Swept-source OCT, auto-recognition enhance femtosecond laser platform

May 1, 2015

Updates to a femtosecond laser platform include a swept-source optical coherence tomography imaging system and new software that provides auto-recognition of landmarks in the eye.

 

Take-home message: Updates to a femtosecond laser platform include a swept-source optical coherence tomography imaging system and new software that provides auto-recognition of landmarks in the eye.

 

By Cheryl Guttman Krader; Reviewed by Jeffrey Whitman, MD

Dallas-Hardware and software upgrades to a femtosecond laser platform (Victus, Bausch + Lomb) expand the capabilities and increase efficiency of an already outstanding system, according to Jeffrey Whitman, MD.

An advanced swept-source optical coherence tomography (OCT) imaging system can be used to drive incision depth and detail the architecture of arcuate incisions. Coupled with new software, the imaging system also provides auto-recognition of key landmarks in the eye, plus capsule tilt compensation, to provide automatic capsulotomy centration and maximize lens fragmentation.

The updated software also includes expanded options for lens fragmentation patterns and corneal incisions.

“I always breathe a little sigh of relief and am more relaxed when I sit down to a cataract surgery case using [this laser], because I know it is going to be generally safer and easier,” said Dr. Whitman, president and chief surgeon, Key-Whitman Eye Center, Dallas.

“With the new updates, I can expect to provide excellent outcomes to patients and with increased efficiency,” he added.

Clarity of images

Providing real-time imaging, the femtosecond laser’s high-contrast, high-resolution imagery generated with the new swept-source technology is so remarkably clear and vivid that it is startling at first use, he said.

“You can clearly see the bubbles coming up as the capsulotomy is created and the detailed architecture of a three-step corneal incision is impressive,” he said.

The laser has always performed well for capsulotomy creation, achieving 95% free floating caps in his experience, Dr. Whitman noted. The new software now auto-recognizes the pupil and uses it as a landmark to center the capsulotomy.

“Surgeons can still do the centration manually if they choose,” he said. “Now, however, it comes up automatically for the surgeon’s review, which is a true timesaving feature.”

Expanded patterns

An expansion in options for lens fragmentation patterns is also part of the latest upgrades to the laser. Surgeons can now choose to create wedges, cylinders, or “French fries” by making radial cuts, rings, or combining the two.

“The new software gives surgeons much more flexibility in adjusting the fragmentation pattern based on the density of the lens,” Dr. Whitman said.

He explained how he prefers to divide softer cataracts using radial cuts, whereas for a denser nucleus he will create three to five central circles and then further divide the lens with four to six radial cuts.

“This pattern allows me to easily core out the center of the nucleus-which is always the most dense part of the lens-and then I separate the radial segments and remove those pieces of the pie,” Dr. Whitman said.

Using this approach for denser cataracts has cut down on “my total ultrasound power, making the procedure more efficient and safer than ever before,” he said.

Dr. Whitman reminds cataract surgeons that the laser was originally created for cornea treatments, and so it stands out in its performance for making corneal incisions.

The laser has a wet-to-dry patient interface, such that the vacuum ring is initially filled with fluid to create a liquid interface when the laser is being used for the capsulotomy and lens fragmentation, he noted. In preparation for the corneal incisions, the surgeon moves the cornea superiorly, which forces the fluid out of the interface.

“Having a liquid interface is helpful for the intraocular portions of the laser treatment,” Dr. Whitman said.

However, it is a drawback for making the corneal incisions, and no other laser gives surgeons the choice to go from wet to dry, he said.

“Some surgeons operating with other lasers have given up using them for creating the corneal-entry incisions because the incisions were so hard to open,” Dr. Whitman said.

With this laser, “I’d estimate that about 98% of the time, I can push right into the incisions, and I believe they close better than any incisions I create manually,” he said. “Right now I am working with the software to create a Wong supracorneal incision as well.”

The latest software update allows surgeons to now make three entry incisions instead of just two, and the incisions can be placed independent of each other anywhere on the cornea. Asymmetric incision can be made to correct irregular astigmatic patterns. Previously, the two incisions were yoked together.

Surgeons can choose to create one, two, or three-step corneal incisions.

Dr. Whitman said his preference for the main incision is the three-step architecture, and he places it right at the clear limbal area. With the real-time, swept-source OCT guidance, there is also no “guesstimating” about corneal thickness when deciding about limbal relaxing incision (LRIs) depth. Now, surgeons can adjust incision depth based on real-time pachymetry.

“Some surgeons feel that astigmatism correction with LRIs does not last,” Dr. Whitman said. “Based on what we learned from radial keratotomy, however, I believe that is only true if the incision is not made deep enough.

“Surgeons can now see the actual thickness of the cornea at the mid-point of the LRI and set the laser to cut the desired depth,” he said. “It’s very accurate and also very simple.”

Dr. Whitman said that he also likes the fact that LRIs are very easy to open with a dissector.

Using other femtosecond lasers, some surgeons will tout the fact that the LRI is stuck together because they say it allows titration of the astigmatic correction, he noted.

“However, with the easy-to-open incisions created using [this laser], I can get very predictable effects and outstanding results applying the manual LRI nomogram that I was satisfied with in the past,” Dr. Whitman said.

 

Jeffrey Whitman, MD

E: Jeffrey.whitman@keywhitman.com

Dr. Whitman is a consultant to Bausch + Lomb.