Beware Burn Risk With Dual-Mode Laser Systems

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Despite warnings, injuries with dual-mode laser capsulotomy/selec­tive laser trabeculoplasty (SLT) laser systems continue to occur. A team of retina subspecialists recently presented a case of a 65-year-old woman whose left macula was scarred when capsulo­tomy was attempted using the system’s SLT mode.¹

This is not the first publication to warn of the potential for serious injury when dual-mode capsulotomy/SLT sys­tems are operated in the wrong mode.² However, published reports of misuse have been scarce. Moreover, gag rules imposed in malpractice settlements prohibit publication of cases, including two other current cases known to the authors.¹

INJURY. (1) Baseline fundus photograph shows foveal retinal pigment epithelium (RPE) mottling from multiple laser lesions. (2) Three months later, traumatic RPE hyperplasia is more prominent, while surrounding hemorrhages have resolved.

Lack of awareness. “Many clinicians are unaware of and often surprised to learn of this serious recurrent injury,” said coauthor Martin A. Mainster, PhD, MD, at the University of Kansas School of Medicine in Kansas City. “The SLT mode of a capsulotomy-SLT laser sys­tem can cause devastating, permanent foveal damage when it’s used errone­ously in an attempted capsulotomy.”

Current case report. Dr. Mainster and his colleagues described the case of a woman who underwent cataract sur­gery—and then, a year later, required capsulotomy for each eye. Although the treatment of her right eye was successful, the capsulotomy of her left eye failed, and she reported severe vision loss in that eye one week later.

She was referred to the authors, and imaging revealed permanent macular and extramacular photothermal and photomechanical damage. The best-corrected visual acuity (BCVA) in her left eye declined from 20/30 to 20/400. Within three months, the BCVA in that eye was count fingers at 4 feet, and she was informed of her poor visual prog­nosis. The diagnosis: laser maculopathy. “SLT mode laser pulses passing through a patient’s pupil reach and destroy retinal tissue,” Dr. Mainster said.

How these accidents occur. These incidents occur when the laser system is inadvertently turned on in its SLT mode or left on after an SLT procedure for others to use, Dr. Mainster said. He explained, “A clinician performing a capsulotomy might confuse the SLT mode’s single-spot capsular reflection with the in-focus fusion of the capsu­lotomy mode’s multiple-spot–aiming interface.”

How to prevent further incidents. To prevent similar iatrogenic injuries, the authors recommend taking the following steps:

• Have clinicians—not technicians—select the laser delivery mode.
• Double-check the laser mode before treating.
• Enhance engineering controls, such as different-colored backgrounds for each laser mode on a touch screen.
• Require entry of a personal iden­tification number by clinicians—not technicians—to acknowledge a warning before the SLT mode can be used.
• Affix a conspicuous note to every machine warning users never to attempt capsulotomy when the device is in SLT mode. 

Ounce of prevention. Administra­tive and engineering controls could have prevented the woman’s injury, but such controls were either absent or ignored, the authors wrote.

With regard to treatment, Dr. Mainster said that treatments such as anti-inflammatory and neuroprotective drugs are usually ineffective for severe macular injuries. As he noted, “The best way to treat a laser injury is to prevent it.”

—Miriam Karmel

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1 Ledesma-Gil G et al. Ophthalmology. Published online May 17, 2020.

2 Liyanage SE et al. Br J Ophthalmol. 2014;98(1):141-142.

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Relevant financial disclosures—Dr. Mainster: Ocular Instruments: C.

For full disclosures and the disclosure key, see below.

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