Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: A prospective fellow eye study

Small-incision lenticule extraction

“…Corneal hysteresis (CH) and the corneal resistance factor (CRF) are parameters that have been used to measure and characterize relative corneal biomechanical strength. 62 In a study by Agca et al, 37 comparison of postoperative parameters in small-incision lenticule extraction and femtosecond-assisted LASIK did not demonstrate significant differences in CH or CRF. In contrast, a study by Wu et al 63 found a statistically significant elevation in CH and CRF in small-incision lenticule extraction compared with femtosecond laser-assisted LASIK.…”

“…Conventional parameters used during small-incision lenticule extraction are as follows: repetition rate 500 kHz, pulse energy 120 to 170 nJ, spot distance 2 to 5 mm, lenticule side-cut angle 70 degrees, lenticule diameter 5.75 to 7.00 mm, cap diameter 7.0 to 7.9 mm (typically 0.5 to 1.0 mm greater than the lenticule diameter), cap thickness 100 to 140 mm, side-cut circumferential length 3.0 to 5.0 mm, and minimum lenticule side-cut thickness 15 mm. [12][13][14][15]33,[35][36][37][38][39] The optical zone diameter is typically equivalent to the lenticule diameter when only spherical error is being corrected; a transitional zone is added for cylindrical corrections, altering the lenticular shape from ovoid to circular, with subsequent modification of the lenticule diameter. 36 The total time for all femtosecond laser-generated incisions is between 20 seconds and 35 seconds regardless of the refractive error magnitude.…”

Comparison of Corneal Biomechanical Characteristics After Surface Ablation Refractive Surgery and Novel Lamellar Refractive Surgery

“…[1][2][3] A recently developed technique called small-incision lenticule extraction (SMILE) has shown effectiveness for refractive correction of myopia and myopic astigmatism. 4 The safety and corneal sensitivity of SMILE have been demonstrated in several previous studies. [5][6][7] Characterized by a flapless and small-incision procedure, SMILE causes less corneal biomechanical damage than other types of refractive surgeries, such as laser-assisted in situ keratomileusis (LASIK) and femto-LASIK (femtosecond laser-assisted in situ keratomileusis), which involve flap creation.…”

All-Femtosecond Laser Keratorefractive Surgery

“…At present, only one study has been published on the biomechanical properties after ReLEx smile in comparison with FS-LASIK using the Ocular Response Analyzer [38]. This paired-eye, randomized study found no differences in corneal hysteresis (CH) or corneal resistance factor (CRF) 6 months after surgery.…”