A Study of the Role of Therapeutic Contact Lenses in Drug Delivery
Fung, Evonne Yuewai; Lee, Jennifer; Tong, Anita; Tran, Baotram; Yau, Yuk Yee (Amy)
Glaucoma is an optical condition caused by pressure build up in the eye and is the leading cause of blindness. Current methods to treat glaucoma include medicated eye drops and oral medication, which are both inefficient methods of administration. Most of the medication in eye drops does not reach the target tissue. In addition, when taken orally, much of the drug circulates in the bloodstream instead of reaching the eye. This is a potential problem since drugs used to treat glaucoma, such as timolol maleate, are also prescribed to elevate hypertension. To avoid possible side effects, researchers have developed a novel method of drug delivery that involves enclosing the drug in the contact lens to be worn directly over the eye. The drug-encapsulated contact lens can deliver the drug to the target tissue more effectively. This paper focuses on the drug delivery of the therapeutic contact lens in the treatment of glaucoma using a computer-simulated model created by FIDAP, a computational fluid dynamic software. The problem is modeled as mass transfer of timolol maleate over four layers (lens, tear, cornea, and aqueous humor) of an axis-symmetric cylindrical slab. Results show that with an initial concentration of 7 mg/g contact lens in the contact lens, the minimum effective concentration of 1.8 ?g/mL is achieved in the aqueous humor layer after 45 minutes. The contact lens continues to deliver the drug into the eye at above this concentration for another 75 minutes before dropping below the minimum effective concentration at 1.5 hours. Sensitivity analysis shows that cornea diffusivity is the most important parameter in the solution.
contact lens, eye, drug delivery