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    Dual-optic accommodating IOL often preferred

    Monza, Italy—Current multifocal IOL technology, which is mainly diffractive technology, is very effective for providing good near vision and high rates of spectacle independence for patients undergoing cataract surgery and seeking presbyopia correction. However, there are a number of penalties associated with diffractive IOL technology, said Matteo Piovella, MD.

    Therefore, considering the drawbacks and unless he needs to correct astigmatism simultaneously, the dual-optic accommodating IOL (Synchrony, Abbott Medical Optics) is generally his preferred implant for patients interested in a presbyopia-correcting IOL, said Dr. Piovella, founder and scientific director, Centro Microchirugia Ambulatoriale, Monza (Milan), Italy.

    Dr. Piovella explained that there are compromises in both quantity and quality of vision with diffractive multifocal IOL technology that do not occur with the dual-optic accommodating IOL. Diffractive multifocal IOLs are uniquely associated with loss of contrast sensitivity (up to 30%) and have a greater potential for halos and glare than the dual-optic accommodating IOL. In addition, the vision outcome is less sensitive to residual refractive error using the dual-accommodating IOL than with diffractive multifocal IOLs. Dr. Piovella said that in his hands, the rate of postoperative Nd:YAG laser capsulotomy is also far less in patients receiving the dual-optic accommodating IOL compared with the market leader in diffractive multifocal IOL technology.

    On the other hand, the likelihood of needing to wear glasses sometimes for near vision is greater with the dual-optic accommodating IOL than with available multifocal implants.

    “For demanding patients who want a full range of functional vision yet can accept wearing spectacles sometimes for near vision but are concerned about halos and glare after hearing the experience of others with a diffractive multifocal IOL implanted, the dual-optic accommodating IOL is my preferred implant for presbyopia correction,” said Dr. Piovella.

    “In contrast, some patients have such a strong desire for spectacle-independence that they would be unhappy needing glasses for near vision and are ready to tolerate some loss of contrast sensitivity and potential halos and glare,” he said. “A multifocal IOL is a better choice for these patients, and if the patient has more than 0.75 D of corneal astigmatism, it is mandatory to implant a toric multifocal IOL.”

    Dr. Piovella added that another factor to consider when weighing different presbyopia-correcting IOL options is that accurate refractive outcomes are essential when implanting a multifocal IOL because even a small error has a significant impact on visual function.

    “With multifocal IOLs, a 0.75-D spherical equivalent error generates loss of 1 line of visual acuity, and significant residual cylinder error reduces contrast sensitivity and induces halos and glare,” he said.

    Reviewing the characteristics of current diffractive multifocal IOLs, Dr. Piovella noted that use of the term multifocal to describe the ReSTOR multifocal IOL (Alcon) is questionable because the lens has a diffractive bifocal technology that splits the light only for far and near focus. Not only is there no provision for intermediate focus, but because of its distance dominant design, there is substantial light loss with small to medium pupils, and this IOL may not provide sufficient quality of vision when a residual postop refractive error is more than 0.50 D.

    The apodized diffractive design of the ReSTOR IOL does theoretically help to reduce halos, but complaints of severe/very severe halos can still occur in a significant numbers of patients with diffractive multifocal technology implanted despite very positive results achieved by the large majority of the patients, Dr. Piovella said.

    Similarly, the AcriLisa multifocal IOL (Carl Zeiss Meditec), which is another popular multifocal IOL in Europe, has a distance dominant design with no provision for intermediate vision. The amount of light loss with the AcriLisa multifocal IOL is somewhat reduced relative to the ReSTOR multifocal, but there is still a significant proportion of light (15%) outside the range of vision regardless of pupil size.

    The Tecnis multifocal IOL (Abbott Medical Optics) has a full diffractive posterior surface that allows for visual performance that is independent of pupil size at all light conditions. However, intermediate vision still suffers with this design because the light is split 50/50 for far and near, and this IOL is also associated with some loss of light, Dr. Piovella said.

    The OptiVis multifocal IOL (Aaren Scientific) introduces a new concept in optic design that minimizes loss of light. The intermediate zone has improved apodization that appears successful in reducing nighttime dysphotopsia and loss of contrast sensitivity, and this lens design also provides some intermediate light distribution.

    Dr. Piovella said that in contrast to the diffractive multifocal IOLs, the dual-optic accommodating IOL is not associated with loss of light because it uses 100% of the light at any distance. The lens provides a full range of vision, suffers no penalization of contrast sensitivity, and does not lead to complaints about severe/very severe halos and glare. However, some patients with the dual-optic accommodating IOL implanted have slight dysphotopsias and some may need +1 D of add to read very small print because the accommodative technology is less effective for near vision compared with multifocal IOLs.

    “However, with the dual-optic accommodating IOL, patients are able to use the computer or do other intermediate vision tasks without glasses,” Dr. Piovella said. “In addition, a next-generation dual-optic accommodating IOL with an aspheric zone on the front optic has been announced for 2012 and is designed to provide enhanced near vision without compromising quality of vision.”

    Another advantage of the dual-optic accommodating IOL is that accommodative technology quality of vision is similar to that associated with monofocal IOLs, and in the event the patient goes on to develop macular degeneration this situation remains neutral. The diffractive multifocal IOLs are currently contraindicated in patients with macular degeneration, Dr. Piovella said.

    Furthermore, the need for Nd:YAG capsulotomy is far less in patients with the dual-optic accommodating IOL.

    “Surgeons planning to implant a multifocal IOL need to consider that diffractive technology is much more sensitive to posterior capsule opacification, and slight loss of posterior capsule transparency is effective in decreasing near vision performance,” Dr. Piovella said. “Therefore, in my experience, about 35% of patients with a diffractive multifocal IOL implanted need early Nd:YAG laser capsulotomy, within 1 year, to maintain their visual efficiency.

    “In contrast, in a series of 33 patients followed to 1 year after implantation of the dual-optic accommodating IOL, I have only performed Nd:YAG laser capsulotomy in two (6%) eyes.”

    Dr. Piovella acknowledged that implantation of the dual-optic accommodating IOL requires a relatively large, 3.75-mm incision. However, he says that since 1988, he has accumulated a huge series of patients who underwent phacoemulsification with implantation of a rigid 5.0-mm IOL, and the data collected in these eyes document that the large-incision surgery was performed without inducing significant astigmatism in more than 90% of the patients.

    Dr. Piovella is a consultant to Abbott Medical Optics.

    For more articles in this issue of Ophthalmology Times eReport, click here.

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