Combined Hydrogel/Microparticle Eye Drops for Sustained Delivery of Glaucoma Medication Glaucoma is the second leading cause of blindness worldwide and costs $2.5B to treat every year in the US alone. Topical eye drops are the current clinical standard in treating glaucoma and numerous other ocular pathologies. However, the frequent and difficult administration of eye drops makes them highly inefficient, with patient compliance in some cases as low as 50%. Poor compliance puts patients at risk for worsening vision and blindness, with a significant increase in treatment costs. Both patients and clinicians would benefit greatly from a more efficient treatment method that would increase patient compliance and deliver drug more efficiently to the aqueous humor to avoid systemic toxicity. Contact lenses and novel eye drops including nanoparticles are a comfortable and familiar alternative to traditional eye drops, but have only extended delivery windows to several hours or days at most. In contrast, formulations that can provide weeks to months of drug release currently require injection or implantation into the eye by a clinician. If an ocular deliery strategy could combine the comfort and simplicity of an eye drop with long-term drug delivery, it could revolutionize the delivery of not only glaucoma medication, but other ocular medications as well. The goal of this project is to develop a new, easy-to-administer, and noninvasive treatment capable of long- term release of glaucoma medication to the eye. Such a formulation would dramatically reduce patient compliance-related complications due to the simple, patient-administered format and the marked decrease in dosing frequency. The consequences of systemic toxicity and insufficient ocular absorption inherent to eye drops would be mitigated with a more direct delivery of over 100x less drug. Using a combined approach of highly customizable, polymer microparticle (MP)-controlled delivery of brimonidine tartrate (BT) contained in an in situ forming gel eye drop will provide a comfortable and vastly more efficient delivery format for the treatment of glaucoma. The gel eye drop is intended for administration to the lower fornix, where it comfortably conforms to the conjunctival cul-de-sac and releases drug for up to 30 days. The project's primary objective is to optimize custom-designed MPs to release therapeutic levels of BT and engineer a thermoresponsive, hydrogel matrix for retaining the MPs. In silico modeling methods will be used to develop the drug delivery system, followed by requisite in vitro validation of drug release kinetics. The gel/MP system will be tested in a rabbit model of ocular hypertension to demonstrate clinically relevant results and sustained BT delivery. Finally, this new drug delivery system will be evaluated as a platform for treating othe ocular diseases by using noninvasive magnetic resonance imaging (MRI) to monitor drug release and distribution in vivo. Ultimately, this work represents the initiation of preclinical efficacy and safety testing of a modular strategy for delivering of a variety of ocular therapeutic using novel in vivo drug delivery and visualization techniques.

Public Health Relevance

Glaucoma is the second leading cause of blindness worldwide, with this prevalence expected to increase substantially in coming years as it is more common in elderly adults. The most common and preferred treatment to slow or stop the progression of glaucoma is the self-administration of topical eye drop medication as many as three times a day. Eye drops are a highly inefficient treatment method due to limited retention and absorption of drug, patient compliance issues due to the frequent dosing, and side effects resulting from high levels of drug needed to achieve therapeutic effects. Current efforts to develop new sustained release formulations that provide controlled delivery of glaucoma drugs for days or weeks (avoiding the need for topical drops) require invasive clinical procedures to insert or inject the drug delivery system and are associated with significant side effects themselves. This project will investigate the potential of treating glaucoma with a noninvasive, patient-administered eye drop that comfortably forms a gel in the area beneath the lower eyelid, where it will provide up to one month of glaucoma medication.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Bioengineering of Neuroscience, Vision and Low Vision Technologies Study Section (BNVT)
Program Officer
Liberman, Ellen S
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pittsburgh
Engineering (All Types)
Schools of Engineering
United States
Zip Code
Ratay, Michelle L; Bellotti, Elena; Gottardi, Riccardo et al. (2017) Modern Therapeutic Approaches for Noninfectious Ocular Diseases Involving Inflammation. Adv Healthc Mater 6:
Fedorchak, Morgan V; Conner, Ian P; Schuman, Joel S et al. (2017) Long Term Glaucoma Drug Delivery Using a Topically Retained Gel/Microsphere Eye Drop. Sci Rep 7:8639