DOD-Funded Researcher Develops Novel Patch for Ocular Trauma
Featured speaker Mark Humayun, M.D., Ph.D. (University of Southern California)
On March 6, AEVRs Decade of Vision 2010-2020 Initiative hosted a Congressional briefing entitled Development of a Thermo-Responsive Patch for Ocular Trauma featuring Mark Humayun, M.D., Ph.D., Interim Ophthalmology Chair and Co-Director of the newly-created Eye Institute at the University of Southern California (USC). Dr. Humayuns research is funded by the Peer Reviewed Vision Trauma Research Program (VTRP) within the Department of Defense (DOD). He was funded in the FY2011-2012 cycle, in which the VTRP awarded 21 researchers a total of $13.8 million to study DOD-identified vision trauma research gaps. His research addresses a major gap—the lack of a means for battlefield medics to seal lacerations and perforations of the eye, thereby protecting the eye before the soldier is transported to a more robust medical facility where trained ocular surgeons can properly suture the globe.
Dr. Humayun is clinician-scientist who treats patients and conducts research into saving and restoring vision in both the civilian and defense arenas using his training as both an ophthalmologist and engineer. For example, his collaboration with Second Sight Medical Products, Inc., the Department of Energys National Laboratories and its Artificial Retina Program, and the NEI has resulted in the Food and Drug Administration (FDA)-approved Argus II Retinal Prosthesis System, which is enabling those who are otherwise blind to identify doors, crosswalks, and even utensils, facilitating activities of daily living. In addition to such biomechanical approaches, he is also studying stem cell approaches to save and restore vision.
He first emphasized that a soldier experiencing a sight-impairing or blinding eye injury may face upwards of 50-60 years of vision loss, since 97 percent of injuries occur in soldiers 20-24 years old. That is why his research is investigating ways to stabilize battlefield eye injuries—specifically corneal and scleral (eye wall) wounds—such as lacerations, perforations, and penetrating injuries, as well as intra-ocular foreign bodies (IOFBs). He emphasized that in the event of severe ocular lacerations, the combat medic does not have the skills or treatments to provide immediate care to prevent the vitreous gel from leaking out, dangerously low eye pressure, or infection from setting in before the soldier can be transported to a medical facility with the required microsurgical equipment and an ocular surgeon.
He described some of the options for treating these injuries, noting that it is critical to maintain the transparent nature of the cornea and reduce scarring. Gluing is impractical, since it is irreversible and may have toxicity issues. Simply patching the eye has the potential complication of placing too much pressure on the globe, forcing further leakage of ocular fluids from the lacerations. His approach is using nanotechnology to develop the worlds first reversible glue. In contrast to most glues, it does not become adhesive until it is warmed up and reaches body temperature-meaning that it can be safely and easily transported and applied to the eye, and only then does it become adhesive and form a seal. This material has a long shelf life and can be stored in extreme conditions, and only becomes sticky when applied to the body.
The material Dr. Humayuns team has developed also prevents scarring, because it is only sticky on one side-the other side being smooth-so that it does not adhere to surrounding tissue. He explained that the material, Poly-N-Isoproplacrylamide, or PNIPAM, is also not exothermic during the phase transformation, meaning that it does not give off heat as it becomes adhesive, again preventing damage to the eye. The early versions of PNIPAM did not have the desired strength to ensure a solid bond, but the current version has the strength needed to ensure that the patch will hold the tissue together while the soldier is transported.
What makes this ocular patch so ideal in providing a temporary wound closure for an injured globe is that, once implanted in an eye, it can remain there until the soldier is transported to a medical facility with an ocular surgeon, who can remove the patch by the simple application of sterile saline. The saline lowers the materials temperature sufficiently so that it loses its adhesive quality and is easily extracted, allowing the surgeon to then perform the necessary permanent repairs to the eye. In a video that was part of the presentation, the patch can be seen as repeatedly transitioning from sticky to non-sticky as saline is applied to an in-vitro eyeball. Because the patch is intended to be used for a very short term, the FDA regulatory approval process is also anticipated to be shorter, which should speed up the process for getting it into medical kits in the field.
In a discussion after his presentation, Dr. Humayun stressed that there are no limits on the size or shape of the wounds for which the patch can be used. He also explained that this work is his teams first step in the research and development of several other novel treatments. While development of a temporary patch is an important step in preventing ocular damage until a surgeon can repair the eye, we are looking to develop a limbic stem-cell treatment that would actually stimulate the eye to repair itself, rather than needing microsurgery to treat an ocular trauma.
The briefing was co-sponsored by AEVR members Blinded Veterans Association (BVA) and the Association for Research in Vision and Ophthalmology (ARVO).
Dr. Humayun with former DOD/VA Vision Center of Excellence Director Don Gagliano, M.D., who currently serves as an industry consultant
From left: Jim Vale (Vietnam Veterans of America), Chong Cornell and her husband, BVA President Mark Cornell, and Glenn Minney and Tom Zampieri, Ph.D. (BVA). Mr. Cornell testified earlier that day at a joint House/Senate Veterans Affairs Committee hearing, at which he stated BVAs support for VTRP funding of $10 million.
Earlier in the day, Dr. Humayun met with Chris Gaspar from the office of Senator Dianne Feinstein (D-CA). Previously, Chris had worked in the office of Congressman Jim Moran (D-VA), where he was the key staffer in getting the VTRP funded in the defense appropriations bill for the past 5 years.