Poor visual acuity resulting from optic atrophy and chronic macular edema is a common outcome in vitrectomy, despite successful structural results. Uncontrolled intraocular pressure (IOP) and its rapid fluctuations during surgery may contribute to this problem. In this project we utilize recent advances in fiberoptic sensor technology and digital control logic to design, construct, and test in vitro an instrument that will measure and automatically control IOP during vitreous surgery. Pressure signals from a microminiature fiberoptic pressure transducer placed at the surgical site will be processed via digital feedback circuitry. Specially-designed algorithms will be used to automatically control fluid infusion into the surgical site so as to maintain constant IOP at levels controlled by the surgeon. two different types of fiberoptic pressure sensors will be tested for their suitability and will be compared to current strain-gauge transducer technology. Cost effectiveness of each type will be compared. The necessary software will be developed to operate a digital feedback system for controlling fluid infusion into the surgical site. Linear actuators will be evaluated for their effectiveness in fluid flow and pressure regulation. Comprehensive hazard analysis will be performed on every component, as well as the entire design, to make the instrument as failsafe as we can. The prototype will be tested in both porcine and eyebank eyes. Results of Phase I will guide the optimization of the clinical prototype, which will be constructed and tested during clinical trials in Phase II.
Successful development of the device would have rapid acceptance by a majority of vitreous and retina surgeons. If use of the instrument results in decreased incidence of macular edema, the device could become useful in cataract surgery. Furthermore, the device could benefit cataract surgery from the standpoint of astigmatism decrease during wound closure.
