Corneal Collagen Cross-linking Combined With Simulation of Femtosecond Laser–Assisted Refractive Lens Extraction

Kanellopoulos, Anastasios John; Kontos, Mark A.; Chen, Shihao; Asimellis, George

doi:10.1097/ico.0000000000000376

Cited by 9 publications

(4 citation statements)

References 35 publications

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“…The corneal samples had no statistically significant age, gender, or race difference; the operations were designed in a way they would reflect current clinical standards in our practice: the upper lamellar dissection in SMILE was created at 140 µm, and the femtosecond LASIK flap was created at 110 µm, exactly as in our clinical practice. To evaluate the effect on corneal biomechanical properties, we used biaxial stress–strain measurements, 27 , 28 which may be superior to corneal strip extensiometry used in earlier experiments considering the nonuniform topographic distribution of the corneal strength profile. 29 , 30 Thus, the orientation of the cornea specimens during the tensile measurements was intentionally random, to exactly address the fact that the in-plane biomechanical properties may naturally vary along different corneal meridians because of the known anisotropic differences of corneal collagen.…”

Section: Discussionmentioning

confidence: 99%

Comparison of corneal biomechanics after myopic small-incision lenticule extraction compared to LASIK: an ex vivo study

Kanellopoulos¹

2018

OPTH

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PurposeTo investigate ex vivo potentially different corneal biomechanical properties after small-incision lenticule extraction (SMILE) versus LASIK for myopic correction.MethodsThirty human donor corneas were subjected to either myopic SMILE or femtosecond laser-assisted LASIK. Donor corneas were assigned to six investigative groups: Group A, −3.00 D (diopters) SMILE; Group B, −8.00 D SMILE; Group C, −3.00 D LASIK; and Group D, −8.00 D LASIK. Additionally, two control groups were formed: Group E, SMILE and Group F, LASIK. All groups consisted of five corneas, randomly allocated. The corneas in the control groups were subjected to the corresponding femtosecond-laser lamellar cuts but not to tissue removal. Evaluation of biomechanical tensile strength was conducted by biaxial force application. Primary outcome measures were stress at 10% and 15% strain, and Young’s modulus at 10% and 15% strain.ResultsIn SMILE, the average relative difference (Δ) of the four outcome measures was −34.46% for −3.00 D correction versus control Group E and −49.34% for −8.00 D correction versus control Group E. In LASIK, average Δ was −24.88% for −3.00 D correction versus control, and −52.73% for −8.00 D correction versus control. All these differences were statistically significant; SMILE compared to LASIK for the same myopic correction appears to result in more biomechanical reduction for −3.00 D corrections by −26%, while a nonstatistically significant difference was noted in −8.00 D corrections.ConclusionBoth SMILE and LASIK procedures do substantially alter corneal biomechanical properties, and the degree of tensile strength reduction is statistically significantly correlated to the extent of myopic correction. Additionally, SMILE procedure seems to result in more tensile strength reduction in lower myopic corrections compared to LASIK, and similar tensile strength reduction to LASIK in higher myopic corrections when compared to LASIK.

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Section: Discussionmentioning

confidence: 99%

Comparison of corneal biomechanics after myopic small-incision lenticule extraction compared to LASIK: an ex vivo study

Kanellopoulos¹

2018

OPTH

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“…A limitation of the current work was unable to perform direct biomechanical measurements due to limited resources. Nevertheless, it had been shown that direct in vivo measurement of the corneal biomechanical property had low specificity and sensitivity [ 32 ]. The slight myopic shift demonstrated in our SMILE Xtra group could as well be due to an inadequate CXL effect to strengthen the cornea of our SMILE Xtra cases (where the preoperative corneas are thinner).…”

Section: Discussionmentioning

confidence: 99%

“…The slight myopic shift demonstrated in our SMILE Xtra group could as well be due to an inadequate CXL effect to strengthen the cornea of our SMILE Xtra cases (where the preoperative corneas are thinner). The strengthening effects of SMILE Xtra have been supported by an ex vivo study on human cornea by Kanellopoulos et al, which showed that combining cross-linking with refractive lenticule (5 mm diameter and 80 μ m thickness at 140 μ m depth) extraction resulted in significantly increased biomechanical properties compared with control non-cross-linked eyes [ 32 ]. We did not routinely check the endothelial cell count either, as it has already been shown that there was no significant change in the endothelial cell count before and after SMILE [ 33 ] or in SMILE Xtra [ 28 ].…”

Section: Discussionmentioning

confidence: 99%

Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia

Chan

Cheng

et al. 2016

Journal of Ophthalmology

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Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra) with SMILE. Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively. Results. Both groups had myopia with spherical equivalent refraction (SEQ) > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p < 0.021). At 6 months, no eyes lost more than 1 line in corrected distance visual acuity. The safety index was 0.96 ± 0.06 and 1.00 ± 0.00 in SMILE Xtra and control, respectively (p < 0.001). 89% and 94% of eyes were within ±0.50 D of target refraction, respectively, with the mean error in SEQ correction being −0.17 ± 0.26 D for SMILE Xtra and +0.03 ± 0.25 D for control (p = 0.021). The efficacy index was 0.88 ± 0.13 and 0.97 ± 0.06, respectively (p = 0.005). Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

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“…Biaxial stress–strain measurements were superior to corneal strip tensiometry. − Previous studies have also shown that sclera exhibited a stress-hardening response when subjected to gradual tensile loads, demonstrating nonlinear characteristics. , The present study also indicated that the sclera is elastic and exhibits an obvious hysteresis phenomenon. This further indicates that the whole sclera exhibits major mechanical anisotropy.…”

Section: Discussionmentioning

confidence: 99%

Application of Decellularized Porcine Sclera in Repairing Corneal Perforations and Lamellar Injuries

Sun

Qiao

Zhao

et al. 2022

ACS Biomater. Sci. Eng.

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Scleras are mainly used for the treatment of glaucoma, eyelid damage, and scleral ulcers. Given that the sclera and cornea collectively constitute the complete external structure of the eyeball and both have the same tissue and cell origin, we attempted to identify scleral materials to treat lamellar and penetrating corneal injuries. Based on research in our center, antigenic components in decellularized porcine sclera (DPS) were removed using a simplified decellularization method, leaving the collagen structure and active components undamaged. DPS preserved the mechanical properties and did not significantly inhibit the proliferation and replication of human corneal epithelial cells. In vivo, the graft epithelium healed well after lamellar and penetrating scleral grafting, and the graft thickness did not change evidently. DPS can resist suture traction during scleral transplantation and maintain anterior chamber stability until day 28 post-operatively, especially in penetrating repairs. No obvious immune rejection of lamellar or penetrating scleral grafts was found 28 days after DPS transplantation. This study shows that DPS could be used as an alternative material for the emergency repair of corneal perforations and lamellar injuries, representing another application of sclera.

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Corneal Collagen Cross-linking Combined With Simulation of Femtosecond Laser–Assisted Refractive Lens Extraction

Abstract: Adjunct CXL in this ex vivo simulation refractive lens extraction procedure seems to provide significant increase in corneal rigidity, up to +107%. These findings also support our previous reported work on laser in situ keratomileusis combined with CXL.

Cited by 9 publications

References 35 publications

Comparison of corneal biomechanics after myopic small-incision lenticule extraction compared to LASIK: an ex vivo study

Comparison of corneal biomechanics after myopic small-incision lenticule extraction compared to LASIK: an ex vivo study

Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia

Application of Decellularized Porcine Sclera in Repairing Corneal Perforations and Lamellar Injuries

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