Three-Dimensional Modeling of Glucose and Oxygen Transport in Cornea With Hydrogel Intrastromal Inlay
Narrative Responses:
Purpose
To calculate changes in glucose concentration and oxygen tension in corneal tissue due to implantation of a RaindropTM Near Vision Inlay (RVO, Lake Forest, CA). Computational methods are required due to high experimental difficulty in making such measurements.
Methods
A computational model to simulate changes in glucose concentration and oxygen tension in corneal tissue after implantation of a hydrogel inlay has been created. A one-dimensional model proposed by Chhabra et al. in 2009 was extended to three dimensions to produce a model for cellular metabolism involving the coupled behavior of oxygen, glucose and lactate ions in a four-region (epithelium, stroma, endothelium, and inlay) representation of the cornea-inlay system. Finite element multiphysics modeling software COMSOL (Version 4.3, 2012) was used. The model was employed to evaluate sensitivity to changes in parameters such as corneal thickness and depth of implantation.
Results
Glucose, oxygen and lactate ion concentration profiles across the central corneal thickness were obtained for a normal cornea. An axisymmetric model of the inlay under a conforming 150 mm flap was then analyzed with known values for oxygen permeability and glucose diffusivity of the inlay. Concentration contours relative to the normal cornea were obtained for the three species. No depletion of more than 3.5% was calculated at any point in the cornea for oxygen concentration or glucose tension. Sensitivity to corneal thickness and depth of implantation made only small changes to the results.
Conclusion
The impact of the placement of this hydrogel inlay on metabolic species in the cornea is within expected variation from person to person and within the cornea of any individual. When functioning properly, the inlay is expected to have little or no impact on the metabolic functioning of the cornea.