Ectasia is a recognized complication of LASIK in a minority of cases, but the degree of risk from pre-existing conditions remains largely unknown.
A preliminary analysis of a dataset containing more than 300,000 eyes treated with LASIK between 6 to 10 years ago is beginning to quantify some of the risks involved.
“This is the largest study of ectasia in a cohort of successive patients—361,848 eyes of 184,728 patients,” said Steven C. Schallhorn, MD, the initial principal investigator.
“Some of the early results are not surprising—specifically, that age and corneal shape are the dominant factors related to keratoconus after LASIK,” he said. “Other results were not quite what was expected.”
Dr. Schallhorn presented preliminary results on an ongoing analysis of a database created by Optical Express, the largest provider of refractive surgery in Europe. He launched the study as the chief medical director of Optical Express and oversaw the initial analysis. He currently maintains a private practice in San Diego, CA.
Refractive laser surgery is noted for its high rates of safety and patient satisfaction, but complications can, and do, arise. Within the entire cohort, ectasia was seen in 199 eyes of 146 patients during follow up, an incidence of about 0.055%.
Age and corneal shape before surgery have long been recognized as risk factors for ectasia. Because ectasia is such a rare complication, nearly all prior studies have been case-control.
Case-control studies can help to identify risk factors for rare conditions and infrequent complications, but cannot quantify risks, he noted.
“As clinicians, we want to know if a particular preoperative condition poses a risk for ectasia and, more importantly, the level of risk,” Dr. Schallhorn continued.
“If the chance of ectasia is 1:2,000 in the general population and a preoperative factor increases the risk to 1:1,900, it may be statistically significant but it is not very clinically relevant,” he said. “The goal of this study is to help quantify risk factors so that we can better select and counsel patients.”