Mini drug pump for ophthalmic use.
OBJECTIVE
To evaluate the feasibility of developing a novel mini drug pump for ophthalmic use.


METHODS
Using principles of microelectromechanical systems engineering, a mini drug pump was fabricated. The pumping mechanism is based on electrolysis, and the pump includes a drug refill port as well as a check valve to control drug delivery. Drug pumps were tested first on the benchtop and then after implantation in rabbits. For the latter, we implanted 4 elliptical (9.9 x 7.7 x 1.8 mm) non-electrically active pumps into 4 rabbits. The procedure is similar to implantation of a glaucoma seton. To determine the ability to refill and also the patency of the cannula, at intervals of 4 to 6 weeks after implantation, we accessed the drug reservoir with a transconjunctival needle and delivered approximately as low as 1 microL of trypan blue solution (0.06%) into the anterior chamber. Animals were followed up by slit-lamp examination, photography, and fluorescein angiography.


RESULTS
Benchtop testing showed 2.0 microL/min delivery when using 0.4 mW of power for electrolysis. One-way valves showed reliable opening pressures of 470 mm Hg. All implanted devices refilled at 4- to 6-week intervals for 4 to 6 months. No infection was seen. No devices extruded. No filtering bleb formed over the implant.


CONCLUSIONS
A prototype ocular mini drug pump was built, implanted, and refilled. Such a platform needs more testing to determine the long-term biocompatibility of an electrically controlled implanted pump. Testing with various pharmacologic agents is needed to determine its ultimate potential for ophthalmic use.
Saati
Saloomeh
S
Doheny Eye Institute, University of Southern California Keck School of Medicine, Los Angeles, California, USA.
Lo
Ronalee
R
Li
Po-Ying
PY
Meng
Ellis
E
Varma
Rohit
R
Humayun
Mark S
MS
D000818:Animals; D000867:Anterior Chamber / Q000601:surgery; D004396:Coloring Agents / Q000008:administration & dosage; D003315:Cornea / Q000473:pathology; D016503:Drug Delivery Systems / Q000295:instrumentation*; D004572:Electrolysis / Q000295:instrumentation; D004867:Equipment Design; D005240:Feasibility Studies; D005451:Fluorescein Angiography; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D013508:Ophthalmologic Surgical Procedures; D019736:Prostheses and Implants; D011817:Rabbits; D013552:Swine; D014343:Trypan Blue / Q000008:administration & dosage
D004396:Coloring Agents; D009883:Ophthalmic Solutions; D014343:Trypan Blue