Spotlight ON TECHNOLOGY & TECHNIQUE

Doctors Influenced Femto Safety Focus

OptiMedica looked to ophthalmologists for advice on Catalys.

By Bill Kekevian, Associate Editor

Among the doctors OptiMedica drafted to help develop the work flow features of its Catalys femtosecond laser was Jonathan Talamo, MD, of Talamo Hatch Laser Eye Consultants in Boston. Dr. Talamo, also an associate professor at Harvard Medical School, is an early adopter of new technologies and has been involved in 20 years worth of clinical trials, many of which led to FDA approvals for laser vision correction technologies. So when he, along with fellow researchers, told OptiMedica in 2008 of an opportunity to redesign its femtosecond prototype for cataract surgery, the company listened.

Liquid Optics Interface

The device performed well in the prototype phase, but showed some problems from a clinician’s perspective. “Unlike many medical device companies, OptiMedica views doctors as collaborators,” Dr. Talamo says. “One of the great things about this Silicon Valley team is their willingness to go back to the drawing board and innovate until they get it right.” (OptiMedica is based in Sunnyvale, Calif.) Among other things, he adds, “We helped them understand some design flaws that were seriously compromising the potential of laser cataract surgery systems”.

Dr. Talamo says he and other researchers noticed that during the docking process, the single-piece interface prototype applanated the cornea and exerted too much pressure on the eye, causing patient discomfort and high IOP spikes. It also led to corneal folds, degrading the ability of the system to image intraocular structures and scattering laser light into the eye. That contributed to incomplete anterior capsulotomies.

In those days, this was not an unusual problem for any of the femtosecond cataract systems, but it was one without a great solution. “That led to the hunt for what became liquid optics,” Dr. Talamo says. Liquid optics, acting as the patient interface system, uses liquid immersion to overcome the problem of corneal applanation with the docking mechanism. This way, nothing presses on or distorts the cornea during imaging and laser treatment. Instead, it provides a clear optical path for real-time video and OCT imaging.

Wide-field View

The liquid optics interface also helps create a wide-field view. “With some other laser systems you can’t see the whole cornea every time, and as a result you can’t always make incisions, whereas with the Catalys system there is always plenty of room to treat the lens and make precise peripheral and arcuate corneal incisions” Dr. Talamo says. “Also, if you’re not compressing the cornea, you get a better image. Because the image is so precise and the media are so clear, it is possible to perform anterior capsulotomy, lens fragmentation and lens softening with much less energy than some other systems use.”

Lower energy results in less iris irritation and less cavitation bubble formation, reducing the risk of miosis and distention of the capsular bag from the laser treatment, according to Dr. Talamo. The two-piece docking process is also gentle on patients, minimizing scleral contact. Patients are more comfortable and not subjected to high IOP spikes during treatment, as a recent Ruhr University Eye Clinic study demonstrated. 1 This, Dr. Talamo says, is particularly important for cataract patients, who are likely to be elderly and may have ocular comorbities such as glaucoma and retinal microvascular disease.

Superior Safety

Another feature unique to the Catalys is its integral guidance imaging. “With the Catalys, the imaging process is all automated and the treatment is image-guided,” Dr. Talamo says. First, an integrated OCT system visualizes the ocular surfaces. It requires minimal manual adjustment, Dr. Talamo says, as the device directs the laser pulses precisely to the intended locations the surgical team pre-programs.

The surgeon then reviews the OCT images to verify the software has interpreted them properly and makes adjustments if needed. Integral guidance automatically detects the corneal, iris and lens surfaces and creates safety or “red” zones. The safety zones are a default that keeps the laser from treating too close to the wrong landmarks, while at the same time accounting for lens tilt that might result in an asymmetric treatment. After the surgeon confirms the customized treatment plan, the laser delivers to the intended location and maintains those safety zones.

“The Catalys user interface is a powerful visual aid and is very simple to navigate, which makes performing surgery a low-stress experience” Dr. Talamo says. “You can have a one-touch, customized approach prepared for the patient ahead of time, which minimizes time under dock and improves work flow in the operating room.”

Other safety features include an integrated bed with custom headrest and a lateral force sensor. “The bed provides a stable environment which optimizes and maintains head position during imaging and laser treatment, unlike an everyday, rollaway stretcher,” Dr. Talamo says.

The Catalys vs. The Black Cataract

The Catalys can take a difficult case and reduce it to a routine procedure, according to Dr. Talamo. One of his patients presented for cataract surgery after multiple corneal graft rejections and placement of a tube shunt with scleral patch graft for steroid-induced glaucoma. The brunescent lens was grade 5+ on the LOCS scale — literally a “black” cataract.

“The endothelial cell count was low from repeated rejection episodes and prolonged periods of elevated IOP, and both the glaucoma specialist and I were concerned that the graft would promptly fail if traditional phacoemulsification were used to remove the lens, leading to yet another procedure,” Dr. Talamo says.

The Catalys enabled Dr. Talamo’s team to not only place the dock over the irregularity the shunt created, but also to image and treat the eye through the corneal irregularities of the graft-host interface and a highly dense cataract, resulting in the need for minimal ultrasound and intraocular manipulations during phacoemulsification. The next day, the graft remained clear and the patient’s vision was correctable to 20/30.

The Catalys is currently FDA approved for single-plane and multiplane arc cuts and incisions in the cornea, capsulotomies and lens fragmentation. OM

Reference

1. Schultz T, Conrad-Hengerer I, et al. Intraocular pressure variation during femtosecond laser-assisted cataract surgery using a fluid-filled interface. 2013;39:22-27.