A force-sensing microsurgical instrument that detects forces below human tactile sensation.
OBJECTIVE
To test the sensitivity and reproducibility of a 25-gauge force-sensing micropick during microsurgical maneuvers that are below tactile sensation.


METHODS
Forces were measured during membrane peeling in a "raw egg" and the chick chorioallantoic membrane models (N = 12) of epiretinal membranes. Forces were also measured during posterior hyaloid detachment and creation of retinal tears during vitrectomy in live rabbits (n = 6).


RESULTS
With the raw egg model, 0.5 ± 0.4 mN of force was detected during membrane peeling. In the chorioallantoic membrane model, delaminating the upper membrane produced 2.8 ± 0.2 mN of force. While intentionally rupturing the lower membrane to simulate a retinal tear, 7.3 ± 0.5 mN (range, 5.1-9.2 mN; P < 0.001) of force was generated while peeling the upper membrane. During vitrectomy, the minimum force that detached the posterior hyaloid was 6.7 ± 1.1 mN, which was similar to the force of 6.4 ± 1.4 mN that caused a retinal tear. The rate of force generation, as indicated by the first derivative of force generation, was 3.4 ± 1.2 mN/second during posterior hyaloid detachment, compared with 7.7 ± 2.4 mN/second during the creation of a retinal tear (P = 0.04).


CONCLUSIONS
Force-sensing microsurgical instruments can detect forces below tactile sensation, and importantly, they can distinguish the forces generated during normal maneuvers from those that cause a surgical complication.
Wilmer Eye Institute, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
Sarah
S
Sunshine
Marcin
M
Balicki
Xingchi
X
He
Kevin
K
Olds
Jin U
JU
Kang
Peter
P
Gehlbach
Russell
R
Taylor
Iulian
I
Iordachita
James T
JT
Handa
D000818:Animals; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000601:surgery; D004195:Disease Models, Animal; D019773:Epiretinal Membrane / Q000601:surgery; D004867:Equipment Design; D008866:Microsurgery / Q000295:instrumentation*; D013508:Ophthalmologic Surgical Procedures / Q000295:instrumentation*; D011312:Pressure; D011817:Rabbits; D015203:Reproducibility of Results; D012167:Retinal Perforations; D012371:Robotics / Q000295:instrumentation*; D012677:Sensation; D012680:Sensitivity and Specificity; D014821:Vitrectomy; D020255:Vitreous Detachment / Q000601:surgery