Grant: Collaborative Health Research Projects

MEDICAL PROBLEM: Glaucoma, a degenerative disease of the optic nerve, is the leading cause ofirreversible blindness in the world. In Canada alone, over 11,000 glaucoma operations are performed each year.A major limitation of current glaucoma surgery is the inablility to precisely adjust the amount of intraocularpressure (IOP) post-operatively. IOP must be lowered as precisely as possible because an IOP that is loweredexcessively can lead to blinding complications. Traditional 'trabeculectomy' surgery involves the creation of ascleral flap (a guarding trap door of tissue) and a small opening (fistula) to permit fluid egress from the eye'srigid corneo-scleral layers. This fluid is then captured under the mucus membrane layer of the eye called theconjunctiva, and reabsorbed by the body. The scleral flap is secured with standard sutures; however, preciselygauging the suture tension to attain the desired pressure lowering is difficult. Hence, in an attempt to avoidoverly low IOP, most glaucoma surgeons suture the scleral flap tightly and perform 'laser suture lysis' asneeded to break the sutures and allow the scleral flap to loosen. Unfortunately, completely severing sutures inthis manner is frequently associated with a precipitous drop in IOP and hence this approach fails to adequatelyaddress the need for precisely-controlled IOP lowering.OBJECTIVES: In response to the need for precise incremental IOP lowering, we have designed a new""laser-adjustable"" device for implantation during glaucoma surgery. The new device integrates a miniaturemechanical structure capable of redistributing the mechanical tension of the suture when the device interactswith laser light. This leads to a conformational change, which decreases the tightness of the suture withoutcompletely severing it. This allows for incremental and controlled IOP lowering. The laser required to alter thedevice is a safe and has been used for decades in eye care and is widely available in all ophthalmologydepartments. Our proposed project builds upon our initial work and will involve prototype optimization andtesting.