ABSTRACT
PURPOSE: To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK). SETTING: Beyoglu Eye Training and Research Hospital. DESIGN: Prospective comparative case series. METHODS: Sixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10diopters (D) and a difference ≤0.50D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months). RESULTS: Preoperative SE was similar in both groups (p=0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p<0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95±1.47 and 9.02±1.27, respectively (p=0.852), and the mean CRF values were 7.77±1.37 and 8.07±1.26, respectively (p=0.380). CONCLUSION: CH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values.
Subject(s)
Cornea/physiopathology , Cornea/surgery , Keratomileusis, Laser In Situ/methods , Minimally Invasive Surgical Procedures/methods , Myopia/physiopathology , Myopia/surgery , Refractive Surgical Procedures/methods , Adult , Corneal Topography , Elasticity , Female , Hardness , Humans , Male , Myopia/diagnosis , Prospective Studies , Treatment Outcome , ViscosityABSTRACT
PURPOSE: To compare the topographic and biomechanical properties of corneas in eyes of patients with ichthyosis vulgaris (IV) and eyes of healthy individuals. METHODS: Thirty healthy individuals (control group) and 30 patients with IV (study group) were enrolled in this prospective study. Topographic measurements, including keratometry values, irregularity, and surface asymmetry index in the right eye of each participant were obtained using Scheimpflug camera with a Placido disc topographer (Sirius). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldman-related intraocular pressure (IOPg) were measured using the Reichert Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was also measured with ultrasonic pachymetry and the Sirius corneal topography system. RESULTS: Topographic parameters were not significantly different between both groups (p>0.05). Although mean CH was not significantly different between the groups, the CRF was significantly lower in patients with IV (p=0.249 and p=0.005, respectively). The CCT was significantly lower in patients with IV compared to healthy controls (p<0.001). The IOPg and IOPcc were significantly lower in the patients with ichthyosis than in healthy controls (p=0.001 and p=0.004, respectively). CONCLUSIONS: The study demonstrated that while the eyes of patients with IV had corneal topographic findings and corneal hysteresis similar to those of healthy controls, some of corneal biomechanical properties such CRF and CCT and IOP values such as IOPg and IOPcc were significantly lower in patients with IV. These results should be taken into account when planning a corneal refractive surgery and glaucoma screening for patients with IV.
