New lens seeks to solve problems of presbyopia-correcting IOLs
by Frank Goes Jr., MD
Frank Goes Jr., MD
Table 1: Binocular uncorrected visual acuity
Figure 1: Percent of patients able to perform daily activities without glasses
Figure 2: Percent of patients reporting that activities are easy/acceptable to do postop Source (all): Frank Goes Jr., MD
Lens shows good uncorrected intermediate vision and a near- absence of unwanted visual symptoms in European population
An ongoing European multisite study is evaluating the results of a new type of presbyopia-correcting IOL. The Tecnis Symfony lens (Abbott Medical Optics, Abbott Park, Ill.) is the first extended range of vision lens. It relies on a diffractive echelette design that elongates the eyes focus to extend the range of continuous clear vision. The lens platform is the same as that of the Tecnis 1-piece, a hydrophobic acrylic with a known track record of stability and excellent optics. It is CE marked and commercially available in some European countries. It is important to recognize that this lens does not fit into any of our previous presbyopia-correcting IOL categories. It is not an accommodative IOL or a multifocal. While a multifocal IOL has 2 or 3 distinct foci, an extended range of vision lens elongates the focus of the eye; in the case of the Tecnis Symfony, it delivers a continuous, full range of high quality vision, much like the human crystalline lens. It also differs from extended depth of focus lenses, which provide some intermediate vision but no near.
In the European study, 150 subjects undergoing bilateral cataract surgery or clear lens extraction (CLE) with implantation of the Tecnis Symfony lens have been enrolled. The study is designed to measure reading ability, functional near vision performance, image quality at different distance ranges, and patient-reported outcomes, such as satisfaction and the ability to function comfortably without eyeglasses. Interim results for 82 subjects who had reached the 1-month postoperative visit were recently reported.
Patients in the study were able to maintain functional vision of 20/40 or better throughout the range from distance to near vision, through 2.0 D of defocus on average. Binocular uncorrected visual acuity results are shown in Table 1. The majority reported never or rarely using glasses and said they were able to perform daily activities at near, intermediate, and far distances (Figure 1), including key activities without glasses (Figure 2).
Nearly all (98%) said they would recommend the TECNIS Symfony IOL to family and friends.
Satisfaction has been high, even among the CLE subjects, who are generally regarded as more difficult to satisfy because they have good vision before surgery. Very high percentages98% to 99%say they do not have any severe halo, glare, or starbursts, a rate that is comparable to what we see with monofocal IOLs. Of the limited number of subjects (7) that I enrolled in the study and have personally followed, none is wearing glasses at any distance. These are promising interim results, and I look forward to the final results once all the subjects have reached 1-month follow-up.
Finding its place
At Goes Eye Centre, we have implanted nearly every presbyopia-correcting lens on the market over the past 15 years, and we regularly recommend multifocal IOLs. However, there are 2 major disadvantages of the classic multifocal IOLs. The first is that intermediate vision is weaker than we would like. This is especially true with the older bifocal multifocal lenses, which have excellent distance and near vision, but a weaker intermediate distance. In my experience, patients often complain about this gap. We know that intermediate vision is critical for spectacle-free functioning. We use intermediate vision to cook, see the food on our plates, read labels in a store or supermarket, and work on a tablet or computer. True near tasks such as reading a newspaper or book have been declining in importance for many people. Instead, we read books and newspapers on a tablet or a desktop computer.
The second disadvantage of multifocal IOLs is the potential for glare, halo, or other unwanted visual effects. Although these are usually mild and improve with neuroadaptation, many patients are afraid of these side effects and unwilling to risk the chance that they might experience more severe glare and halo. I think the fact that the extended range of vision lens provides a substantial improvement in the range of vision while still minimizing undesired halos or glare will make it appealing to patients. Of course, the Tecnis Symfony also has limitations. With this lens, I cannot promise patients 100% reading capability without glasses because it does not extend the range of 20/20 vision all the way to the traditional reading distance of 4045 cm. However, it extends the range of vision by about 1.0 D throughout the entire defocus curve, from near to far, providing mean acuity of 20/40 or better all the way to 40 cm. To improve a patients near acuity, we have the option of micro-monovision. I like to correct the dominate eye for emmetropia and the nondominant eye for 0.50 D. This small gap is easily tolerated and does not cause the problems we typically associate with monovision, but it is just enough to improve visual acuity in the near range and allow most patients to read without spectacles.
Just like multifocal IOLs, the quality of vision with extended range of vision lenses will suffer if there is residual astigmatism or residual sphere in the dominant distance eye, so it is important to have a plan for correcting corneal astigmatism. Ultimately, I think extended range of vision IOLs will prove to be an excellent option for our patients who want natural feeling, continuous vision, and who want to avoid visual side effects.
Editors note: Dr. Goes is medical director of the Goes Eye Centre in Antwerp, Belgium. He has no financial interests related to this article.