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R. L. Avery, S. Saati, M. Journey, S. Caffey, R. Varma, Y. C. Tai, M. S. Humayun; A Novel Implantable, Refillable Pump for Intraocular Drug Delivery. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3799.
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To develop and test a miniaturized, implantable, refillable, remotely controlled drug pump, which can precisely deliver very small quantities of medicine to the aqueous or vitreous cavity.
A mini-drug pump consisting of a drug reservoir, electrolysis chamber, battery and electronics for controlling drug delivery was developed to inject fluid into the eye via a cannula. Microcurrents hydrolyze water in the electrolysis chamber and force fluid out the drug reservoir. The device can be remotely programmed and activated. The battery can be inductively charged, and the drug reservoir can be refilled by an in-office procedure. Prototypes of this pump were implanted in two dogs under the temporal conjunctivae with the cannula inserted into the anterior chamber. One device contained 0.5% timolol, and one contained 0.004% travoprost. The pump was remotely activated on different days. Control eyes received the same medications topically. IOP was measured hourly for 8 hours after administration. Animals were followed by slit lamp examination, photography and fluorescein angiography.
The electrolysis pump operated with a flow rate in the pL/min to µL/min range using driving current from 5 µA to 1.25 mA. No complications were noted in the dogs after 3 months of observation. The reduction of IOP was comparable in both groups (pump vs. control) as demonstrated in Figure 1.
Prototype ocular mini-drug pumps were built, implanted, and successfully activated remotely. These results provide "proof of principle" that it is possible to deliver drugs in a very controlled manner with this device. Potential applications include not only glaucoma, but also many retinal diseases currently treated with intravitreal injections. This platform needs further testing to determine the long-term effectiveness and biocompatibility of an electronically controlled implanted pump.
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