Surgeons weigh surface ablation versus LASIK

May 1, 2008

LASIK and PRK are both safe and, over the long term, produce similar visual outcomes. A preference for one or the other can be based on both scientific evidence and personal opinions, and it is a complex decision that does not necessarily have a right or wrong answer. Physicians should fully inform patients of the pros and cons of both and respect the decision, suggested participants in a point-counterpoint debate.

Key Points

New Orleans-Many surgeons agree that the long-term outcomes of surface ablation and LASIK are similar, but the agreement ends there. In a point-counterpoint debate at the American Academy of Ophthalmology annual meeting, James H. Abrams, MD, who practices in Sacramento, CA, and Lee Shahinian Jr., MD, who practices in Mountain View, CA, took different stands on the safety and efficacy of surface versus lamellar procedures.

The question of whether surface ablation or LASIK is superior should be answerable through scientific study, but no clear winner has been declared despite the publication of numerous papers comparing the techniques, Dr. Abrams said. While a recent meta-analysis of papers comparing LASIK and PRK declared LASIK superior, it relied extensively on data from before the year 2000 and therefore did not reflect technological changes in the two procedures that could have influenced the results, he added.

"Traditionally these debates are battles of statistics without acknowledging the realties of how surgeons and patients actually arrive at their decisions," Dr. Abrams said. Each person conceptually weighs all of the individual features of LASIK and PRK as he or she understands them and uses his or her individual scoring system, which is a unique product of his or her history, to assign weights to the features and establish a preference.

One person's decision may seem wrong to someone else who is looking at the same data, but it is nonetheless legitimate if it has been well considered. If the second person wishes to change the other's decision, he or she must either provide different data or somehow change the first person's scoring system, he said.

He also suggested that preferences for LASIK or surface procedures may be in a state of flux and described an online, confidential private preference poll of refractive surgeons he conducted that when repeated annually would track the changes. In this survey, he confidentially asked these extremely well-informed doctors to assume the role of a 50-year-old patient with –4 D spherical myopia and select whether they would have a surface procedure or LASIK. This survey by design should be able to invoke each surgeon's most "genuine" scoring system, he said. He found that 50% chose LASIK, 35% chose surface ablation, and 10% chose neither procedure. The remaining 5% chose phakic lens implants or refractive lens exchange for themselves.

In contrast, a market survey of trends in refractive surgery showed that in 2006, 15% of patients had PRK and 85% had LASIK. The reason for the discrepancy in preferences for either procedure between Dr. Abrams' poll and the market data is unclear. Although some clinicians interpret it as evidence of a trend toward PRK, Dr. Abrams said that he found that conclusion unwarranted because of the disparate approaches of the two surveys.

The choice of procedure may be based on factors unrelated to the specific behavior of the flap, Dr. Abrams also said. Such differentiating factors may be related to surgical training, the intraoperative experience, the surgical recovery experience, and long-term outcomes.

The individual weights can sometimes be products of "emotional baggage" and may even appear irrational. Acute awareness of recent malpractice verdicts in malpractice cases involving post-LASIK ectasia could temporarily affect the surgeon's comfort level and choice, for example. Or perhaps an extremely vocal patient in the waiting room expressed a strong preference for one type of procedure and influenced others, or a surgeon who has been an "evangelist" for PRK would find it embarrassing to recommend lamellar procedures, Dr. Abrams said.

While he prefers to perform LASIK, rather than PRK, using a femtosecond laser and following careful candidate screening principles, he emphasized that PRK can be the clear choice for other surgeons who look at exactly the same data.

"We're only looking at the end product of an entirely unique deliberation by each patient and surgeon," he said.

Given the many factors that could be involved, the decision is very complex, Dr. Abrams said. He concluded his presentation by offering a fundamental principle that applies to both patients and surgeons. It states that at a given moment, for a given surgeon and a given patient, with fully defined LASIK and PRK procedures and informed personalized weighing of the data, there can never be an "illegitimate" choice, regardless of the outcome.

Dr. Shahinian took a firm position that both procedures are safe but that surface ablation is safer than LASIK and outlined the comparative risks. With surface ablation, risks include postoperative corneal haze and, in rare cases, ectasia. However, ectasia is the most significant risk associated with lamellar surgery; others include buttonholes, decentered ablations, lost flaps, traumatic flap dislocation, striae, epithelial ingrowth, optic atrophy, diffuse lamellar keratitis (DLK) and late DLK, persistent dry eye, and pressure-induced interlamellar keratitis.

There is a trend toward thinner flaps made with a femtosecond laser, but these flaps, too, carry a risk. Any time you make a lamellar flap, I think you have a greater risk of ectasia."

He added that it is too soon to tell whether these thin flaps made with the femtosecond laser will eliminate or reduce the rate of ectasia.

Data show that surface procedures are becoming more common, Dr. Shahinian continued. Data from a market survey organization showed that in 2001, only 3.6% of refractive procedures were surface ablations while 92.3% were LASIK. By 2005, the number of surface ablations had increased to 9.6% versus 86.7% LASIK, and the 2007 data showed that surface procedures accounted for 16.3% and LASIK 80.9%.

This surge in popularity of surface ablations is apparently due to the perception among both physicians and patients that they are safer because there is no possibility of flap complications, Dr. Shahinian said. He added that surgeons owe their patients an accurate and balanced explanation of the pros and cons of both surface and lamellar procedures.

"What should we tell our patients? First, the long-term visual results are essentially the same for the two procedures. Second, LASIK has distinct advantages in terms of early postoperative comfort and rapid vision recovery," Dr. Shahinian said. "However, and that's a big however, while LASIK and surface ablation are both safe, surface ablation is safer. As surgeons, we should ask ourselves if we're giving our patients all this information."