الفهرس | Only 14 pages are availabe for public view |
Abstract Corneal refractive surgery is the most performed ophthalmic procedure in the world. Despite the huge leaps in advancing this technology to reduce the risks of intraoperative and postoperative complications, there is still a very small risk to develop sight threatening complication such as cornea ectasia. Corneas at risk of ectasia are usually thinner with abnormal topographies, but some normal thin corneal with normal topographies have developed ectasia, a distinction sometimes hard to make between myopia with such corneas and subclinical cases of keratoconus or forme frust keratoconus. The Oculus Corvis ST (Oculus Optikgeräte, OCULUS, Wetzlar, Germany) is a noncontact High-Speed (UHS ST) tonometer, supported by Scheimpflug Technology, designed to obtain in vivo measurements of corneal biomechanical properties; this device allows monitoring corneal deformation response to a symmetrically metered air pulse. This biomechanical study should not be used as the sole test to detect the suitability of the eyes for refractive surgery but as an adjunct to the clinical and topographical test. This is a small prospective clinical interventional series study carried out from March 2016 to April 2017 on 50 eyes of 28 patients were equally divided in to two groups; group I underwent wavefront optimized LASIK procedure and group II underwent femto SMILE procedure. We studied corneal biomechanics before and three month after refractive surgery. In our study the average of age is 25.31±3.56 ranging (20-38) years in group I and26.84±3.72 ranging (21-36) years in group II . The average of treated MRSE was -5.47±1.16 ranging (from -4.0 to -7.75) diopter in group I, and The average of treated MRSE was -5.52±1.14 ranging (from -4.0 to -8.5) diopter in group II. The average of the preoperative central cornea thickness was 524.97±16.35 ranging (506- 567) μm in group I,and The average of the pre-operative central cornea thickness was 531.62±16.22 ranging (513-603) μm in group II .The average of tissue ablated is 68.5±22.1 ranging (41-89) μm in group I ,and The average of lenticule thickness is 70.3±19.8 ranging (52-98) μm in group II. The preoperative values of deformation amplitude was within normal ranges in all patients. |