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G. Mahadevan, K. Jones, P. Selvaganapathy, H. Sheardown; An Intravitreal Device for Drug Delivery to the Posterior Eye for the Treatment of Age Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5823.
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Although a number of therapeutic drugs are available for the treatment of age-related macular degeneration, an effective means of delivery to the posterior eye is yet to be developed. In this work, we evaluated the feasibility of a drug delivery device fabricated using photolithographic techniques to create a replica mold that could be repeatedly used to cast polydimethyl siloxane (PDMS)-based devices. The PDMS reservoirs were coupled to hollow glass needles that could penetrate the sclera and vitreous. We sought to determine whether the resultant microfluidic system was capable of delivering liquid drug solution to the posterior eye segment of enucleated bovine eyes in a controlled and targeted fashion.
Silicon wafers were spin coated with one hundred micron-thick SU8 photoresist and were subsequently exposed using UV-photolithography for pattern transfer to create the structure of a microfluidic network. PDMS prepolymer was cast into this master mold to create replicas of the microfluidic network consisting of 300-micron microchannels reliably and repeatedly without subsequent need for expensive clean-room facilities. Glass microneedles were fabricated from capillary tubes using a pipette puller with tip diameters ranging from 200 nm to 10 micrometers, as measured using scanning electron microscopy. The needles were subject to plasma oxidation to increase adhesion and embedded in the PDMS microfluidic network. The device was placed onto the sclera of an enucleated bovine eye and inserted through the vitreous for infusion of a dye into the posterior segment.Results and Discussion:Devices were successfully fabricated using the process described. The device demonstrated delivery of a suspension of liquid dye into the ocular model at the targeted posterior eye delivery site. Optimization parameters will be presented as it is anticipated that tuning the device will permit the delivery of novel posterior segment drugs over a prolonged period.
An intravitreal device has been designed and fabricated that offers a flexible PDMS-based microreservoir coupled to an array of hollow glass microneedles. In this work, a device capable of storage, transport and ejection of a liquid solution that was capable of targeting the posterior eye segment was demonstrated. Further benefits of the work presented include ease of device fabrication, low manufacturing costs and minimal use of expensive clean room facilities.
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