| Description |
We design and characterize a novel, single-use device to perform capsulorhexis, a critical step during cataract surgery, during which a 5-mm-diameter incision is made in the anterior lens capsule. This device, the Helicotome, is a hand-held tool based on a superelastic shape-memory-alloy blade to perform the circular incision in the lens capsule. The blade deploys into a helix shape within the eye through a cannula that is inserted into a small incision in the cornea. When pressed into the anterior lens capsule and retracted, the blade produces a nearly circular incision in the lens capsule. The cut diameter and circularity of the prototype Helicotome capsulorhexis excisions are compared against manual and laser excisions performed in published studies. The prototype Helicotome deviates from a target excision diameter of 5 mm by 0.17 mm +/- 0.34 mm (mean +/- standard deviation) for 17 bovine capsulorhexis procedures, compared to the manual lens capsule excisions that deviate from the specified diameter of 5 mm by 0.337 mm +/- 0.258 mm for 18 manual procedures, and the laser-excised lens capsules that deviate from a specified diameter of 4.6 mm by 0.029 mm +/- 0.026 mm for 39 laser procedures. The prototype Helicotome produces a mean circularity of 0.83 +/- 0.06, the manual method achieves a mean circularity of 0.80 +/- 0.15, and the laser capsulorhexis procedures achieve a mean circularity of 0.94 +/- 0.15. The average procedure duration for all experiments performed with the prototype Helicotome blade is nearly 75% shorter than the average procedure duration of 120 seconds using the currently available manual method. The prototype Helicotome yields a success rate of 30% in creating a full 360° capsulorhexis, and incomplete cuts can be completed manually. The results obtained with the Helicotome are comparable to those provided by currently available methods, but is easier to use and reduces the time required to perform the procedure. However, future prototypes of the Helicotome should be scaled down to be deployed within the anterior chamber of the eye without contacting the posterior of the cornea, and should be modified to improve repeatability. |
