October 2010

 

OPHTHALMOLOGY NEWS

 

Contraindicated procedures?


by Matt Young EyeWorld Contributing Editor

   

Retina photographs of wet macular degeneration and optical coherence tomography images of a pigment epithelial detachment Source: Kevin Gregory-Evans, M.D.

Although multifocal IOLs are a boon to patients desiring enhanced vision after cataract surgery, they may decrease visualization for surgeons during future surgical procedures on patients in whom these lenses are implanted. A new case study, published in the May issue of Clinical Ophthalmology, found that macular surgery was exceedingly difficult in a patient with a multifocal IOL. "Macular surgery can be performed in an eye with a diffractive multifocal IOL," wrote study co-author Makoto Inoue, M.D., Ph.D., Kyorin Eye Center, Kyorin University School of Medicine, Tokyo. "However, decreased contrast sensitivity and ghost images may interfere with the intraoperative view through the diffractive IOL in complicated cases."

Understanding the difficulty

Dr. Inoue analyzed a 70-year-old woman who was implanted with the Tecnis ZM900 (Abbott Medical Optics, Santa Ana, Calif.) aspheric diffractive multifocal IOL. Although the patient's vision was good post-op (20/25 left eye uncorrected visual acuity), she complained of decreasing vision in the left eye to 20/40 after 2.5 years. "Funduscopic examination showed an ERM [epiretinal membrane] in the left eye," Dr. Inoue reported. "Increased macular traction was believed to cause the visual deterioration."

A decision to attempt vitreous surgery was made. It was performed with 25-gauge instruments and a conventional contact lens system. "During the procedure, the surgeon noticed several unique findings through the diffractive multifocal IOL," Dr. Inoue reported. "To focus on the retinal vessels and macula, the surgeon needed to adjust the focus several times, especially when observing the premacular membrane, requiring great effort with decreased contrast sensitivity."

However, the ERM was peeled successfully. The reflections off the intravitreal instruments changed. "[They] appeared as multiple wave-shaped arches or as one reflection off the instrument depending on the distance from the retina," Dr. Inoue reported. When triamcinolone acetonide crystals were injected into the vitreous for visualization purposes, "multiple or double crystals were observed; and the crystals were elongated radially in the peripheral field of the flat contact lens, although the crystals in the central field were not duplicated." However, visualization of the peripheral retina and retinal vessels was similar to that of a conventional IOL. The patient's vision improved after surgery to 20/25 4 months post-op. ERM was completely removed.

The results in context

Although potential vitreoretinal complications in eyes with multifocal IOLs have been raised, Dr. Inoue suggested this study is only among a handful that have been published. "We previously reported a case of retinal detachment that required vitreous surgery after implantation with a diffractive multifocal IOL," Dr. Inoue reported. "In the patient, intravitreal TA [intravitreal triamcinolone] crystals disappeared at some depth in the vitreous cavity and then reappeared abruptly and were seen in duplicate. We were concerned about how diffractive multifocal IOLs affect visualization in macular surgery, which requires more precise visualization and delicate surgical procedures, including removal of ERMs."

This case demonstrated that macular surgery can be successful in patients with multifocal IOLs, Dr. Inoue reported. The study also found that decreased contrast sensitivity and ghost images resulting from the multifocal IOL in place can affect the intraoperative view substantially. "The diffractive multifocal IOL may interfere with surgical procedures in complicated cases," Dr. Inoue concluded. "Despite favorable near and far visual results with diffractive multifocal IOLs, a symptomatic decrease in contrast sensitivity resulting from the optical design and precise observation of the retina and vitreous are concerns."

John D. Sheppard, M.D., professor of ophthalmology, microbiology, and immunology, Eastern Virginia Medical School, Norfolk, Va., agreed that visualization in patients with multifocal lenses is difficult and worrisome. "Talk to the retina surgeons," he said. "They really dislike multifocal lenses."

These surgeons require exquisite visualization of the posterior pole when performing macular surgery and have difficulty focusing when diffractive lenses are in place. "It's a challenge in what is already a difficult case," Dr. Sheppard said. Silicone lenses also make things difficult for retinal surgeons, Dr. Sheppard said. "Silicone lenses produce condensation, and there's an incompatibility with silicone oil used in the eye," he said. "But silicone IOLs are the most cost-effective, and multifocal lenses are the vanguard of technological innovation for practice growth."

Dr. Sheppard said his clinic takes pains to screen potential multifocal candidates for possible problems later. "We are extremely careful to screen patients for incipient macular disease; these are the last people you want to give a multifocal lens to," he said.

Routine macular optical coherence tomography is becoming more common, and that may also help to prevent problem cases. "But ultimately we want to make the patient, not the retinal surgeon, happy," Dr. Sheppard said. Still, if patients show any potential for macular disease, they are better candidates for monofocal lenses, he said.

Editors' note: Dr. Inoue has no financial interests related to this study. Dr. Sheppard has no financial interests related to his comments.

Contact information

Inoue: +81-422-47-5511, inoue@eye-center.org
Sheppard: 757-622-2200, docshep@hotmail.com

Contraindicated procedures? Contraindicated procedures?
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