Peter Stalmans (Leuven, Belgium)

Purpose:

During surgery, several complications can occur: posterior lens capsule aspiration, aspiration of retinal tissue into the cutter during vitreous base shaving and pressure alterations leading to hypotony (inducing collaps and even subchoroidal haemmorrhage) or hypertony (compromising the retinal perfusion).

Methods:

Several soft and hardware features were developed for the Dual Associate device (DORC):
1. During phaco surgery, vacuum sensor monitors the amount of aspiration generated by the venturi system. Threshold vacuum setting is programmed allowing obtaining high vacuum during tip occlusion to ease the lens removal. In the presents of no tip occlusion reduced vacuum is automatically generated.
2. Persistalic pump system with a preset fluid flow and automated vacuum adaptation was designed for using the cutter in close proximity to the retina,
3. Feedback system between the aspiration rate (vitrectome) and the infusion rate (air-driven infusion line) was developed.

Effectiveness:

1. Using the threshold venturi setting during len’s segments removal; aspiration of the len’s pieces is facilitated due to the amount of vacuum available. This system allows avoiding aspiration of the posterior lens capsule as well.
2. The peristaltic pomp settings during vitrectomy result in a constant fluid flow, which is the key factor to avoid inadvertent retinal aspiration when the cutter is used close to the retina.
3. The feedback system between the vitrectome aspiration and infusion rate yields a highly stable intra-ocular pressure, regardless of the amount and speed of fluid aspiration from the eye. There is no need to change the intra-ocular pressure settings during the procedure.

Take Home Message:

The newly developed features provide an improved safety during vitrectomy:
1.Extremely stable anterior chamber during phaco surgery.
2.Inadvertend aspiration of the retina with the cutter is avoided
3.During vitrectomy, the intra-ocular pressure is kept constant, regardless of the amount of aspiration generated by the cutter.