A paper from Stanford University School of Medicine, published in Science Translational Medicine, presents clinical findings about a new system for femtosecond laser-assisted cataract surgery that safely cuts 12 times more precisely than the traditional method, and leaves edges twice as strong in the remaining lens capsule. The paper focuses on a system by OpticaMedica Corp. (Santa Clara, CA), which funded the study—although technology to perform laser capsulotomy is being developed by a number of companies, including Technolas (Munich, Germany) and LensAR (Winter Park, FL).
Currently, cataract surgery involves capsulorhexis (manually controlled removal of a disc from the capsule surrounding the eye's lens), after which the lens is broken up by ultrasound and suctioned out. The new approach, capsulotomy, allows a laser to pass through the outer tissue (without the eye being opened), cut a hole in the capsule, and slice up the cataract and lens—all before the patient enters the operating suite. The laser also creates a multi-planar incision through the cornea that stops just below the outermost surface, which means that the surgeon needs to cut less once the operation begins.
Lasers used in cataract surgery have exacting specifications: the abilities to cut tissue deep inside the eye, ionize tissue at a selected focal point, and use pulse energy at a power level low enough to avoid collateral damage. The team found the proper balance through a series of experiments. To guide the laser and evaluate its performance, they used optical coherence tomography (OCT) to create a three-dimensional map of the eye, which enabled development of software that generates the ideal pattern for the laser to follow. The pattern is superimposed on a three-dimensional picture of the patient's eye before and during the procedure.
A clinical trial revealed no significant adverse events and showed the laser-based system came much closer to adhering to the intended size of the capsular disc (within 25 μm vs. 305 μm in the manual procedure), and came closer to cutting a perfect circle, too. So when a plastic intraocular lens is placed, it will be better centered and fit tighter. The approach offers other benefits, too, including less need to use the ultrasound probe, and the ability to cut in a multi-planar zigzag pattern, which promotes healing.
The U.S. Food and Drug Administration (FDA) is now evaluating the machine.
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