EyeWorld Asia-Pacific December 2012 Issue

25 EWAP CATARACT/IOL December 2012 Combined Zernike 3rd and 4th order aberrations will help determine who is most likely to be dissatisfied with a multifocal IOL. Source: Marc Michelson, MD Linking pre-op HOAs to post-op satisfaction rates by Michelle Dalton EyeWorld Contributing Editor New data suggests that 3rd and 4th order Zernike terms are most likely to influence patient satisfac- tion with premium lenses T he higher the pre-op root mean square (RMS) value for combined 3rd and 4th order Zernike terms, the greater the intolerance for multifocal lenses will be, according to a paper presented at this year’s ASCRS• ASOA Symposium & Congress.1 These findings may help explain why one group of patients does well with multifocal lenses but another group does not, the study authors say, and lends credence to the argument that every cataract patient should undergo a wavefront analysis. According to Marc Michelson, MD , associate clinical professor of ophthalmology, University of Alabama School of Medicine, Birmingham, Ala., USA, and in private practice, Michelson Laser Vision Inc., Birmingham, Ala., USA, and Alabama Eye & Cataract Center, Birmingham, Ala., USA, “there is a significant degree of dissatisfaction among people who get premium lenses, and surgeons implant these lenses without knowing who is tolerant and who may not be.” Light scatter can lead to a reduction of optical quality, he said, and 25% of patients who have multifocal lenses report some degree of dysphotopsia. In 2007, Rocha et al. 2 found different types of lenticular opacities induce different wavefront aberration profiles, and in 2008, Tong et al. 3 found changes in corneal wavefront aberrations were dependent upon incision size, with microincisions minimizing the effect on optical quality when compared to small incision cataract surgery. And at this year’s ESCRS meeting in Milan, Varavka et al. 4 will present their study findings on coma and lens dislocation. Dr. Michelson said the relationship between aberrations, Hiroko BISSEN-MIYAJIMA, MD, PhD Department of Ophthalmology, Tokyo Dental College Suidobashi Hospital 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo 101-0061 Japan Tel./Fax no. +81-3-5275-1912 bissen@tdc.ac.jp T he key for successful implantation of a multifocal IOL would be the reduction of the unhappy patients to nearly zero. Since the optical property of the diffractive multifocal design is complicated, the visual outcomes which directly connect to the patient’s satisfaction rate can be easily influenced by other conditions, such as tear film, corneal aberration, and posterior capsular opacity than those with monofocal IOLs, Dr. Michelson mentioned that 25% of patients reported some degree of dysphotopsia following the implantation of a multifocal IOL. In our series of over 700 patients, 5% were not satisfied with their quality of vision. We all know these complaints are more severe than those we have experienced with patients with monofocal IOLs. Under these circumstances, any tool to predict the visual outcome following the implantation of a multifocal IOL will be a great help. Corneal astigmatism is a well-known factor to reduce the uncorrected distance and near visual acuities in eyes with multifocal IOLs. Surgeons can easily reduce the amount of astigmatism at the time of surgery or afterward. The concept of higher order aberration (HOA) quickly expanded in the field of laser in situ keratomileusis (LASIK). Measuring HOA using wavefront sensors is necessary not only before LASIK surgery, but also before cataract surgery to select the appropriate IOL from the variety of IOLs with different optical characteristics such as aspherical, toric and multifocal IOLs. KR- 1W (Topcon, Tokyo, Japan) has unique software called IOL selection map which provides the information of HOA which will be helpful to select the IOL. The idea is similar to what Dr. Pepose mentioned. Most surgeons agree that the multifocal IOL is not indicated for the eye with a highly aberrated cornea. In our practice, the top 1% of the most dissatisfied patients showed a relatively low amount of HOA. Thus, evaluating HOA before surgery will reduce the number of unhappy patients; however, we should know that this is not the complete solution. In the near future, the number of cataract surgeries in eyes with previous LASIK will increase and those patients who wish for spectacle freedom will be interested in the multifocal IOL. Even with the preferable results reported by wavefront- guided LASIK, measuring HOA is mandatory when we consider multifocal IOLs. Recent development of IOL power calculation brought reasonable postoperative refraction in eyes that received LASIK. The next step will be the appropriate selection of patients. The influence of coma and trefoil are discussed in this article. Further investigation and understanding of HOA seems to be the key for better visual quality following IOL implantation. Editors’ note: Prof. Bissen-Miyajima declared no financial interests related to her comments. Views from Asia-Pacific continued on page 26