Ultrasound biomicroscopy (UBM) characteristics of scleral tunnels created with suture needles commonly used during strabismus surgery.

Purpose: To enhance the safety and efficacy of surgical treatment of strabismus, we sought to measure and determine the ultrasound biomicroscopy (UBM) profile of scleral tunnels created with needles commonly used during strabismus surgery, to determine which needles are less likely to create the complication of scleral perforation.

Methods: Adult cadaver eyes were secured in a styrofoam head. Intraocular pressure was maintained between 15 and 21 mm Hg. Then S14, S24, S28 and TG100 needles were used to create scleral tunnels simulating those created during routine strabismus surgery. Ten scleral tunnels were created with each needle type at 3 different sites on the globe, for a total of 120 passes. The thickness of the sclera and the maximum depth and length of each scleral tunnel were measured using UBM.

Results: The mean tunnel depth below the scleral surface (+/- SD) was 0.43 +/-0.11 mm, 0.37 +/-0.09, 0.40 +/-0.08 and 0.34 +/-0.07 mm, for the S14, S24, S28 and TG100 needles, respectively (P=0.002, One way ANOVA). For both the S14 and S28 needles, there was a "statistically significant" P 0.05) linear trend of an increase in the depth of the pass as the length of the pass increased (P=0.01 for the S14 and P=0.02 for the S28 {Pearson Correlation 2 tailed test}). A similar trend was found with the S24 needle but the trend was not "statistically significant" (P=0.35). No such trend was found with the TG100 needle.

Conclusions: Needle design had a definite impact on the characteristics of scleral tunnels created to simulate those made during strabismus surgery and may influence needle selection by the surgeon for different or various surgical circumstances, but the differences were not such as to predicate for or against the general use of any of these four needles for strabismus surgery.