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Two clinicians explore why an optimal visual solution for patients may be using both a low-add multifocal and an extended-range-of-vision lens.
Take-home message: Two clinicians explore why an optimal visual solution for patients may be using both a low-add multifocal and an extended-range-of-vision lens.
By Jeffery J. Machat, MD, FRCSC, and Sondra Black, OD, Special to Ophthalmology Times
Toronto-For surgeons who may have had a bad experience with earlier multifocal IOLs and vowed not to implant another presbyopia-correcting lens, times have changed.
The latest presbyopia-correcting lenses are not just incrementally better-they represent a dramatic improvement in patient satisfaction, night vision quality, and functional vision. It would be a mistake not to revisit the category, especially since surgeons can now mix and match within a single lens platform to meet a patient’s visual goals.
A variety of mix-and-match strategies have been used in the past. Surgeons have tried to combine various multifocal lenses to maximize functionality, with limited success. A year ago, we had been using a combination of the Crystalens (Bausch + Lomb) for the dominant eye and a Tecnis Multifocal +4.00 add (Abbott Medical Optics) for the non-dominant eye, to give patients both reading and intermediate vision, as well as their distance. Both of these lenses had significant drawbacks, though.
Now, two lenses that have recently been introduced to market-the Tecnis Multifocal low add and the Tecnis Symfony extended range of vision IOL (Abbott Medical Optics)-seem to provide the ideal combination.
When the Symfony lens was introduced in Canada, we began implanting it bilaterally, with great results. It provides about 1.5 D of accommodative amplitude, so patients could be counseled to expect to use a pair of +1.00 readers for small print.
Then, we began trying to give patients a “boost” for their near vision by implanting a Symfony lens in the dominant eye for intermediate and a +3.25 low-add multifocal in the non-dominant eye for near. Both eyes, together or individually, see really well at distance.
A prospective study of outcomes with this combination is under way, but after implanting 800 of these lenses in the past year, this may be the best combination available for a full range of vision.
For surgeons who do not yet have access to the Symfony lens, the combination of a 2.75-add lens in the dominant eye and 3.25-add lens in the non-dominant eye could achieve similar results.
A surgeon who may be apprehensive about getting back into multifocal IOL implantation might want to start with bilateral implantation of the Tecnis Multifocal 2.75 add or the ReStor 2.5 add.
These low-add lenses are well tolerated, and they provide good distance vision and practical intermediate.
Depending on the patient, they may provide sufficient reading vision, as well. It is a good segue into other combinations. Patients will also experience less halo and glare than with the higher-add multifocal lenses. It is a clinically significant improvement.
The best way to start mixing and matching is to implant a Symfony or low-add lens (2.75) in the dominant eye first. At the 1-week postoperative visit, use the patient’s assessment of how he or she is functioning for near and intermediate tasks to guide the decision of what to implant in the second eye. If the patient is already satisfied with near vision, put the same lens in the second eye. If he or she wants better near, choose a higher add (3.25) for the second eye.
There is exponentially less chance of having a patient who is unhappy with results if the surgeon starts with low-add (2.75) or Symfony lenses and adjusts from there to achieve the functional range of vision that meets the patient’s needs.
Another concern with earlier presbyopic lenses was the potential for nighttime dysphotopsias. With a +4.00 add, when the patient focuses on distance, the reading vision is out of focus. The difference between the distance and the near focal points is so large that there is a large blur circle, which is what causes halo and glare.
With a low-add lens, the blur circle is smaller. While halos and glare may still be present, they are much less bothersome and patients seem to tolerate these low-add multifocal IOLs better.
The Symfony design goes even further toward eliminating night vision problems. It has an echelette design in which each ring has increasing foci. This provides a continuous curve rather than two distinct focal point peaks. Patients can hold something at intermediate range and bring it in closer while continuing to read with ease, which is a more natural visual experience. Clinical trial results demonstrate that night-vision symptoms are mild to nonexistent.
Because of these important improvements in lens quality and functionality, surgeon confidence in and market penetration of presbyopia-correcting IOLs should significantly increase over the next 2 to 3 years.
It cannot be stressed enough the difference between low- and high-add multifocal lenses. Anyone who begins implanting low-add multifocal IOLs and talking to patients postoperatively about the experience will realize how much better they are. The add powers can already be mixed and matched to achieve an excellent range of vision and high satisfaction for most patients. Where the Symfony lens is available, the combination of it with a low-add multifocal may be ideal.
1. Questionnaire/good history. Patients’ responses will indicate whether they want to be completely spectacle independent or are willing to wear glasses at some distances; what activities they do regularly; and how much of a perfectionist they are.
2. Astigmatism. Visually significant astigmatism affects options. New low-add and extended range-of-vision lenses do not come in a toric option yet so it will be necessary to correct the astigmatism with femtosecond arcuate incisions, manual LRIs, or laser vision correction if the patient wants presbyopia correction.
3. Physical size. Take into consideration whether the person is short or tall and has long or average length arms. A tall man with long arms may do best with Symfony in both eyes.
4. Near preference. During the preoperative workup, patients are given a reading card and asked: “In an ideal world, where do you want to read?” The reading card has a string with colored beads at 33 cm (to correspond to a +4.00 add), 40 cm (+3.25 add), and 50 cm (+2.75 add). Present the reading card upside down. When patients flip it right side up, they will naturally adjust it to their reading distance. If a reading distance of 40 cm, the Symfony/+3.25 add combination is likely ideal.
No matter what lens is chosen, surgeons do not make a promise for 100% spectacle independence, and still tell patients to expect to need a pair of reading glasses for threading a needle or reading fine print.
Jeffery J. Machat, MD, FRCSC
Dr. Machat is chief medical officer, Crystal Clear Vision, Toronto, which is part of the NVision Eye Center Network.
Sondra Black, OD
Dr. Black is vice president and clinical director, Crystal Clear Vision.