Effect of aging on heat transfer, fluid flow and drug transport in anterior human eye: A computational study

There are a lot of geometrical and morphological changes that happen in the human eye with age. Primary open-angle glaucoma, which is caused by the increase in intraocular pressure inside the anterior chamber of the eye is also associated with the physiological aging of the eye. Therefore, it is crucial to understand the effects of aging on drug delivery in the human eye when applied topically. Consequently, a numerical model of topical drug delivery for an aging human eye has been developed using commercial software COMSOL Multiphysics in the current study. Three different age groups (young, middle and old) have been considered and the changes in geometrical and tissue properties of different domains of the eye with age have been included in the numerical model. The effect of aging on heat transfer, aqueous humor flow, intraocular pressure and drug concentration in different domains and orientations of the eye have been investigated. Additionally, an attempt has been made to predict the best class of anti-glaucomatic treatment in silico that should be preferred to treat primary open-angle glaucoma effectively. Results illustrate that there is a decrease in the average corneal temperature and an increase in the temperature deviation across the cornea with age. Further, there is a decrease in the aqueous humor flow magnitude in the anterior chamber of the eye and an increase in intraocular pressure in the anterior chamber of older age groups, which leads to primary open-angle glaucoma. The reduced aqueous humor flow leads to increased drug concentration in the anterior chamber as well as iris and reduced drug concentration in the trabecular mesh of the older age groups, thereby affecting the treatment efficacy. Additionally, our simulated results demonstrate that anti-glaucomatic treatments should be more focused on treating the trabecular mesh rather than the ciliary body of the eye.