Background: hysteresis refers to the energy lost during the stress/strain cycle which is the result of viscous damping in the corneal tissue, is an indicator of corneal biomechanical properties. Refractive surgery currently uses corneal thickness as a basic qualification and planning parameter. However, corneal hysteresis may be more useful as a qualification factor for LASIK, a significant decrease in the IOP and biomechanical properties is found in eyes following LASIK surgery
Objective: this study aimed to reveal the variations of corneal hysteresis in patients with normal pentacam findings and to see if a correlation exists between corneal hysteresis, corneal resistance factor, mean keratometric reading, central corneal thickness and anterior chamber depth during the pre-operative assessment of myopic patients going for LASIK.
Patients and methods: in this study we did an analysis of corneal hysteresis in a group of myopic patients with normal pentacam findings undergoing evaluation for refractive surgery. In our study we included 50 eyes of 26 patients aged between 18 and 44.Results: this study included a mean keratometric reading of 44.108 D± 1.3243D, the mean central corneal thickness was 522.1um±38.416um, the mean anterior chamber depth was 3.2098mm±0.249mm the mean corneal hysteresis was 9.582 mmHg±1.4702 and the mean corneal resistance factor was 9.64 mmHg ±1.9838.Conclusion: our data suggested that patients should get their corneal hysteresis tested as a part of their routine investigation portfolio before undergoing refractive surgery as it may play a role in determining patients that are at higher risk of developing ectasia after surgery.