A Polymeric Device for Sustained Drug Release With Intraocular Lens Implantation for Cataract Surgery

Abstract

Purpose: : To develop a simple polymeric drug release device for the prevention of post-operative infection after cataract surgery in the developing world.Cataract is the leading cause of treatable blindness worldwide and the population afflicted by cataract is increasing globally. Post-operative infection is a major concern in the developing countries, resulting from suboptimal sterile operating conditions and scarce availability of post-operative medication. We aim to develop a novel drug delivery system that allows sufficient sustained antibiotic level during the post-operative recovery period for cataract surgery.

Methods: : Polyhydroxyethyl-methacrylate (pHEMA) hydrogel was used as a drug depot. The sustained release characteristics were achieved with subsequent surface modification of the hydroxyl groups reacted with octadecyl isocyanate, forming mono-layer covering. Norfloxacin was used as a testing antibiotic. The surface modification was optimized to allow sustained release over a period of two weeks. The device was first tested in vitro for antibiotic release patterns using spectrophotometry. The antibiotic function of the device was then further tested in vitro using a silicone biofilm model.Further in vivo feasibility was investigated using a rabbit model. The control group of rabbits underwent standard cataract surgery with IOL implant and post-operative topical antibiotic and steroid. The experimental group received the polymeric device inserted with standard 3-piece IOL the time of surgery and received only topical steroids post-operatively. In vivo antibiotics level was sampled from the anterior chamber for up to 30 days. Clinical outcomes of both groups were also evaluated.

Results: : Our in vitro data demonstrate that the pattern of antibiotic release can be achieved by optimization of the surface coating. Our in vivo results demonstrated sustained sufficient antibiotic concentration (above MIC for most common bacteria related to endophthalmitis) for more than 4 weeks. There was minimum toxicity observed in vivo. Both groups of animals recovered from surgery without evidence of infection.

Conclusions: : The initial findings of the polymeric drug delivery device demonstrate the feasibility delivering sufficient antibiotic in the anterior chamber for the immediate post-operative period in a rabbit model. The device is simple to produce and may help alleviate the potential post-surgical infections due to the lack of medications in the developing nations.

Keywords: antibiotics/antifungals/antiparasitics • intraocular lens • drug toxicity/drug effects