Abstract
Purpose :
A silicone frontalis sling is often used in cases of blepharoptosis repair where there is little to no levator function. The slings generally have a great success rate, however, in some circumstances, the silicone can break, resulting in sling failure. Breakage can occur intra-operatively or at any time post-operatively. No studies to date have compared the effects of different instrumentation on the strength of the silicone tubing. This study is the first to compare the effect of surgical manipulation on the tensile breaking force of the silicone sling tubing. The primary aim was to compare the force in Newtons required to break the tubing.
Methods :
This prospective comparative study measured silicone frontalis sling tensile strength after three different types of surgical manipulation: 1) hand-tied with no instrument manipulation; 2) surgical tie with smooth forceps; 3) surgical tie with 0.5-toothed forceps. For each of these three conditions, 14 trials were performed to determine the average tensile strength (in Newtons) of each group.
Results :
Analysis of Variance (ANOVA) testing was used to determine statistical significance between the three groups, with a p-value of 4.655 x10-7. Post-Hoc testing was then used to compare individual groups. Results of this study indicated no statistically significant difference between the hand-tied silicone sling group and the smooth forceps-tied group (means 5.08N vs 5.10N, p-value 0.89). However, there was a statistically significant difference between the hand-tied group and the toothed forceps group (means 5.08N vs 3.64N, p-value 0.001) and between the smooth forceps and the toothed forceps group (means 5.10N vs 3.64N, p-value 0.001).
Conclusions :
Manipulation with toothed forceps leads to a statistically significant decrease in the overall tensile strength of the silicone sling compared to non-toothed forceps or hand tying. This may be due to disruption of material integrity by the instrument teeth, leading to a lower force required to break the sling (See Figure 1). As wear and tear of silicone slings may lead to disintegrative damage over time, the least amount of baseline manipulation prior to implantation should be performed. Therefore, use of toothed forceps should be avoided, as baseline breaking force decreases and may lead to earlier sling failure.
This is a 2020 ARVO Annual Meeting abstract.