Correlation Analysis Of Bowman’S Layer Microdistortions And Corneal Biomechanics Changes Evaluated By Brillouin Microscopy After Klex

To investigate the correlations between Bowman’s layer microdistortions and the changes of corneal biomechanics evaluated by Brillouin microscopy after Keratorefractive Lenticule Extraction (KLEx)

Eye & ENT Hospital of Fudan University, Shanghai, China.

This study included forty-three right eyes undergoing KLEx, with mean spherical equivalent of -5.89 ± 1.44 diopters. Metric M was calculated to indicate the quantity of Bowman’s layer microdistortions according to the images measured by Fourier-domain optical coherence tomography (FD-OCT) 1month postoperatively. Corneal biomechanical metrics were obtained and analyzed by Brillouin microscopy preoperatively and 1 month postoperatively.

Bowman’s layer microdistortions were observed using FD-OCT 1 month postoperatively, revealing a total width 502 (175, 698) μm of four meridians. Central, mean, minimum (Min), maximum (Max), and spatial standard deviation (SSD) Brillouin modulus (BM) quantified by Brillouin microscopy were 2.888 ± 0.074 GPa, 2.878 ± 0.041 GPa, 2.783 ± 0.059 GPa, 2.956 ± 0.053 GPa, 0.217 ± 0.063 GPa before KLEx, respectively; these changed to 2.800 ± 0.058 GPa (P<.001), 2.821 ± 0.033 GPa (P<.001), 2.734 ± 0.040 GPa (P<.001), 2.908 ± 0.051 GPa (P<.001), 0.223 ± 0.062 GPa (P =.666) 1 month after KLEx, respectively. Metric M was correlated with value’s changes of Mean BM (r =0.57, p<.001*) and Min BM (r =0.35, p=.02), controlling for spherical equivalent.

In this study, the alternations in corneal biomechanics following KLEx are positively correlated with the range of Bowman’s layer microdistortions. Increased Bowman’s layer microdistortions may lead to a more pronounced decline in corneal biomechanics.