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Young Hyun Kim, Meng C Lin, Clayton J Radke; Limbus Metabolic Supply Reduces Peripheral Corneal Edema with Contact-Lens Wear. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1178.
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Although the cornea is thicker near the periphery, limbal supply of oxygen is thought to reduce swelling in that region (Herse et al. 1993). Because of experimental limitations, however, measured peripheral corneal edema with contact-lens wear is imprecise (Herse et al. 1993; Holden et al. 1985; Wang et al. 2002; Martin et al. 2009). To address limbal influence on cornea edema, we extend the 1D metabolic-based study of Leung et al. (2011) to 2D for both scleral (SL) and soft (SCL) contact lenses.
A 2D model of the cornea and sclera was designed on Comsol Multiphysics 5.4 platform (Comsol Inc., Burlington MA). Metabolite concentrations are quantified by incorporating the metabolic kinetics of Chhabra et al. (2009) and Leung et al. (2011). Metabolite and oxygen supply from the limbus, and the oxygen supply from air are incorporated. Corneal swelling is determined by the change in stromal hydration caused by the change in metabolite concentrations during hypoxia according to the pump-leak mechanism of Maurice (1972). Post-lens tear thickness (PoLTT) profiles from the center to the periphery are determined based on SCLs and SLs geometries and the central PoLTTs.
The solid lines in Figure 1 represent the 2D-predicted swelling profiles for SL and SCL for different oxygen permeabilities. Maximum swelling occurs at the midperiphery and zero swelling at the corneal periphery. For comparison, the dashed line in Figure 1 represents predicted swelling with no limbus interaction. Clearly, the limbus dramatically reduces swelling near the corneal periphery. The reason for the dramatic reduction is the supply of bicarbonate and oxygen from the limbus to the cornea and the removal of corneal lactate through the limbus to the sclera.
We establish the major role of the limbus in corneal edema upon contact-lens wear. By utilizing the pump-leak mechanism and metabolite-kinetic chemistries, corneal swelling profiles from the center to the periphery are quantified. The developed model reveals the importance of limbal supply of metabolites on corneal edema and suggests lower oxygen demand at the periphery than at the center.
This is a 2020 ARVO Annual Meeting abstract.
Figure 1: Corneal swelling profiles with SL and SCL wear from the center (x = 0) to the periphery (x = 5.6 mm). Solid and dashed lines represent the swelling profile with and without metabolic support from the limbus, respectively.
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