Just imagine trying to cut a perfect circle, roughly one-third the size of a penny, with a sharp knife by hand. Now consider that, instead of paper, the material you are working on is a thin, transparent layer of tissue that easily tears. Finally, try to imagine doing all of this on a person's eyeball – and even the slightest mistake could result in a serious impairment to their vision.
This is all standard practice in cataract surgery – a procedure known as capsulorhexis – which involves the removal of a disc from the capsule surrounding the eye's lens. An extremely delicate operation, this is one of the few aspects of cataract treatment that has not yet been enhanced by technology. But this could all be about to change.
Recent developments in guided laser systems could soon eliminate the need for such manual dexterity. In a paper published by the Science Translational Medicine journal last month, researchers from Stanford University revealed some promising trial results.
The scientists presented clinical findings about how a new system for laser-assisted cataract surgery is not only safe, but also cuts circles with 12 times more precision than those produced by traditional methods. In addition, edges in the remaining capsule, which serves as a pocket for the plastic replacement lens, are left twice as strong as with conventional techniques.
"The results were much better in a number of ways — increasing safety, improving precision and reproducibility and standardising the procedure," said Daniel Palanker, the university's associate professor of ophthalmology and lead author of the paper.
He added: "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."
Cataract surgery is one of the most commonly-performed procedures around the world, with more than 1.5 million operations carried out each year in the US alone. The treatment is required when a 'cloud' forms in the eye's lens, causing blurred, double vision and increased sensitivity to light.
While capsulorhexis is being performed, which involves making a circular incision in the eye, "the size, shape and position of the anterior capsular opening ... is controlled by a freehand pulling and tearing the capsular tissue," the researchers explained. After this, the lens is broken up with the use of an ultrasound probe, before being suctioned out.
This procedure then culminates with the intricate placement of an artificial lens in the empty pocket created in the capsule. Before closing the patient's eye, the surgeon will often make additional incision in the cornea, in a bid to prevent or lessen astigmatism.
With the new laser-assisted technology, a beam can pass through the outer tissue without the eye even being open. A hole is cut in the capsule and the cataract sliced up prior to the patient entering the operating theatre. Because of all this mechanised precision, once the surgeon gets to work, the removal of the cataract can be done comparatively quickly and easily.
"This will undoubtedly affect millions of people, as cataracts are so common," said Dr Palanker, though he expects it to take time for the new procedure to be adopted. At the moment, the procedure as a whole takes slightly longer than traditional methods and would cost significantly more.
However, he added: "There will be people who elect to have it done the new way if they can afford it. There are competitors coming out with related systems. This is what's exciting. This technology is going to be picked up."
by Martin Burns