Limbal Metabolic Support Reduces Peripheral Corneal Edema with Contact-Lens Wear

Abstract

To assess the influence of limbal metabolic support on corneal edema during scleral-lens (SL) and soft-contact-lens (SCL) wear for healthy lens wearers. Methods: A two-dimensional (2D) model of the cornea and sclera was designed on Comsol Multiphysics 5.4 along with SL and SCL architectures to mimic lens-wear induced hypoxia. The cornea is suffused with oxygen and metabolites from the limbus and aqueous humor. Air oxygen is supplied from and carbon dioxide is expelled to the atmosphere. Lens-oxygen permeability (Dk) was adjusted to investigate lens-wear safety against edema in different wear conditions. The 2D concentrations of oxygen, carbon dioxide, bicarbonate, lactate, sodium, chloride, glucose, and pH are quantified. Centralto-peripheral swelling of the cornea is determined by the change in stromal hydration caused by changing metabolite concentrations at the endothelium during hypoxia. Results: The metabolic model assesses central-to-peripheral corneal swelling with different types of lenses, and oxygen Dks. Limbal metabolic support reduces edema from the periphery to approximately 1 mm away from the central cornea. Despite thicker lens designs, the peripheral cornea exhibits practically zero swelling due to limbal metabolic support. Conclusions: The metabolic model accurately predicts central-to-peripheral corneal edema with various contact-lens designs, post-lens tear-film thicknesses, and lens oxygen Dk values. Despite the thicker periphery of most contact-lens designs, lactate and bicarbonate support from the limbus significantly reduces peripheral and midperipheral corneal edema, whereas oxygen has a lesser effect. Translational Relevance: By utilizing metabolic kinetics, we provide a 2D computational tool to predict oxygenation safety across the entire cornea with various types and designs of contact lenses.

Therapeutic HL-Contact Lens versus Standard Bandage Contact Lens for Corneal Edema: A Prospective, Multicenter, Randomized, Crossover Study

“…It is important to mention that the oxygen permeability ( Dk value) of the lens is as high as a therapeutic lens and there is no need for additional support of oxygen or other materials as suggested in other papers [ 17 ].…”

Central-to-peripheral corneal edema during wear of embedded-component contact lenses

“…Details of the corneo-scleral anatomy are provided in Kim et al [33]. SL and SCL with embedments are referred to as ESL and ESCL, respectively.…”

“…To provide direct comparison between mathematical and clinical analyses, Leung et al [15] utilized metabolic kinetics [31] and the hydration pump-leak mechanism of Maurice [32] to determine central corneal swelling associated with different hypoxic conditions caused by various types of soft-contact-lens (SCL) wear. Recently Kim et al [33] expanded this work to 2 dimensions (2D) to determine central-to-peripheral corneal swelling for SCL and scleral-lens (SL) wear. The metabolic-mathematical model revealed that limbal metabolic support significantly reduces mid-peripheral and peripheral corneal swelling.…”

“…The metabolic-mathematical model revealed that limbal metabolic support significantly reduces mid-peripheral and peripheral corneal swelling. Further, the metabolic model disclosed that corneal efflux of lactate into the limbus and influx of limbus bicarbonate ions into the cornea are the primary contributors to reducing corneal edema at the mid-peripheral and peripheral regions of the cornea [33]. Surprisingly, supply of oxygen from the limbus had a marginal effect on reducing corneal edema everywhere [33].…”

“…The previously developed metabolic model of Kim et al [33] is expanded here to assess the hypoxic safety of embedded-component contact lenses for various designs and parameters by quantifying central-to-peripheral corneal edema associated with lens wear. Embedded-component contact lenses can utilize various lens-encasement platforms.…”