Laser System Shows Promise for Cataract Surgery

To reach the degree of precision needed, the researchers use optical coherence tomography (OCT) to obtain a three-dimensional (3D) map of the eye. Using that image, proprietary software is used to pinpoint the ideal pattern for the laser to follow. It is then superimposed on a 3D picture of the patient's eye, so that the surgeon can confirm it is on track before starting the procedure, in addition to monitoring it as the cutting proceeds.

A clinical trial in 50 patients revealed no significant adverse events during the femtolaser capsulotomy. Using a measurement that ranks a perfect geometric circle as a 1.0, the researchers found that the laser-based technique scored about .95, compared with about .77 for the manual approach to cutting the disc from the capsule. They also found the edges of the cut were twice as strong in the remaining capsule, which subsequently serves as an envelope for the plastic replacement lens. The study describing the technique and the femtolaser device was published in the November 17, 2010, issue of Science Translational Medicine.

"The results were much better in a number of ways -- increasing safety, improving precision and reproducibility, and standardizing the procedure,” said lead author Daniel Palanker, Ph.D., an associate professor of ophthalmology. "Many medical residents are fearful of doing capsulorhexis, and it can be challenging to learn. This new approach could make this procedure less dependent on surgical skill and allow for greater consistency.”

The researchers reported that the laser-assisted surgery offered other benefits aside from the capsulotomy; since the laser has already spliced the lens, there is less need to use an ultrasound probe, which in hard cataracts can sometimes create too much heat and damage the corneal endothelium and other surrounding tissue. The laser also can also create a multi-planar zigzag pattern for the incision in the cornea, allowing the incision to self-seal and decreasing the likelihood of infection and other complications.

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Stanford University School of Medicine