Improvements in surgical techniques and IOL materials and designs have lowered PCO rates but have not eradicated the problem. Therefore, despite several complications and the cost burden, Nd:YAG laser capsulotomy is still the most frequently used treatment of PCO. Consequently, the development of an alternative medical treatment of PCO is of critical importance. Alternatives include selectively destroying residual LECs while avoiding toxic effects on other intraocular tissues. Intraocular application of pharmacological agents to prevent PCO has been investigated by several laboratories, and the commonly used methods for this application are direct injection into the anterior chamber, addition to the irrigating solution, or impregnation of the IOL. Pharmacological agents such as thermosetting plastic prepared with phenol formaldehyde resins (Catalin), methotrexate, mitomycin, daunomycin, and fluorouracil have been shown to be effective in preventing PCO in vitro,19,117,118but in vivo studies have shown their toxicity to corneal endothelial cells, iris, ciliary body epithelial cells, and retina.19Studies tested cytotoxic and therapeutic agents, including diclofenac sodium,119saporin,120thapsigargin,22salmosin,121minoxidil,122a matrix metalloproteinase inhibitor (Ilomostat),41and cyclo-oxygenase 2 inhibitors.123These studies showed promise for finding medical treatment of PCO by targeting the survival, adhesion, proliferation, migration, and transdifferentiation of residual LECs, but the risk of their toxic effects on surrounding intraocular tissues has restricted their clinical use. Malecaze et al124,125provided a gene therapy approach to target LECs in the capsular bag by inducing therapeutic apoptosis by overexpression of proapoptotic genes. Walker et al126showed the blocking effect of an Src family kinase inhibitor on PCO development in a chick model of the lens capsular bag.