Argon laser iridoplasty may improve vision in decentered multifocal IOL cases

Corrected distance visual acuity, subjective quality of vision were enhanced in most patients in a study.

Issue: May 10, 2012

For patients who experience a loss in quality of vision following multifocal IOL implantation due to decentration relative to the pupil, argon laser iridoplasty is an appealing alternative to lens exchange, according to a small study.

Perspective from Thomas John, MD,

“At 1 month, patients were happy because the quality of their vision had improved, both objectively and subjectively,” Allon Barsam, FRCOphth, one of the study authors, said in an interview with Ocular Surgery News.

The impetus for the study was the referral of many patients with multifocal IOLs who may not have been screened appropriately for the lens.

“These patients were not optimally happy following implantation because of decentration of their IOL relative to the pupil,” Dr. Barsam, who was a fellow in cornea, cataract and refractive surgery at Ophthalmic Consultants of Long Island, said.

Allon Barsam

Improving satisfaction in a patient with a multifocal IOL entails “navigating the Seven C’s,” Dr. Barsam said, referring to corneal astigmatism, corneal cylinder, capsule, cystoid macular edema, lens centration, pupil circumference and consecutive (both eyes implanted with a lens).

“We try to address all these issues in the rare patients who are not happy after multifocal IOLs,” he said. If all problems other than centration are addressed, then the only option is an IOL exchange.

Because a lens exchange is a relatively advanced procedure, Dr. Barsam and colleagues wanted to develop a procedure that is safer and less invasive.

“[The argon laser] induces heat when it is in contact with the tissues,” he said. “The heat, in essence, causes the iris to shrink and contract in the area in which the laser is applied. The laser also moves the pupil toward the area where the laser is being applied. Hence, the center of the pupil is altered by moving the pupil permanently.”

In other words, the pupil, as opposed to the lens, is repositioned.

Study results

The study, which was published in the Journal of Refractive Surgery, consisted of 14 eyes of 11 patients with at least 0.3 mm of decentration of the pupil center relative to the center of the IOL. Uncomplicated cataract surgery had been performed on all eyes at least 3 months before the iridoplasty.

The surgical technique entailed one treatment session in which four argon laser spots with a 500 µm diameter of 500 ms duration and 500 mW of power were applied to the iris mid-periphery.

“Outcomes were better than we expected,” Dr. Barsam, appointed consultant ophthalmic surgeon at Luton & Dunstable University Hospital, said. “Patients are definitely seeing better.”

Mean corrected distance visual acuity improved significantly from 20/35 to 20/25 at 1 month. Mean subjective quality of vision improved significantly from 2.9 to 7.7 on a scale of 1 to 10.

Dr. Barsam said surgeons need to modify the energy of the laser in line with the color of the iris for enhanced outcomes.

“For example, a dark brown iris, which will absorb argon laser energy significantly, does not need as much energy as a light blue iris. If surgeons use high energy on a light blue iris, they need to be careful about causing charring or an iris defect,” he said.

None of the study patients incurred any postoperative adverse events, including loss of lines of corrected distance visual acuity or worse symptoms after the laser procedure.

“In the majority of cases, the laser should solve the problem of decentration with a multifocal IOL,” Dr. Barsam said. “But if patients are visually asymptomatic, laser treatment should not be considered.”

Although Dr. Barsam is not involved in a follow-up study, he advocated a large, randomized controlled trial to fully evaluate the effect of laser treatment. – by Bob Kronemyer

Reference:

Barsam A, Voldman A, Holladay J, et al. Argon laser iridoplasty to improve visual function following multifocal intraocular lens implantation [published online ahead of print Feb. 15, 2012]. J Refract Surg. doi:10.3928/1081597X-20120209-01.

For more information:

Allon Barsam, FRCOphth, can be reached at Luton & Dunstable University Hospital NHS Foundation Trust, Lewsey Road, Luton, LU4 0DZ, UK; 44-845-127-0-127; email: abarsam@hotmail.com.
Disclosure: Dr. Barsam has no relevant financial disclosures.

Perspective

Thomas John, MD,

Quality of vision is of paramount importance in all our patients in clinical practice, but this is even more significant in the subset of patients that elects for premium IOLs. The amount of light rays entering the eye is largely regulated by the differing pupillary size in varying lighting conditions. When the final resting position of a multifocal IOL is off target, the pupil appears eccentric to the IOL center and the iris partially obstructs the IOL rings, resulting in degradation of the visual quality and an unhappy patient. Correcting this problem would normally include recentration of the IOL by surgical intervention, which adds potential visual risks both intraoperatively and postoperatively. The authors in this article have come up with a novel idea of moving the pupil instead of moving the IOL. Creating a laser induced shift of the pupil to the IOL center appears to largely correct this problem.

This technique of argon laser iridoplasty to cause pupillary shift to the desired position has a useful clinical application and may be considered as a first line option in all cases of multifocal IOL decentration, in an attempt to resolve most of the adverse ocular symptoms and once again have a happy patient.

Thomas John, MD,

OSN Cornea/External Disease Board Member

Disclosures: Dr. John has no relevant financial disclosures.