Will Marking Go Digital?

Although the implantation rate of toric IOLs around the globe is growing, one surgeon out of three is still hesitant to implant this kind of lens in eyes with moderate astigmatism, due to the risk of poor results from misalignment.

According to Tim Schultz MD, this is more of a problem of workflow, and digital marking could be a key to avoiding it.

“One surgeon out of three may not opt for a toric IOL for an eye with a 2.5 D of cylinder. These surgeons are not using toric IOLs because with 10-degree misalignment, we have a 30% reduction of the IOL functionality,” he said. “So, would perfect marking make a perfect result? No, there is much more behind this. We must address the whole workflow, and many problems can come from every step.”

While Dr Schultz said digitalising the workflow can be helpful to avoid errors with manual data entry, it is something to manage with care.

“We can have big variations in our measurements,” he explained. “Using an online calculator can lead to some errors, even if the calculator comes from a reliable source.”

The next step is axis calculation.

“Even in the biggest calculators, a 5- to 10-degree deviation occurs in 20% of cases. It is huge,” Dr Schultz said.

Yet manual markers also come with a price.

“If you ask a surgeon what the best marker is, they will reply, ‘The marker I use is the best,’” Dr Schultz said. “However, there are different kinds of markers with different advantages and disadvantages, especially regarding accuracy, and they all have one problem in common: globe rotation.”

There are several types of digital marking methods already available to surgeons. “Digital drawing is a superb, underrated option, but it is time consuming,” he observed. “Intraoperative measurements are helpful in IOL alignment, but you must enter the patient’s full biometry. Digital overlay is the big top, with automated data in a closed system with good usability, but it also has a high cost. Finally, intraoperative marking has two systems—the camera and the laser—that can do very thin lines on the cornea. This is the game changer.”

According to Dr Schultz, the literature shows slightly better results from digital marking than manual.

“In the trials, very well-performed markings will end up with something around a 4- or 5-degree margin of error. With the laser marking, the margin error is 2 or 3 degrees on average,” Dr Schultz said. “Of all the errors that can come up in the workflow, globe rotation is surely one of the most important. Having some laser markings that can remain visible after surgery—helping to find the correct position during and after surgery—shows how digital marking has an exciting potential to improve surgery. We will see how computer vision and artificial intelligence can further help us.”

Dr Schultz presented at the 2023 ESCRS Congress in Vienna.

Tim Schultz MD, FEBO is Head of Glaucoma and Eye Research Institute at the University Eye Hospital of Bochum, Germany. tim.schultz@kk-bochum.de