Know your options when expanding a pupil

Reviewed by Brian Hunter, MD

Humans are creatures of habit, even ophthalmologists. Having learned to use one device for pupil expansion, it is easy to forget that there are alternative devices.

“I have seen too many residents having a hard time getting the most familiar device, the Malyugin Ring (MicroSurgical Technology), into the iris, just shredding the margins, and an even harder time getting it out again,” said Brian A. Hunter, MD, in private practice at Fishkind, Bakewall, Maltman, Hunter & Associates Eye Care and Surgery Center, Tucson, AZ, and clinical professor of ophthalmology at the University of Arizona.

“The Malyugin Ring is an effective device, but it has a steep learning curve,” Dr. Hunter added. “I looked around and found the I-Ring (Beaver Visitech International), which appeared to be a lot easier for residents to get into the eye and out again without causing excessive damage.”

Dr. Hunter outlined his experience with the I-Ring. He pointed out that optical outcomes with the new device are similar to those obtained with the Malyugin Ring, but relatively few resident training programs appear to offer an option.

Most programs introduce the Malyugin Ring as the first and only pupil expansion device, Dr. Hunter said. The familiar device is not necessarily better, just more familiar. Having mastered one steep learning curve, many ophthalmologists are wary of learning a new device.

The problem is most acute in patients with small pupils with intraoperative floppy iris syndrome (IFIS). These patients do not respond adequately to pharmacological mydriasis and need mechanical dilation.

Risks with no device

Not using some sort of device to achieve adequate intraoperative mydriasis carries a long list of risks: iris sphincter tears, hemorrhage, zonular dialysis, anterior or posterior capsular damage, increased OR time, and lens dislocation or drop. Postoperative risks include uveitis, irregular pupil, transillumination defects or iris atrophy, and corneal edema.

“We need pupil expansion devices to provide adequate exposure, to maximize safety and efficiency, maximize postop results and prevent complications,” Dr. Hunter said. “You don’t want to make the problem worse by causing damage with your device.”

Iris hooks are the simplest pupil expansion devices and are useful when the patient has asymmetric iris defects. However, hooks are difficult to position properly, increase OR time, and can cause pupil damage.

The Malyugin Ring is easy to insert and gives a good field of view, but the device has a steep learning curve with complex removal, especially for less-experienced surgeons. It also is prone to iris trans-illumination defects (TIDs), sphincter and anterior chamber tears, and requires special instrumentation. It also has the advantage of being the most familiar device on the market and the de-facto choice for experienced ophthalmologists.

The I-Ring is easy to insert and to remove and has a small field of view than the Malyugin Ring–6.3 mm compared to between 6.25 to 7.0 mm. The I-Ring also is subject to TIDs and the flexibility that makes it easy to insert and remove also makes it difficult use properly.

Small study

Small study

Transillumination defects caused by I-Ring use. Courtesy of Brian A. Hunter, MDDr. Hunter initially thought he was seeing more TIDs from the I-Ring than from the Malyugin Ring. The I-Ring has a slightly larger profile on the pupil, so it seems reasonable that it could cause more defects. None of the defects he noted were visually significant, but they were large enough to be visible during an exam, even if patients did not see any effect.

“I decided to do a small study with my own patients, looking to see just what kind of iris defects they had from the two devices,” Dr. Hunter said. “At least in my practice, results between the Malyugin Ring and the I-Ring were very similar, not as significant as I thought I was seeing.”

Dr. Hunter followed 14 patients, 7 with the I-Ring and 7 with the Malyugin Ring. Outcomes were inflammation, TIDs, and pupil shape 1-day postop and 14-days postop. Patient demographics were similar between the 2 groups, as were the pre-op pupil size and cataract grade.

Transillumination defects caused by Malyugin Ring. Courtesy of Brian A. Hunter, MDPostop results were similar. On day 1, the I-Ring had a mean of 1.5 cells versus 1.3 cells for the Malyugin Ring. Both rings had a single TID. The I-Ring had 2 pupil defects and the Malyugin has zero defects.

On day 14, the I-Ring had no cells vs. 0.1 cells for the Malyugin Ring. The I-Ring had 1 TID, the Malyugin Ring had 2. Neither ring showed any pupil defects.

“The I-Ring works well, though no one device is right for every surgeon or patient,” Dr. Hunter said. “I would encourage more people to use the I-Ring, especially those (physicians) who are in training. You get better outcomes without the steep Malyugin Ring learning curve. Especially when you are training residents, the I-Ring is a much better way of getting (residents) to do those harder cases earlier.”

Brian A. Hunter, MD

P: 520-293-6740

E: huntereyemd@gmail.com

This article was developed based on a presentation that Dr. Hunter delivered at the 2016 American Society for Cataract and Refractive Surgery annual meeting.