Permanent Loss of Corneal Biomechanical Strength After LASIK
Intraocular pressure inside the eye pushes constantly against the back surface of the cornea. In a healthy eye, the collagen bands of the cornea provide support to withstand these forces. LASIK surgery involves cutting a corneal flap, which severs collagen bands that never reconnect. After creation of the flap, the surgeon uses a laser to remove corneal tissue, further thinning the cornea. Together, flap creation and laser ablation reduce stress-bearing thickness of the cornea, leaving the cornea permanently weakened.
Post-LASIK keratectasia (ectasia) is a rare, sight-threatening complication of LASIK in which the weakened cornea begins to bulge forward in response to the pressure inside the eye. When this occurs, vision deteriorates progressively. Ectasia usually occurs within weeks or months of LASIK, but may occur several years after seemingly uneventful LASIK. (1)
Reported risk factors for post-LASIK corneal ectasia include abnormal corneal topography, low residual stromal bed thickness, young patient age, low preoperative corneal thickness, and high myopia. (2) The FDA website warns, "Performing a refractive procedure on a cornea that is too thin may result in blinding complications." (3)
Treatment modalities for post-LASIK ectasia include rigid gas permeable contact lenses (RGPs) and corneal transplantation. Clinical trials of corneal collagen cross-linking with riboflavin/UVA light to treat corneal ectasia are underway. Learn more about the clinical trial.
The true rate of post-LASIK ectasia is unknown. Due to the fear of ectasia, some surgeons have stopped performing LASIK.
- Lifshitz T, Levy J, Klemperer I, Levinger S. Late bilateral keratectasia after LASIK in a low myopic patient. J Refract Surg. 2005 Sep-Oct;21(5): 494-6.
- Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology 2008;115:37–50