title: Clinical, Refractive and Histological Reversibility of Corneal Additive Surgery in Deep Stroma in an Animal Model.
abstract: The aim was to evaluate the reversibility of the clinical and histological changes induced in the corneas of an animal model after removing an intracorneal ring segment (ICRS).
  
  
  
  Surgery for this study was performed in 38 eyes of an experimental animal model (Gallus domesticus) for ICRS surgery (Ferrara technique). The animals without complications were randomized to two groups; in all of them, 1 segment was implanted in each eye and later removed at different times (1 and 3 months after implantation). In each group, after explantation, corneas were processed at different times for histological analysis with hematoxylin and eosin (H&E) stain and electronic microscopy. The refractive state of the eyes was also measured.
  
  
  
  In corneas without complications (88.23%), explantation was performed correctly. During the first few days, around the area where the ICRS was implanted we observed deposits of cells and a moderate degree of corneal opacity (haze). These signs decreased progressively without disappearing completely. Histologically, at 7 days, we observed hyperplasia and abnormal arrangement of collagen fibers. Later, these findings also decreased in both groups, albeit at a faster rate in group 1. Minimal changes were observed in electron microscopy up to the end of the study in both groups. Preoperative refractive state was achieved at 1 month after explantation in both groups.
  
  
  
  ICRS can safely be explanted from the cornea. Refractive reversibility was achieved at 1 month after explantation. However, the clinical and histological findings after ICRS explantation depend on the time from implantation to explantation.
authors.affiliation: a Optical Diagnostic Techniques Group, Theoretical, Atomic and Optical Physics Department , University of Valladolid , Valladolid , Spain.|b Ophthalmology Department , Hospital Clínico Universitario de Valladolid , Valladolid , Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: Ibares-Frías
authors.affiliation: a Optical Diagnostic Techniques Group, Theoretical, Atomic and Optical Physics Department , University of Valladolid , Valladolid , Spain.|c Cell Biology, Histology and Pharmacology Department , Faculty of Medicine, University of Valladolid , Valladolid , Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Gallego
authors.affiliation: c Cell Biology, Histology and Pharmacology Department , Faculty of Medicine, University of Valladolid , Valladolid , Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Cantalapiedra-Rodriguez
authors.affiliation: a Optical Diagnostic Techniques Group, Theoretical, Atomic and Optical Physics Department , University of Valladolid , Valladolid , Spain.|d Instituto Universitario Fernandez-Vega, Universidad de Oviedo , Oviedo , Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Merayo-Lloves
authors.affiliation: a Optical Diagnostic Techniques Group, Theoretical, Atomic and Optical Physics Department , University of Valladolid , Valladolid , Spain.|c Cell Biology, Histology and Pharmacology Department , Faculty of Medicine, University of Valladolid , Valladolid , Spain.
authors.forename: María Carmen
authors.initials: MC
authors.lastname: Martínez-García
mesh_terms: D000818:Animals; D002645:Chickens; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000473:pathology / Q000601:surgery*; D019781:Corneal Topography; D004195:Disease Models, Animal; D007640:Keratoconus / Q000150:complications / Q000473:pathology / Q000601:surgery*; D009216:Myopia / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D013508:Ophthalmologic Surgical Procedures / Q000379:methods*; D019919:Prosthesis Implantation / Q000379:methods*; D012029:Refraction, Ocular / Q000502:physiology*; D016896:Treatment Outcome; D014792:Visual Acuity
keywords: Additive surgery; corneal wound healing; intrastromal corneal ring segments; keratoconus; reversibility