title: Reversible femtosecond laser-assisted myopia correction: a non-human primate study of lenticule re-implantation after refractive lenticule extraction.
abstract: LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap. Correction of refractive error is achieved by the resulting change in the curvature of the cornea and is limited by central corneal thickness, as a thin residual stromal bed may result in biomechanical instability of the cornea. A recently developed alternative to LASIK called Refractive Lenticule Extraction (ReLEx) utilizes solely a femtosecond laser (FSL) to incise an intrastromal refractive lenticule (RL), which results in reshaping the corneal curvature and correcting the myopia and/or astigmatism. As the RL is extracted intact in the ReLEx, we hypothesized that it could be cryopreserved and re-implanted at a later date to restore corneal stromal volume, in the event of keratectasia, making ReLEx a potentially reversible procedure, unlike LASIK. In this study, we re-implanted cryopreserved RLs in a non-human primate model of ReLEx. Mild intrastromal haze, noted during the first 2 weeks after re-implantation, subsided after 8 weeks. Refractive parameters including corneal thickness, anterior curvature and refractive error indices were restored to near pre-operative values after the re-implantation. Immunohistochemistry revealed no myofibroblast formation or abnormal collagen type I expression after 8 weeks, and a significant attenuation of fibronectin and tenascin expression from week 8 to 16 after re-implantation. In addition, keratocyte re-population could be found along the implanted RL interfaces. Our findings suggest that RL cryopreservation and re-implantation after ReLEx appears feasible, suggesting the possibility of potential reversibility of the procedure, and possible future uses of RLs in treating other corneal disorders and refractive errors.
authors.affiliation: Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore. andri_riau@yahoo.com
authors.forename: Andri K
authors.initials: AK
authors.lastname: Riau
authors.forename: Romesh I
authors.initials: RI
authors.lastname: Angunawela
authors.forename: Shyam S
authors.initials: SS
authors.lastname: Chaurasia
authors.forename: Wing S
authors.initials: WS
authors.lastname: Lee
authors.forename: Donald T
authors.initials: DT
authors.lastname: Tan
authors.forename: Jodhbir S
authors.initials: JS
authors.lastname: Mehta
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D018821:CD18 Antigens / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D003319:Corneal Stroma / Q000473:pathology / Q000601:surgery*; D005137:Eye, Artificial; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D019394:Ki-67 Antigen / Q000378:metabolism; D054018:Lasers, Excimer; D008251:Macaca / Q000601:surgery*; D009216:Myopia / Q000601:surgery*; D019919:Prosthesis Implantation; D012031:Refractometry; D019063:Tenascin / Q000378:metabolism; D013997:Time Factors; D041623:Tomography, Optical Coherence
chemical_list: D000199:Actins; D018821:CD18 Antigens; D024042:Collagen Type I; D005353:Fibronectins; D019394:Ki-67 Antigen; D019063:Tenascin