EyeWorld Asia-Pacific June 2016 Issue

June 2016 22 EWAP FEATURE Scanning electronmicroscopy shows that the Zepto capsulotomy edge has a uniquemorphology characterized by an extremely smooth functional edge (arrow). Detailed analysis revealed that Zepto not only creates a perfectly round, tag-free opening in the capsule, but at the same time places a microscopic eversion at the edge to present a small amount of the capsule underside for maximal edge integrity during surgery. An example of a Zepto capsulotomy in a human cadaver eye New technology for capsulotomy by Ellen Stodola EyeWorld Contributing Writer A new disposable, handheld device could automate creation of a perfect, circular capsulotomy A t the 2015 American Academy of Ophthalmology (AAO) meeting in Las Vegas, David F. Chang, MD , clinical professor, University of California, San Francisco, and in practice in Los Altos, Calif., discussed the Zepto capsulotomy instrument (Mynosys, Fremont, Calif.), a new disposable technology aimed at automating production of a stronger and perfectly sized anterior capsulotomy. Creating a perfectly round anterior capsulotomy of a precise diameter is one advantage offered by the femtosecond laser. “However, this technology entails significant costs that are usually borne by the patient, if and when such billing is allowed,” Dr. Chang said. “The size of the laser and the need for imaging and docking create logistical workflow issues and limit its utility for eyes with small pupils.” Several published studies have raised additional questions about whether the femtosecond laser capsulotomy is more likely to tear compared to a manual continuous curvilinear capsulorhexis (CCC). Mynosys has developed the Zepto Precision Pulse Capsulotomy (PPC) device, which is a disposable, handheld instrument that would be used in the normal surgical sequence instead of a cystotome and capsule forceps. The instrument tip consists of a circular nitinol ring with an edge that is precision engineered on a micron scale. The ring is elongated and compressed for insertion through a small clear corneal incision. Because nitinol is a super elastic shape memory alloy, the ring immediately reassumes its native circular shape once it enters the OVD-filled anterior chamber. The initial model developed will produce a 5-mm diameter capsulotomy. The cutting ring is surrounded by a thin, clear silicone shell that is used to apply gentle suction to the anterior capsule against which it is apposed. This suction brings the ring edge into uniform contact with the anterior capsule. A train of tiny brief electrical pulses causes water molecules trapped between the ring edge and the microscopically stretched anterior capsule to vaporize. This phase transition creates an instantaneous mechanical splitting of the anterior capsule along the entire ring circumference, resulting in a perfectly circular opening of a precise diameter. There is no cautery or burning of tissue, and all 360 degrees of the capsulotomy are created at the exact same instant. A small console placed on top of or integrated into the phaco machine creates the suction and generates the precision electrical pulses. The device was developed through testing in rabbit and human cadaver eyes, and results