Presbyopia-correcting IOL designs have evolved to the point that patients now can acquire a more natural range of vision, with near focal points located in a more functional intermediate range, and with fewer night vision symptoms. These positive trends, which began with the introduction of low-add multifocal IOLs on the Tecnis (Johnson & Johnson Vision) and AcrySof (Alcon) platforms, have helped our patients and our conversion rates.
I am more experienced with the Tecnis* platform image quality (referring to the platform’s spherical aberration and chromatic aberration properties).
The traditional +4.0-add multifocal IOL on this platform has a usable near-point at approximately 13 inches, which I have found to be closer than many patients want. Also, the out-of-focus near image can create a large symptomatic halo at night. The low-add Tecnis multifocals move the near-point out to about 17 or 20 inches with the +3.25 and +2.75 adds, respectively (Figure 1). Patients find these focal points more useful and the corresponding reduction in halo size improves night vision symptoms.
In July 2016, the FDA approved the Tecnis Symfony and Symfony Toric IOLs as the first in a new category of extended depth of focus (EDOF) IOLs. Rather than splitting light to two different focal points as a multifocal IOL does, EDOF IOLs provide a wider range of quality vision, over approximately 1.5 to 2.0 D of defocus.
MATCHING THE IOL TO THE PATIENT
While it is great to have multiple presbyopia-correcting options, these may leave some surgeons or referring doctors wondering which lens to recommend for which patients.
Both subjective and objective factors should be taken into consideration (Table 1). In my experience, most cataract patients want good quality vision, particularly in the far distance. The second desire is a continuous range of quality vision through intermediate and into near. If their surgeon asks preoperatively, they will find that most patients are good with occasionally wearing mild reading glasses to grasp small print.
|SUBJECTIVE FACTORS||OBJECTIVE FACTORS|
|• Interest in spectacle independence||• Preoperative visual acuity|
|• Concern about night vision symptoms||• Preoperative refraction|
|• Hobbies||• Astigmatism—degree and regular vs. irregular|
|• Personality||• Ocular surface health|
|• Expectations||• Severity and type of cataracts (nuclear, cortical or subcapsular)|
|• Satisfaction with first eye||• Comorbidities|
|• Height/arm length|
The Tecnis Symfony EDOF IOL is my choice for these patients, because its active correction of chromatic aberration provides them with excellent quality distance vision. With uncorrected binocular visual acuity of 20/20 for far and intermediate, and around 20/40 for near, patients can function well for most daily activities, including driving, using a computer, and looking at their tablet or smartphone.1 Night vision symptoms are milder than, but slightly different from, multifocal IOLs. Many patients note starbursts with a small array of faint concentric halos, but in my experience, these are quite tolerable — if patients are informed in advance.
I typically implant the dominant eye first, targeting plano, and then assess the patient’s satisfaction at the 1-day and 1-week postoperative visits to guide the IOL choice for the second eye. In most cases, I implant a second Symfony, targeting plano to -0.25 D. If the patient wants better near, however, I sometimes implant a low-add multifocal (typically) +3.25 in the contralateral eye.
This most frequently occurs with low myopes who are accustomed to removing their glasses to read, so I do spend extra time preoperatively to set proper expectations with these patients.
I might consider starting with a low-add multifocal in an older patient who does not drive much at night and reads books a lot, or someone who has a specific fine-vision hobby, such as knitting or building model airplanes.
Presbyopia correction for astigmatism: Filling the gap
By Preeya K. Gupta, MD
The introduction last year of the first extended depth of focus IOL in the United States, which comes in sphere and toric powers, eliminated the choice problem that cataract surgeons and many of their patients traditionally faced between a toric IOL and presbyopia correction.
The reality is that most patients who are interested in a premium lens want good uncorrected vision at both distance and near — and that means, in many cases, fixing their astigmatism. The majority of patients presenting for cataract surgery have at least some corneal astigmatism, and 41% of them have visually significant astigmatism ≥ 0.75 D.1
In my practice, we have been using the Tecnis Symfony toric (J&J Vision), and our conversion rate to premium IOLs is increasing because my staff and I can talk about presbyopia correction more confidently without first assessing how much astigmatism the patient has.
DETERMINING YOUR MO
- Low astigmats (<1.00 D). Low-add multifocal IOLs have performed well for those with low astigmatism. But, because we need to manage even small amounts of astigmatism so these lenses perform as intended, I typically have paired these IOLs with femtosecond laser astigmatic keratotomy incisions in patients who have with-the-rule astigmatism. I am more cautious about incisional correction in patients with against-the-rule (ATR) astigmatism, as these incisions are mostly effective for much lower levels of ATR astigmatism.
