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he emphasized that it's important to find the angle kappa and make cer- tain that you place the lens in the visual axis rather than in the center of the pupil. Amar Agarwal, F.R.C.S., presi- dent, International Society of Refrac- tive Surgery, American Academy of Ophthalmology, and director, Dr. Agarwal's Group of Eye Hospitals, Chennai, India, finds that angle kappa can be one of the biggest problems for centering multifocal IOLs. "You might have a lens that is well centered on the pupil, and you think the patient should be good, but some of these patients are un- happy," Dr. Agarwal said. "What we [find] in these patients is that they have an angle kappa." What normally happens is that a ray of light goes through the cen- ter of the pupil. However the person is not seeing through a pupillary axis; he sees a ray of light that goes through the fovea, which is the vi- sual axis. "If the pupillary axis and the visual axis are close by or nearly the same, there is no problem," Dr. Agarwal said. "That means if the ray of light is going through the visual axis it will also pass through the center of the pupil." In these ideal cases the patient will see mainly through the central optical zone of the multifocal IOL as is desirable. However, if the patient has significant angle kappa, the pupil- lary axis is not in alignment with the visual axis, which leads to pa- tient dissatisfaction even when the lens appears to be well centered. The problem, Dr. Agarwal finds, is that in such cases instead of passing through the central optical zone of the multifocal IOL, the ray of light is off-axis and may hit, for example, the first ring of the lens, bringing with it complaints of glare and over- all dissatisfaction. When it comes to taking such angle kappa into account, Dr. Agarwal pointed out that devices such as the IOLMaster (Carl Zeiss Meditec), LENSTAR (Haag-Strait, Mason, Ohio), Pentacam (Oculus, Lynnwood, Wash.), and Orbscan (Bausch + Lomb, Rochester, N.Y.) can help. For example, he pointed out that the IOLMaster will tell prac- titioners where the center of the rings is. He tends to use the Orbscan to show angle kappa but feels that any of these instruments can be helpful in this regard—the main thing is to recognize the importance of the angle kappa information. He will not implant a multifocal IOL in a patient who has a high degree of angle kappa. "I will not go beyond plus 5 degrees of angle kappa," he said. Meanwhile, Dr. Donnenfeld favors the iTrace (Tracey Technolo- gies, Houston) and the OPD-Scan III (Nidek, Fremont, Calif.), which he feels offer valuable information about angle kappa as well as the center of the visual axis. "I think those are some good instruments that are just coming into use," Dr. Donnenfeld said. He also finds the TrueVision system helpful for identi- fying the position of the non-dilated pupil. In cases where the patient has significant decentration despite the practitioner's best efforts, Dr. Donnenfeld has developed a technique to remedy the situation, which can be done a couple of weeks post-op. "I will mechanically bring the iris back into place and do an argon laser iridoplasty," he said. "The argon laser pulls the iris over the center of the pupil so that you can fix angle kappa by moving the iris so that it is coincident with the patient's visual axis." Going forward, Dr. Donnenfeld thinks that the next pioneering realm in refractive IOL surgery will be determining effective lens place- ment to improve refractive out- comes and reduce post-op refractive error. "I think this will be the next area of interest—how we can put the lens in a better place to optimize the patient's refractive result." EW Editors' note: Dr. Agarwal has no financial interests related to this article. Dr. Donnenfeld has financial interest with Abbott Medical Optics (Santa Ana, Calif.), Alcon, and TrueVision. Contact information Agarwal: 91-44-2811-6233, dragarwal@vsnl.com Donnenfeld: 516-446-3525, eddoph@aol.com