Evaluation of the risk of corneal ectasia

Objective: LASIK is associated with a severe complication known as corneal ectasia. A direct evaluation of the biomechanical corneal property may be performed to select patients for excimer laser surgery. Methods: Detection of the biomechanical corneal properties was performed using a specific device known to produce short intraocular pressure elevation (IOP) at approximately 20 mm Hg. The cornea topographic method was performed twice: before and during IOP loading. Results: The patient, a 26-year-old female with myopia of both eyes, requested surgical correction of her myopia. IOP loading had caused extension and deformation of the cornea shape of both eyes. Normal eyes retain their shape under such conditions. We classified the biomechanical properties of both corneas as very weak and recommended the patient refrain from refractive surgery. Conclusions: Direct evaluation of the corneal biomechanical properties revealed potential in the selection of patients for excimer laser surgery. Introduction Laser in situ keratomileusis (LASIK) has become the gold standard in refractive surgery. After undergoing LASIK, pilots have begun to return to flight status in the United States [1]. Nevertheless, LASIK is associated with a severe complication known as corneal ectasia. This complication is of serious concern because patients undergo LASIK surgery with practically healthy eyes and have other options for vision correction. The methods used to estimate the risk of post-surgical ectasia have been well documented in the literature [2-4]. Despite good ability to predict this complication, current studies continue to report cases of iatrogenic keratectasia [5,6]. Here, we developed a new method, which is intended to evaluate a dynamic change of cornea shape under a condition of artificially elevated intraocular pressure (IOP) [7]. Distortion of the cornea occurs in case of a weakened corneal biomechanical property. The principle of ophthalmodinamometer (ODM) was applied. However, ODM causes meridional eyeball deformation, resulting in corneal astigmatism. Our instrument induces pressure via the circle element in the eyeball area behind the limbus. Such an approach enables the initial corneal shape to be secured. The stability of the cornea shape or its deformation serves as a basis for an evaluation of the cornea biomechanical property. The reported case presents the first attempt to use our method of direct examination of the corneal biomechanical property to indicate or contraindicate patients for excimer laser surgery. Case description The patient, a 26-year-old female with myopia of both eyes, requested surgical correction of her myopia. She received an invitation to undergo the surgical correction at a private clinic. The patient provided her informed consent on the examination. In addition to an anomaly of refraction, the patient’s medical history was unremarkable. At the time of examination, the manifest Correspondence to: Nikolai Sergienko, Eye Microsurgery Center, Komarov ave, 3, Kyiv, 03680, Ukraine, Tel: +38050 6886428, +38044 4080536; Fax: +38044 4044485; E-mail: [email protected]