Novel method to quantify traction in a vitrectomy procedure.
OBJECTIVE
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).


CONCLUSIONS
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.
Teixeira
Anderson
A
Eye Concepts Laboratory, Los Angeles, CA, USA.
Chong
Lawrence
L
Matsuoka
Naoki
N
Rowley
Adrian
A
Lue
Jaw-Chyng
JC
McCormick
Matthew
M
Kerns
Ralph
R
Humayun
Mark
M
D000818:Animals; D004867:Equipment Design; D012160:Retina / Q000502:physiology*; D013314:Stress, Mechanical; D013552:Swine; D014618:Vacuum; D014821:Vitrectomy / Q000295:instrumentation / Q000379:methods*