Novel method to quantify traction in a vitrectomy procedure.

Aim: To report a novel method to quantify traction applied to the retina using vitreous cutters during pars plana vitrectomy.

Methods: Fresh porcine eyes were positioned in a specially developed holder and transfixed to the retinal layers with a wire and the other end fixed to the load cell of a strain gauge. Five separate 20-gauge electrical drive mechanism vitrectors were introduced into the eye at a 45 degrees angle and positioned at a distance of either 3 or 5 mm from the retina. Data from the strain gauge were acquired and the traction force computed.

Results: The analysis revealed that the vitreoretinal traction increased by 7.90 dynes for each 100 mm Hg increase in vacuum (p<0.05). The traction forces decreased by 2.51 dynes for each 500 cuts per minute increased (p<0.05) and the traction force increased by 2.17 dynes at 3 mm compared with 5 mm (p<0.05).

Conclusion: The traction was directly proportional to the aspiration vacuum and inversely proportional to the cut rate. The cutter traction force increased with proximity to the retina.