SPOTLIGHT ON TECHNOLOGY & TECHNIQUE

Topography function just the start of what Cassini reinvents

The corneal analyzer is designed to provide multiple preoperative measurements.

By Bill Kekevian, Senior Associate Editor

Managing cataract patients with astigmatism brings a host of challenges for surgeons. Issues of poor axis measurements or inaccurate images can lead to unsatisfactory results.

Measuring the axis of astigmatism is just one of the variables doctors need to correct. Try as they might, doctors couldn’t always obtain accurate measurements, due to technological limitations. To head-off those issues, imaging equipment must be precise. That necessity for better precision brought to market the Cassini corneal shape analyzer (i-Optics, Westborough, Mass.).

POINT-TO-POINT

The Cassini is a topographer with a different approach, one Mark Packer, MD, likens to the way satellite imaging from space works. Think of it as Google Earth for eyes. “The really unique aspect of this technology is that it uses an LED array,” says Dr. Packer, who practices in Bowie, Md.

The array of more than 600 yellow, red and green LED points triangulates ocular structures and puts the findings through an algorithm to calculate elevation. “By having that array and unique configuration at every point, you get a much more precise map of the corneal surface. It’s not simply calculating relative elevation, which can miss significant deformation,” Dr. Packer says.

The algorithm can then identify smeared or doubled points, which could indicate corneal irregularities, such as dry eye. “As a topographer alone it has a lot of advantages,” he says. “It’s the latest and the greatest.”

TRUEVISION COMPATIBILITY

However, the Cassini offers additional capabilities, according to Dr. Packer. Beyond its topographical application, it can be integrated into the full TrueVision Refractive Cataract Toolset surgical guidance suite. TrueVision is a 3D imaging system for microsurgery with which the Cassini was designed specifically to integrate.

The topography map is aligned with a 3D image of the eye that the TrueVision software automatically registers to the actual eye intraoperatively. “What really makes the difference is when the Cassini is linked to the TrueVision system. That changes the workflow because the whole alignment of the toric lens is done in one sitting. It all just goes straight to the big screen in our operating room,” Dr. Packer says, referring to the Cassini’s exportable data and map feature.

“Now the image of the topographic map is aligned with the eye in the operating room. You can see the axis of astigmatism on screen. There’s no more ink marking. We’ve eliminated a major source of error,” he says.

UPGRADES ON THE HORIZON

Although not yet an available feature, i-Optics is working out a way to engineer the Cassini’s software to distinguish posterior reflections, according to Dr. Packer.

Providing that data, he says, will better avoid toric IOL overcorrection seen in cases of with-the-rule astigmatism or undercorrection in the case of against-the-rule astigmatism. OM