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. 2017 Jan 17;16(1):20.
doi: 10.1186/s12938-017-0311-5.

Effects of ablation depth and repair time on the corneal elastic modulus after laser in situ keratomileusis

Xiaojun Wang  1 , Xiaona Li  2 , Weiyi Chen  3 , Rui He  4 , Zhipeng Gao  1 , Pengfei Feng  1
Affiliations

Effects of ablation depth and repair time on the corneal elastic modulus after laser in situ keratomileusis

Xiaojun Wang et al. Biomed Eng Online. .

Abstract

Background: The biomechanical properties of the cornea should be taken into account in the refractive procedure in order to perform refractive surgery more accurately. The effects of the ablation depth and repair time on the elastic modulus of the rabbit cornea after laser in situ keratomileusis (LASIK) are still unclear.

Methods: In this study, LASIK was performed on New Zealand rabbits with different ablation depth (only typical LASIK flaps were created; residual stroma bed was 50 or 30% of the whole cornea thickness respectively). The animals without any treatment were served as normal controls. The corneal thickness was measured by ultrasonic pachymetry before animals were humanly killed after 7 or 28 days post-operatively. The corneal elastic modulus was measured by uniaxial tensile testing. A mathematical procedure considering the actual geometrics of the cornea was created to analyze the corneal elastic modulus.

Results: There were no obvious differences among all groups in the elastic modulus on after 7 days post-operatively. However, after 28th days post-operatively, there was a significant increase in the elastic modulus with 50 and 30% residual stroma bed; only the elastic modulus of the cornea with 30% residual stroma bed was significantly higher than that of 7 days.

Conclusions: Changes in elastic modulus after LASIK suggest that this biomechanical effect may correlate with the ablation depth and repair time.

Keywords: Ablation depth; Cornea; Elastic modulus; LASIK; Repair.

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Figures

Fig. 1
Fig. 1
LASIK surgery was performed on a rabbit a under anaesthesia, b creating the flap, c lifting the flap, d ablating the stroma, e restoring the flap, f surgery finished
Fig. 2
Fig. 2
Evaluation of biomechanical properties of corneal strips was carried out on Instron 5544 tester
Fig. 3
Fig. 3
The load–displacement curve of a corneal strip
Fig. 4
Fig. 4
A diagram of the corneal strip after LASIK against an X–Y coordinate system
Fig. 5
Fig. 5
Effects of variation in ablation depth on the corneal elastic modulus after LASIK. *P < 0.05, compared to normal control after 28 days post-operatively; #P < 0.05, compared to group 1 after 28 days post-operatively. n = 10 in each group
See this image and copyright information in PMC

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