- Moderate astigmats (1.00-2.00 D). I think a toric IOL provides more stable correction of astigmatism over time in this group.2 So, prior to the availability of a toric EDOF lens, I was less willing to offer presbyopia correction to this group of patients.
- High astigmats (>2.00 D). These patients assume they will always have to wear glasses. Satisfaction levels were high with toric IOLs in this group, but my patients have responded positively to us offering them distance and intermediate to near correction.
The Symfony is a single-piece IOL with similar characteristics to other Tecnis IOLs. It has been reported to be tolerant to some residual error. Although I find it to be more forgiving than traditional multifocal IOLs, I still recommend a conservative approach to integrating Symfony into the practice.3
Surgeons should initially follow the same fundamental principles that apply to multifocal IOLs: select patients with no retinal pathology or concomitant ocular disease; treat the ocular surface; manage astigmatism; and perform meticulous preoperative measurements and careful surgery. Because postoperative contrast sensitivity seems to be similar to that of a monofocal IOL (Figure 1), we may be able to offer this lens to patients with mild ocular surface disease or early macular degeneration, but results in such eyes have not been published. Also, one’s first 50 cases are probably not the best time to test the limits of the technology so one can become comfortable with the technology.
MONOCULAR CONTRAST SENSITIVITY
When setting expectations. I tell patients that EDOF lenses offer freedom from glasses for distance and intermediate tasks, though they may need reading glasses for near work. Most of my patients do not need reading glasses full time, but I would rather they anticipate using them for some tasks.
Also, I talk about potential night vision issues with Symfony candidates. The clinical trial data suggest few patients actively complained about night vision symptoms (Figure 2). This IOL has a different night vision profile than low-add multifocal lenses. Qualitatively, the symptoms seem to be less bothersome for most patients; my patients describe something more akin to starbursts or light scattering rather than halos. Most patients tolerate night vision symptoms well, but I still counsel them about it before surgery as patient selection is key. Patients who are very particular about seeing any visual phenomenon such as glare or halo are not good candidates for presbyopia correcting technology. Clinicians should expect that a small percentage of patients will not be able to tolerate alterations in night vision quality.
LOW VISUAL SYMPTOMS
It is certainly possible to mix and match Symfony (spheric or toric) IOLs with either a monofocal or a low-add multifocal in the fellow eye to achieve the desired refractive outcome. My personal preference is to implant IOLs with the same optics in both eyes — I generally do not mix and match. I target a slightly myopic outcome of -0.25D in the nondominant eye and plano in the dominant eye, which seems to enhance the near vision somewhat.
It will be interesting to see future published studies that compare results in bilateral vs. mix/match or plano vs. micromonovision targets, as well as outcomes in more complex eyes that we previously would not have considered suitable for multifocal IOLs. OM
- Ferrer-Blasco T, Montés-Micó R, Peixoto-de-Matos SC, et al. Prevalence of corneal astigmatism before cataract surgery. J Cataract Refract Surg. 2009;35:70-75.
- Mohammad-Rabei H, Mohammad-Rabei E, Espandar G, et al. Three Methods for Correction of Astigmatism during Phacoemulsification. J Ophthalmic Vis Res. 2016 Apr-Jun;11:162-167.
- Cochener B. Tecnis symfony sntraocular lens with a “sweet spot” for tolerance to postoperative residual eefractive errors. OJOph. 2017. 7;1:14-20.
REACHING PATIENTS AND OPTOMETRISTS
The availability of low-add and EDOF IOLs have simplified the discussion with patients because these devices can provide the vision ranges that matter most to each patient. The addition of toric EDOF IOLs also means we no longer have to choose between correcting presbyopia and astigmatism.
With new presbyopia-correcting IOLs representing a significant step forward in our treatment of presbyopia, it is important to ensure that referring optometrists are aware of the changed landscape.
Rightly or wrongly, many optometrists have written off multifocal IOLs for their patients based on experience with older-generation multifocal IOLs and multifocal contact lenses. The EDOF category, in particular, is characteristically and functionally unlike their prior clinical experience and therefore more compelling to doctors who have not looked seriously at presbyopia correction for some time.
Since I began implanting EDOF IOLs, my presbyopia-correcting IOL conversion rate has doubled and my overall premium IOL conversion rate has increased by one-third. I have many patients who are happy with their presbyopic correction. Refractive-cataract surgeons can finally deliver on the promise of reduced spectacle dependence with low-add and EDOF IOLs. OM
- Cochener B; Concerto Study Group. Clinical outcomes of a new extended range of vision intraocular lens: Multicenter International Concerto Study. J Cataract Refract Surg. 2016;42:1268-1275.