title: Oxygen and glucose distribution after intracorneal lens implantation.
abstract: OBJECTIVE
  Insertion of an implant in the cornea to achieve corneal multifocality has been suggested as a solution for presbyopia. However, unresolved issues related to nutrient transport need to be resolved. Our aim was to find the best lens position and influence lens transport properties in order to optimize nutrient supply to corneal cells.
  
  
  METHODS
  An axisymmetric corneal model was built to simulate the nutrient transport in the cornea. Oxygen and glucose concentrations were calculated for normal cornea and intracorneal lens wearing conditions. The simulation considers the different tissue layers (epithelium, stroma, and endothelium) as well as layer and solute concentration dependent consumption.
  
  
  RESULTS
  The minimum oxygen tension in the cornea was found to be higher when the lens was placed at 3/4 of the corneal thickness. Moreover, in this position, the influence of the inlay diffusivity was smaller than at more anterior or posterior placements. The diffusivity of the inlay affects the way nutrients will be transported through the cornea. The threshold where glucose may diffuse through or around the implant was found to be 1/100th of the stromal diffusivity.
  
  
  CONCLUSIONS
  Computational methods are especially attractive to study nutrient transport in the cornea due to the difficulties associated with in vivo or in vitro measurements. The exact parameters that dictate the corneal metabolism are not known. However, the combined analysis of oxygen and glucose distribution is valuable in order to predict the complex physiological changes that arise under intracorneal lens implantation.
authors: MEM Research Center, University of Bern, Bern, Switzerland. xabier.larrea@MEMcenter.unibe.ch
authors: Xabier
authors: X
authors: Larrea
authors: Christian
authors: C
authors: De Courten
authors: Vladimir
authors: V
authors: Feingold
authors: Jürgen
authors: J
authors: Burger
authors: Philippe
authors: P
authors: Büchler
mesh_terms: D001082:Aqueous Humor / Q000378:metabolism; D001693:Biological Transport, Active / Q000502:physiology; D003198:Computer Simulation; D003315:Cornea / Q000378:metabolism* / Q000601:surgery*; D020342:Finite Element Analysis; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism*; D011305:Presbyopia / Q000601:surgery; D019919:Prosthesis Implantation / Q000379:methods*
chemical_list: D005947:Glucose; D010100:Oxygen