue but it is not in the 100 to 150 micron range that some suggest," Dr Doane said.

Both Dr Doane and Eric Donnenfeld MD noted that comparisons of safety between LASEK and PRK must take into account more contemporary experience with the latter procedure.
Dr Doane said that PRK has been the subject of some negative publicity, but more recent information indicates such poor perceptions of PRK may be unjustified.

Dr Donnenfeld agreed: "PRK is a good procedure and I am using it more and more in my practice. I don't think LASEK is any better than PRK. To me the PRK versus LASEK debate is a case of the emperor's new clothes. A lot of people are saying LASEK is better and their opinions put pressure on others to see advantages for LASEK, even though they are not really there."

LASEK enthusiasts note that the advent of wavefront technology could make LASEK the ablative procedure of choice.
However, the role of LASEK in wavefront-guided ablations also remains to be defined through clinical studies and, for now, remains a subject for debate.

"If we observe that the epithelium maintains its thickness after LASEK, then LASEK would be better than LASIK in avoiding the noise introduced by the additional 100 microns of stroma over the wavefront-guided treatment area," Dr Azar said.
Dr Doane added that an argument against use of LASIK is that higher order aberrations are introduced with the replacement of the flap and while they are seen in early follow-up, they may be meaningless clinically both in the short and long term.

"Furthermore, we might expect that PRK and LASEK are also associated with higher order aberrations early after treatment, and if wavefront and topographic treatments are worth their salt, any true, long-term, flap-induced higher order aberration changes should be predictable and treatable," he said.

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