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Aspheric IOLs appear to offer better vision to some glaucoma patients
Moderate to advanced cases benefit the most as contrast sensitivity and biocompatibility improve, surgeon says.
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CHICAGO — When implanting IOLs in moderate to advanced glaucoma patients, aspheric IOLs appear to offer better visual results than multifocal lenses, thus reducing additional visual loss, a physician said here.
“Best quality of vision is paramount in the visually compromised patient,” Richard L. Lindstrom, MD, said at Glaucoma Day 2008, held before the American Society of Cataract and Refractive Surgery meeting. “Presbyopia, particularly corrected with multifocal IOLs of the current generation, fairly compromises contrast sensitivity.”
Dr. Lindstrom, Chief Medical Editor of Ocular Surgery News, said careful attention to lens selection is important when performing lens exchange in glaucoma patients. Aspheric lenses appear to provide the best results for glaucoma patients with visual loss. Multifocal lenses seem to work best in glaucoma patients who have mild visual loss that is not expected to progress.
“I tend to think asphericity trumps multifocality for moderate or advanced glaucoma,” he said. “To me, in an ocular hypertension glaucoma suspect with no visual loss, multifocal modality is reasonable.”
Biocompatibility is also important when selecting lenses for glaucoma patients because of the potential for lost or enhanced vision after lens exchange, Dr. Lindstrom said.
Effective lenses
Studies have shown that spherical aberrations reduce contrast sensitivity. Aspheric lenses have better results in reducing aberrations than non-aspheric lenses, according to Dr. Lindstrom.
“There are good arguments for not using multifocal lenses. I’ve used multifocal lenses for years, but I don’t favor them in the patient who has significant glaucoma because of contrast sensitivity issues,” he said.
Glaucoma patients have reduced contrast sensitivity caused by the loss of ganglion cells from the disease. Neuronal- influenced contrast sensitivity loss does not respond well to manipulation.
Choosing the right IOL for glaucoma patients could provide a chance to potentially increase contrast sensitivity, enhancing patients’ postoperative vision, he said. He and colleagues use aspheric IOLs when implanting lenses in most typical open-angle glaucoma cases.
Some glaucoma cases, however, require a different approach. He cited extremely rare cases such as aphakic or hyperopic glaucoma that might benefit from LASIK or other treatments. Such cases should be assessed on an individual basis for best results, he said.
The next generation crystalens HD IOL (Bausch & Lomb), which Dr. Lindstrom helped to develop, may be an effective alternative in select cases, as there is no loss of contrast sensitivity with this IOL. The lens optimizes the optic shape, which enhances near vision and reduces spherical aberration, he said.
In addition to Bausch & Lomb’s lens, Alcon and Advanced Medical Optics also have aspheric IOLs available in the United States. New technology IOL status has been granted to those lenses by the Centers for Medicare and Medicaid Services, Dr. Lindstrom said.
“The next generation of accommodating IOLs may be a reasonable compromise for some glaucoma patients who really want to reduce their dependence on glasses,” he said.
Biocompatibility
More research is needed to determine the effect of IOLs on vision quality in glaucoma patients of varying disease severity, Dr. Lindstrom said. Special emphasis should be given to enhancing visual quality for those patients by maximizing optics and biocompatibility.
Available literature on biocompatibility in lens exchange appears to suggest two ideas about uveal or capsular biocompatibility, he said. The first idea is that the silicone used in current lenses has similar uveal biocompatibility than acrylic material when used in eyes that have an increased risk for preoperative inflammation.
The second idea is that capsular biocompatibility appears similar in silicone and acrylic materials and seems most dependent on the optic edge and haptic design, Dr. Lindstrom said.
In a study published in the Journal of Cataract and Refractive Surgery, Thomas W. Samuelson, MD, and colleagues examined those ideas by looking at giant-cell deposits on foldable IOLs after combined cataract and glaucoma surgery.
According to the study, Dr. Samuelson and colleagues chose to look at IOLs in conjunction with combined procedures because of the stress that the procedures place on the lens, showing the biocompatibility of each IOL.
Dr. Samuelson and colleagues found that inflammatory giant-cell deposit formation was significantly greater on first-generation silicone plate IOLs than acrylic or second-generation silicone IOLs. The formations were more common on acrylic than second-generation silicone lenses; however, that difference was not clinical or statistically different.
“The bottom line is they didn’t find any good reason to favor a hydrophobic or hydrophilic acrylic vs. a second generation silicone,” Dr. Lindstrom said. “There really isn’t a strong argument against current generation silicone in regards to uveal or capsular biocompatibility.”
For more information:
- Richard L. Lindstrom, MD, is the Chief Medical Editor of Ocular Surgery News. He is in private practice at Minnesota Eye Consultants, 9801 DuPont Ave. S., Suite 200, Bloomington, MN 55431; 612-813-3600; fax: 612-813-3660; e-mail: rllindstrom@mneye.com. Dr. Lindstrom is a consultant to Bausch & Lomb, Advanced Medical Optics and Alcon. He has a financial interest in the crystalens HD IOL.
- Bausch & Lomb, maker of the Crystalens HD IOL, can be reached at 26970 Aliso Viejo Parkway, Suite 100, Aliso Viejo, CA 92656; 866-393-6642; Web site: crystalens.com; email: contact@crystalens.com.
Reference:
- Samuelson TW, Chu YR, Kreiger RA. Evaluation of giant-cell deposits on foldable intraocular lenses after combined cataract and glaucoma surgery. J Cataract Refract Surg. 2000;26:817-823.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.