The high-performance aspheric multifocal IOL platform of the AT LISA (Carl Zeiss Meditec) is designed for sub–2-mm microincision cataract surgery (MICS). LISA is an acronym for the IOL’s four unique principles: Light distributed asymmetrically, Independency from pupil size, SMP technology for ideal optical imaging quality with reduced light scattering, and Aberration-correcting optimized aspheric optic for better contrast sensitivity, depth of field, and sharper vision.
The original lens was designed with an asymmetrical light distribution of 65% for distance focus and 35% for near focus. This design improved intermediate vision and greatly reduced halos and glare compared with other multifocal IOLs. But the latest AT LISA lens design, the AT LISA tri 839MP (Table 1), goes one step further with its unique asymmetrical light distribution of 50%, 20%, and 30% for far, intermediate, and near foci, respectively. This breakdown of light distribution at each distance is designed to provide more satisfying and predictable visual outcomes for younger patients with active pupils at all distances (Figure 1). Visit eyetube.net/?v=fepoo to watch a video about the AT LISA tri.
LENS DESIGN
Other advantages of the AT LISA tri are detailed below.
Improved intermediate vision. The optical zone of the AT LISA tri has a 3.33 D near addition and a 1.66 D intermediate addition, providing patients with significantly improved intermediate vision without compromising near or far vision. Additionally, the refractivediffractive profile of the AT LISA tri is also designed to enhance intermediate vision over the central optic, increasing light transmittance to approximately 85.7% (data on file with Carl Zeiss Meditec).
Fewer visual disturbances. With fewer rings on the optical surface (Figure 2), the AT LISA tri reduces the risk for visual disturbances and has the potential to improve night vision compared with other multifocal IOLs. There are also no sharp angles on the optical surface, thus providing patients with ideal optical image quality, contrast sensitivity, and reduced light scattering.
High resolution in all lighting conditions. The images produced with the AT LISA tri are in high resolution at every distance (near, intermediate, and far), and in all lighting conditions. Patients can easily switch between foci at varying distances without the need for spectacle correction (Figure 3).
Maximum pupil independence. The AT LISA tri is independent of pupil diameter up to 4.5 mm. Its aberration-correcting aspheric optical design provides patients with sharp functional vision in all lighting conditions and across all distances. Air Force Resolution Target Test (AFT) for AT LISA tri 839MP and other bi- or trifocal IOLs at intermediate distance has shown that the AT LISA tri offers far better intermediate vision even in low light conditions (data on file with Carl Zeiss Meditec; Figure 4).
Conclusion
The latest AT LISA design, the AT LISA tri 839MP, has a unique asymmetrical light distribution design to produce more satisfying and predictable visual outcomes to younger patients. A number of surgeons already have experience implanting this lens in their patients, and patients have expressed their satisfaction with the quality of vision the AT LISA tri provides them.
The following articles, written by some of the first surgeons to implant the AT LISA tri in patients, are testament to the improvements of this lens design.
