Our optimal objective for presbyopia and cataract patients is to provide a full range of focus with the least possible compromise in quality of vision. I customize IOL selection and use a mix-and-match approach to achieve this goal of functional spectacle independence while minimizing compromises in quality of vision.
The process of learning which IOLs work for which patients takes time, and this is especially true for new IOL technologies for which there are not yet extensive clinical data. For instance, I initially implanted the Tecnis Symfony Extended Range of Vision IOL (Abbott Medical Optics; Figure 1) in combination with a multifocal IOL, but I switched to bilateral implantation in many of my refractive lens exchange and cataract surgery patients because I realized that the lens’ optics create fewer tradeoffs to the quality of vision than multifocal IOLs.
In the end, it is all about patient satisfaction. The first key to achieving optimal patient satisfaction is proper patient selection; the second is having meaningful conversations about IOL technologies with patients. When patients understand what kind of vision they can expect after surgery, they are more likely to be happy with their results.
A few case examples may help to illustrate these points.
THREE PATIENT TYPES
The ideal candidate. Patient C.W. is a 67-year-old lawyer. He and his wife enjoy weekend trips to the countryside. Other than cataract and high blood pressure, his ocular and systemic histories are unremarkable. After reviewing the patient education materials we provided to him, Patient C.W. expressed an interest in a presbyopia-correcting IOL.
We conducted a baseline panfocal visual acuity assessment, a series of measurements that we do before and after surgery in each eye. I have found that a score of 20/30 or better at all of the panfocal measurement points (Table 1) is consistent with a patient’s ability to perform a wide range of tasks with complete spectacle freedom. It also helps me to customize lens choices.
For this patient, I recommended bilateral implantation of the Tecnis Symfony IOL. I like to describe this lens to patients as a mini-zoom lens. Just like the zoom on a camera, it provides the same sharp, in-focus image at any point over the range of the zoom. I told Patient C.W. that it would allow him to see clearly without glasses for most of his leisure activities and daily work including use of a smartphone, tablet, and computer, as this was a priority for this professionally active patient. I did not promise that he would never need glasses. I always ask questions like, “If you have to wear glasses for certain tasks, would you rather it be for reading a novel in bed or for using the computer and shopping?” Most people will choose the former, as Patient C.W. did.
Figure 1. An echelette design introduces a novel pattern of light diffraction that elongates the focus of the eye, resulting in an extended range of vision.
After surgery on his first eye, I asked Patient C.W. how his near vision was. He said it was fine for everything except prolonged reading, as I had anticipated from our panfocal testing results. When it came time for second-eye surgery, I therefore aimed for a micro-monovision target of -0.50 D. This target carries none of the disadvantages of true monovision but provides an extra edge for reading. After this procedure, Patient C.W. was spectacle independent and satisfied with his results.
The noncandidate. Patient L.S. is a 73-year-old woman with age-related macular degeneration (AMD). She would love to be less spectacle dependent, but when she inquired about suitability for “the new lenses” she had heard about, I was not yet comfortable recommending Symfony—I certainly would not implant any other presbyopia-correcting IOL, as all involve compromises in contrast sensitivity that are not acceptable for a patient with limited vision from AMD.
Given what we know about its optics and its quality of vision similar to that of a monofocal lens, I think the Symfony IOL may prove to be a good option in patients with AMD or other significant comorbidities, such as severe glaucoma or uveitis. However, until we have more information about its performance in such eyes, I erred on the side of caution and selected a monofocal IOL for Patient L.S. instead.
The patient who is committed to another option. Patient D.A. came to me for cataract surgery, ready to have the same lenses his wife got last year. I had put a monofocal toric in her dominant eye and a multifocal toric in her nondominant, and she was thrilled with the results. Now that it was her husband’s turn, he wanted the same lenses but asked whether I could do anything about the glare that had bothered his wife in the early postoperative period. Patient D.A. does a lot more driving than his wife and wondered whether he was likely to experience glare and halos.
When I have to tell patients that they are not good candidates for the IOL their friend or relative got, I use that as an opportunity for patient education. This is a good time to tell them about how we can customize the lens choice to their particular pair of eyes and lifestyle.
AT A GLANCE
• A visual acuity of 20/30 or better at all of the panfocal measurement points is consistent with a patient’s ability to perform a wide range of tasks with complete spectacle freedom.
• The extended range of vision and minimal compromise in quality of vision of the Symfony IOL make it easier to explain its pros and cons when compared with multifocal IOLs.
I explained to Patient D.A. that we did not need to address astigmatism as we had in his wife’s case. I recommended implanting the the Symfony IOL and explained the zoom lens analogy mentioned previously, but I also gave him some reassurance that, compared with multifocal IOLs, the tradeoffs in quality of vision are minimal. Data to date show that contrast sensitivity and degree of photic phenomena with the Symfony IOL are similar to those of a monofocal lens, which makes it a great choice for someone who wants to avoid the potential for night driving problems.1-3 He was delighted to hear that news. In fact, both spouses left the consultation satisfied that they had gotten the best fit for their eyes and the best lenses available at the time of their respective surgeries.
I find that patient conversations are much easier since the introduction of the Symfony lens. The extended range of vision and minimal compromise in quality of vision make it easier to explain the pros and cons of this lens compared with multifocal lenses. I also spend less time explaining the gaps or weaknesses in the range of vision characteristic of multifocal lenses. Most people who are not familiar with optical principles find it difficult to grasp how they could have blurred vision at intermediate distance when they see well at distance and near, as often happens with a multifocal IOL. In those cases, we have to be careful to set expectations correctly to avoid disappointment.
The Symfony Extended Range of Vision IOL is not perfect, but it requires far fewer visual compromises, and, thus, there is much less to explain. My results to date show that patients have seamless continuous vision from distance to intermediate plus functional near vision. The fact that some patients do not achieve good enough near vision for prolonged reading or fine print is easily addressed with a micro-monovision target of less than -0.75 D in the second eye. n
1. Data on file, Abbott Medical Optics. 2014CT0002 - Symfony Harmony EMEA Trial
2. Data on file, Abbott Medical Optics. 166, Extended Range of Vision IOL 3-Month Study Results (NZ).
3. Weeber HA, Piers PA. Theoretical performance of intraocular lenses correcting both spherical and chromatic aberration. J Refract Surg. 2012;28(1):48-52.
Milind Pande, DO, FRCS, FRCOphth
- Consultant Ophthalmic Surgeon and Medical Director, Vision Surgery & Research Centre, East Yorkshire, England
- Financial disclosure: Consultant (Abbott Medical Optics)