Oxygen and glucose distribution after intracorneal lens implantation.
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.
Larrea
Xabier
X
MEM Research Center, University of Bern, Bern, Switzerland. xabier.larrea@MEMcenter.unibe.ch
De Courten
Christian
C
Feingold
Vladimir
V
Burger
Jürgen
J
Büchler
Philippe
P
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*
D005947:Glucose; D010100:Oxygen