The risk of sight-threatening corneal ectasia after thin-flap LASIK appears very low, according to a new study.
A retrospective review of 2,000 eyes treated with all-laser LASIK using an IntraLase femtosecond laser to create an extra-thin corneal flap, only one case of central corneal ectasia was reported.
The laser-created flaps in all cases were designed to be 90 microns thick. By comparison, conventional microkeratome-created LASIK flaps in the past have frequently been 160 microns or thicker (though modern bladed microkeratomes are capable of creating thinner flaps as well.)
The one case of post-LASIK ectasia in the study was reported six months after surgery. Patients in the study were monitored for up to three years after the thin-flap LASIK procedure.
Corneal ectasia after LASIK
Corneal ectasia is an apparently rare but serious LASIK complication. It is characterized by an irregular outward bulging of the cornea similar to the eye disease keratoconus.
One possible risk factor for ectasia is failure to leave adequate corneal thickness under the flap created in LASIK surgery to preserve the biomechanical strength and stability of the cornea.
Because of this potential, many refractive surgeons in recent years have chosen to create thinner corneal flaps during the LASIK procedure to preserve greater corneal thickness under the flap.
Though there are promising new treatments for corneal ectasia, the condition can cause permanent vision loss. In severe cases, a corneal transplant may be required to restore vision.
Careful pre-operative screening is key to ectasia prevention
Experts agree that careful pre-operative screening of patients can reduce the risk of post-LASIK ectasia. Corneal topography measurements often can identify patients who may have signs of subclinical keratoconus or other corneal abnormalities and therefore are not good candidates for laser vision correction surgery.
In the current study, investigators re-examined the pre-operative corneal topography measurements of the one patient who developed post-LASIK ectasia and found signs of subclinical keratoconus.
Post-LASIK ectasia: conclusions
Nader Robin, MD, presented the results of the study at the annual meeting of the European Society of Cataract and Refractive Surgeons (ESCRS) held this week in Barcelona, Spain.
Though only one case of ectasia was noted in the study, Dr. Robin said post-LASIK ectasia can occur months or even years after surgery and therefore longer follow-up studies are needed to draw more reliable conclusions about the risks of ectasia after LASIK.
SOURCE: Thin-flap LASIK with femtosecond laser may help avoid iatrogenic ectasia. Ocular Surgery News website (OSNsupersite.com). September 18, 2009.
Tags: complications, cornea, Ectasia