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Correlation Analysis of Bowman's Layer Microdistortions and Corneal Biomechanics Changes Evaluated by Brillouin
Chi Zhang1,2, Xinyi Quan3, Xiaojun Hu1,2
1Ophthalmic Department, EYE & ENT Hospital of Fudan University, Shanghai, People's Republic of China.
Purpose:
To investigate the correlation between Bowman's layer microdistortions and the changes in corneal biomechanics evaluated by Brillouin microscopy after Keratorefractive Lenticule Extraction (KLEx).
Methods:
This study included forty-three right eyes that underwent KLEx, with a mean spherical equivalent of -5.89 ± 1.44 diopters. Metric M, the total width of the microdistortions, was calculated to indicate the quantity of Bowman's layer microdistortions according to the images measured using Fourier-domain optical coherence tomography (FD-OCT) 1month postoperatively. Corneal biomechanical metrics were obtained and analyzed using Brillouin microscopy preoperatively and 1 month postoperatively.
Results:
Bowman's layer microdistortions were observed using FD-OCT one month postoperatively, revealing a total width of 502 (175, 698) μm of the 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 <0.001), 2.821 ± 0.033 GPa (P <0.001), 2.734 ± 0.040 GPa (P <0.001), 2.908 ± 0.051 GPa (P <0.001), 0.223 ± 0.062 GPa (P =0.666) 1 month after KLEx, respectively. Metric M was correlated with value's changes of Mean BM (r =0.57, P <0.001*) and Min BM (r =0.35, P =0.02), controlling for spherical equivalent.
Conclusion:
In this study, the alterations 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 the corneal biomechanics. These findings may be useful for evaluating KLEx outcomes, detecting complications early, and optimizing patient monitoring.
