title: Suprachoroidal drug delivery to the back of the eye using hollow microneedles.
abstract: OBJECTIVE
  In this work, we tested the hypothesis that microneedles provide a minimally invasive method to inject particles into the suprachoroidal space for drug delivery to the back of the eye.
  
  
  METHODS
  A single, hollow microneedle was inserted into the sclera, and infused nanoparticle and microparticle suspensions into the suprachoroidal space. Experiments were performed on whole rabbit, pig, and human eyes ex vivo. Particle delivery was imaged using brightfield and fluorescence microscopy as well as microcomputed tomography.
  
  
  RESULTS
  Microneedles were shown to deliver sulforhodamine B as well as nanoparticle and microparticle suspensions into the suprachoroidal space of rabbit, pig, and human eyes. Volumes up to 35 μL were administered consistently. Optimization of the delivery device parameters showed that microneedle length, pressure, and particle size played an important role in determining successful delivery into the suprachoroidal space. Needle lengths of 800-1,000 μm and applied pressures of 250-300 kPa provided most reliable delivery.
  
  
  CONCLUSIONS
  Microneedles were shown for the first time to deliver nanoparticle and microparticle suspensions into the suprachoroidal space of rabbit, pig and human eyes. This shows that microneedles may provide a minimally invasive method for controlled drug delivery to the back of the eye.
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332-0100, USA.
authors.forename: Samirkumar R
authors.initials: SR
authors.lastname: Patel
authors.forename: Angela S P
authors.initials: AS
authors.lastname: Lin
authors.forename: Henry F
authors.initials: HF
authors.lastname: Edelhauser
authors.forename: Mark R
authors.initials: MR
authors.lastname: Prausnitz
mesh_terms: D000818:Animals; D002829:Choroid / Q000187:drug effects / Q000378:metabolism*; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry; D016503:Drug Delivery Systems / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D056965:Injections, Intraocular; D007429:Intraocular Pressure / Q000502:physiology; D008845:Microinjections / Q000295:instrumentation / Q000379:methods*; D008856:Microscopy, Fluorescence; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry; D009339:Needles; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000737:chemistry; D011817:Rabbits; D012160:Retina / Q000187:drug effects / Q000378:metabolism; D012590:Sclera / Q000187:drug effects / Q000378:metabolism; D013552:Swine
chemical_list: D004337:Drug Carriers; D004364:Pharmaceutical Preparations