[Investigation of the biomechanical properties of corneal lenticules in myopia and myopic astigmatism after femtosecond laser vision correction with the CLEAR technique].

PURPOSE: This study aimed to investigate the local mechanical properties and determine the Young's modulus (Y) of corneal lenticules (stromal layer fragments) using scanning ion-conductance microscopy (SICM) in patients with myopia and myopic astigmatism who underwent femtosecond laser surgery using the corneal lenticule extraction for advance refractive correction (CLEAR) technique.

MATERIAL AND

METHODS

The study included 19 patients aged 21-48 years, comprising 11 men (58%) and 8 women (42%) (38 eyes), from whom 34 lenticules were extracted. Participants were divided into two groups: group 1 - patients aged 26-36 years, and group 2 - patients aged 41-48 years. The analysis of extracted lenticules was performed 6-10 hours postoperatively. The preoperative, intraoperative, and postoperative parameters were as follows: spherical equivalent from -1.75 to -8.25 D, cylindrical component from -0.0 to -1.75 D, central corneal thickness 511-607 μm, lenticule thickness 78-159 μm, percentage of tissue altered (PTA) index 33.1-47.1, and posterior lenticule surface depth 288-402 μm.

RESULTS

In group 1, the Young's modulus values of stromal fibrils (at a depth of 302-402 μm) ranged from 128.7 to 920 Pa, whereas in group 2 (depth 288-377 μm), the values ranged from 252.2 to 641.1 Pa.

CONCLUSION

For the first time, the biomechanical properties of the fibrils in the middle stroma were studied in vivo and described using the Young's modulus. Elasticity was higher in the lenticules extracted from patients aged 21-36 years than in those from patients aged 41-48 years.