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Muhammad Ahmad Khan, Ding Lin; The Study on Changes of Rabbit Corneal Biomechanical Properties after Femtosecond Assisted LASIK. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1392. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To discover the biomechanical changes of rabbit cornea in early recovery stage after FS-LASIK surgery.
Examine biomechanical parameters of normal rabbits through Ocular Response Analyzer (ORA) to know the reference value of biomechanical properties of normal rabbit. Perform FS-LASIK on the left eye of 18 rabbits to maintain the residual corneal thickness at 30%-45% of full thickness. All right eyes are taken as control. Observe post-operative data of CCT, IOP, CH and CRF. Perform in vitro uniaxial tensile test of half surgical rabbits at post-op 5th week, observe the changes of stress-strain curve, stress-relaxation curve and stress-tangent modulus curve of samples.
Reference range of ORA figures were 5.0-8.4mmHg of IOPcc, 11.9-14.9mmHg of IOPg, 2.4-4.8mmHg of CH and 4.2-6.0 mmHg of CRF. 14 rabbit corneas maintained well 4 weeks after surgery, CH and CRF had no change within post-op 4 weeks (P>0.05). 8 eyes of 4 rabbits maintained well after execution at post-op 5th week. Remaining alive 6 surgical eyes experienced significant increase in CH at post-op 6-10th week compared with pre-op data (P<0.05), and at post-op 8-10th week compared with post-op 4th week (P<0.05) as well. Difference of CRF was also significant at post-op 8-10th week, compared with post-op 2nd and 4th week (P<0.05). Result of uniaxial tensile test showed force of stress was larger at surgical eyes than controls under the same condition of strain, and strain was lesser at surgical eyes under the same force of stress, difference was not significant at the stress-relaxation curve between both groups (P>0.05). Tangent modulus was larger at control eye than surgical eye in sample K25 and K32, K26 and K30 showed the opposite.
Cornea biomechanical properties start to experience increase around 4th week after FS-LASIK surgery, CH and CRF increases significantly and under same strain, the stress of surgical eyes is higher than non-surgical eyes. Biomechanical property elevates when corneal self-repair process started after LASIK surgery.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
stress-strain curve & stress-relaxation curve of samples
Tangent Modulus of Samples
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