EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78788
August 2012 Treat the cause. Ophthalmic jet injector taxiing on the runway by Maxine Lipner Senior EyeWorld Contributing Writer Visit us at ESCRS 2012 Stand N214 for live treatments and product demonstrations The intravitreal injection New minimally invasive system promises heightened safety I LipiFlow® is indicated for treatment of Meibomian Gland Dysfunction and evaporative dry eye. In clinical trials, gland secretions more than doubled, on average, following a single LipiFlow® treatment.1 Visit tearscience.com for complete product and safety information. Scan for a schedule of TearScience activities or visit tearscience.com magine being able to rapidly give a patient an intravitreal or subconjunctival injection with- out fear of injury from the nee- dle. A new minimally invasive device being studied, dubbed a jet injector, promises to give practition- ers a leg up in this regard, according to Gholam A. Peyman, M.D., emeritus professor of ophthalmol- ogy, Tulane University, New Orleans; professor of basic medical science, University of Arizona, Phoenix; and professor of optical sciences, College of Optical Sciences, University of Arizona, Tucson, who helped to pio- neer this system with his collabora- tors Dr. Michel Cormier and Kamran Hosseini. Dr. Peyman reported on some promising groundwork with the device in the January/February issue of Ophthalmic Surgery, Lasers, and Imaging, which set parameters for optimal pressure needed for intravitreal and subconjunctival injections in rabbit eyes. Dr. Peyman was spurred to develop the device by the desire to simplify and increase the safety of both intravitreal and subconjuncti- val injections, which are repeatedly performed by ophthalmologists. 1 Lane SS, et al. A New System, the LipiFlow, for the treatment of Meibomian Gland Dysfunction (MGD), Cornea 1/4/12 LipiFlow is a registered trademark of TearScience, Inc. Copyright © 2012 TearScience, Inc. All rights reserved. Considering the inner workings At the heart of the device is a micro- needle that communicates with an internal formulation chamber. It also has a piercing depth-limiting flange. "This flange restricts the ocular penetration to a depth of less than 1 millimeter," Dr. Peyman said. "Also it defines simultaneously the location of the pars plana when its edge is placed at the limbus." From an intravitreal perspective, he pointed out that this makes it easier to determine exactly where to place the device for intravitreal injection. The device is capable of produc- ing a force of up to 1,000 psi. It is the amount of this force that deter- mines where the medication will go. "Depending upon the force applied we can define if the medication will be injected into the subconjunctival space or in the intravitreal cavity," Dr. Peyman said. When the device was tested on 28 rabbit eyes, investigators deter- mined that a pressure of 76-156 psi was needed to facilitate subconjunc- tival injection and 974 psi for intrav- itreal injection, given the parameter chosen for the needle. New parame- ters for human eyes, however, will have to be determined. One of the strengths of the jet injector is the fact that the micro- needle is anchored in the sclera, minimizing potential infection risk. Dr. Peyman pointed out that with standard jet injectors without a micro-needle, which are used for vaccine injections under the skin, there can be potential contamina- tion stemming from microbes on the skin surface aspirated along with the fluid injected. This is not the case with this new system. "Because the needle penetrates about 0.1 mm inside the tissue, it also prevents as- piration of superficially located con- taminated fluid from the surface of the conjunctiva," Dr. Peyman said. "Having the needle inside of the tissue, one avoids communication with the conjunctival surface."