Femtophaco surgery fosters improved outcomes

Jan 01, 2014

Femtophaco surgical procedures using a femtosecond laser have resulted in much-improved cataract and corneal outcomes.

Take-Home

Femtophaco surgical procedures using a femtosecond laser have resulted in much-improved cataract and corneal outcomes.

Dr. Chu

By Lynda Charters; Reviewed by Y. Ralph Chu, MD

Minneapolis-Advances in femtophaco surgical procedures have resulted in much-improved cataract and corneal outcomes.

The introduction of the femtosecond laser is the technology that enables these outcomes. In contrast to traditional cataract surgery, the femtosecond laser can create consistent, centered capsulorhexes of a desired size and limbal-relaxing incisions, the execution of which is controlled by computer.

This capability has impacted the enhancement rates dramatically, according to Y. Ralph Chu, MD, adjunct associate professor of ophthalmology, University of Minnesota, Minneapolis, and founder and medical director of Chu Vision Institute and Chu Surgery Center, Bloomington, MN.

“Anecdotally, this has decreased our enhancement rate in presbyopia-correcting IOL cases by 50%, from 13% to 6%,” he said.

Dr. Chu uses a femtosecond laser platform (Victus, Bausch + Lomb) that allows surgeons to perform both cataract procedures and make corneal flaps.

He talked about the specific laser capabilities that are facilitating these improved surgical outcomes.

Patient positioning, docking

Initially, the patient is brought into the laser room on a surgical gurney and the patient transfers him or herself to the laser bed.

“The bed is essential for obtaining the most accurate laser treatments, because even slight movements of the patient as a result of an unstable bed can cause discrepancies in the treatment,” Dr. Chu said. “Small movements may account for fewer free-floating capsulotomies.”

With a laser such as this particular platform-designed for LASIK flaps and for cataract procedures-the bed is an essential component especially when trying to achieve highly accurate treatments while, for example, aligning spots to cut a 180-µm LASIK flap, Dr. Chu explained.

The rate of free-floating capsulotomies in his institute is 99.9%.

Dr. Chu always positions a speculum between the lids for optimal docking. Though the speculum is unnecessary, the femtosecond laser cone has a large number of sensors that sense movement and prevent torsion and corneal folds, he noted.

“Anything that I can do to minimize the torsional forces helps me achieve greater surgical efficiency, more consistent docking, and generally a more-efficient procedure,” Dr. Chu said.

Docking involves placing a suction ring on the eye that is separate from the patient interface. A separate surgical microscope is positioned off to the side to visualize the eye for docking.

The femtosecond laser platform has both a liquid and a solid interface. During a cataract procedure, fluid is placed inside the suction ring well to create a liquid interface.

“During intraocular work, the laser is docked within the fluid meniscus,” Dr. Chu said. “This facilitates soft docking that minimizes corneal folds.”

During corneal procedures, the pressure between the patient interface and the cornea is increased, which removes the fluid and creates a hard dock. This increases the laser accuracy during these procedures by using the patient interface as a reference.

The suction when using the femtosecond laser is gentler compared with traditional LASIK suction devices and therefore, it is more comfortable for the patient, safer, and causes less subconjunctival hemorrhages than other suction rings.

The suction ring is locked into place when the laser cone is engaged within the suction ring. At this point there is no air in the fluid meniscus, and the sensors indicate that the z and x/y pressures are accurate.

“These sensors are very helpful in ensuring that the cone is perpendicular to the ocular surface for accurate laser delivery,” Dr. Chu said. “This gives us very consistent and excellent results for cataract and corneal procedures.”

The treatment, capsulotomy or limbal-relaxing incisions-which is preprogrammed by technicians-is delivered and completed in about 2 to 3 minutes.

Phaco factors

The key element during surgery is the strength of the capsulorhexis produced by the femtosecond laser. Dr. Chu typically performs a supercapsular cataract surgery with a tilt-and-tumble technique in which the nucleus is floated out of the capsular bag using balanced salt solution.

A concern when converting from a manual procedure to femtosecond laser is that this maneuvering might undermine the integrity of the edge of the capsulorhexis. Though recent research has shown that the edge of the capsulorhexis created by femtosecond laser is slightly more jagged on scanning electron microscopy images, this has not been evident in his experience with this laser platform.

“I have not had to change my technique to accommodate the femtosecond laser,” he said.

Another concern is that irritation/aspiration (I/A) can be more difficult during procedures when femtosecond laser is used to create capsulorhexis because the cortex may be fused to the capsule or the cortex seems stickier.

Dr. Chu said, however, that the cortex is cut cleanly, with no strands of cortex floating in the bag that are easy to grab. Surgeons must go further into the fornix of the capsular bag to grab the cortex.

He noted he routinely performs bimanual I/A, because it is easier to address hidden cortex and sweep the fornixes capture cortex, and facilitates better polishing of the anterior subcapsular rim especially when implanting premium IOLs.

The femtosecond laser seems to have made a refractive difference in his practice. He and his colleagues use a particular lens (Crystalens, Bausch + Lomb) as their presbyopic-correcting IOL of choice.

“When we compared patients who received femto with the patients who did not, we saw a substantial decrease in the number of patients with a Crystalens that required an enhancement,” Dr. Chu said. “This is the true testament to the performance of this laser platform.”

 

 

Y. Ralph Chu, MD

E: yrchu@chuvision.com

Dr. Chu did not indicate any proprietary interest in the subject matter.

 

 

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