Make laser capsulotomies larger to avoid tears, speaker says
KOLOA, Hawaii – In order to avoid tearing the capsule, make the capsulotomies bigger, a presenter said here.
“Laser capsulotomies can be perfectly placed, exact in terms of their centration, precise in terms of their circularity,” Mark Packer, MD, of Oregon Health & Science University,said during the “Cataract/IOL: Advances in Techniques and Technology to Improve Patient Outcomes” session at the Hawaiian Eye meeting. “They are much more circular than I can make even in the best circumstances – with big pupils, stable chamber, perfect view, viscoelastics.”
However, the literature has shown consistently that laser capsulotomies tear significantly more than manual capsulotomies, Packer said.
Most surgeons are making their laser capsulotomies at 4.7 mm and 4.9 mm diameter in order to get 360° overlap, he said. And when the capsulotomy is smaller, it can be prone to tears because any force being applied is distributed over a smaller area. A larger capsulotomy will distribute that force over a larger area; and will, therefore, be stronger.
According to Packer, the ideal diameter for a capsulotomy is at 5.25 mm.
“I think that’s where we should make our laser capsulotomies,” he said. “Not at 4.7 mm and 4.9 mm where these studies are showing we’re getting more tears, but farther out, at about five and a quarter.”
Or course, at that diameter, it may be difficult to find a good center for the capsulotomy, he said.
“If you think about it, must surgeons are using the pupil center as the center of their laser capsulotomy, and you know the pupil is decentered inferonasally. And so if you use the pupil center and you put it at five and a quarter, the edge of the capsulotomy runs off the edge of the lens optic, usually inferonasal,” Packer said.
“But there’s a way to avoid that, which is don’t center it on the pupil center, center it on the optical axis, which is closer to the center of the lens capsule,” he said. “Or you can center it on the lens apex, which these machines can find because they’re measuring the surface curvature of the lens in their imaging system. That way, you can center [the capsulotomy] in the center of the lens, not the center of the pupil.” –by Daniel Morgan
Disclosure: Packer is a consultant for Abbott Medical Optics and LensAR Inc.