David Teenan FRCS(Ed), FRCOphth

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Retrospective data analysis reveals that several different combinations of certain IOLs provide excellent results.

As the largest provider of premium IOLs in the UK, Optical Express has a long history of using advanced technology to help patients see and function well after surgery.

With the proliferation of new presbyopia-correcting IOLs, we have offered patients a range of options over the years, from bilateral high, low or mid-add multifocal IOLs to extended depth of focus (EDOF) IOLs, and various combinations of these technologies.

Recently, we conducted a retrospective analysis of clinical and patient-reported outcomes with three different combinations of presbyopia-correcting IOLs.

We looked at a large data set of patients who had undergone bilateral lens surgery at Optical Express over a 4-year period between 2015 and 2018 and who had at least a 3-month follow-up. We compared three different lens combinations used during this time period: 3,362 patients with bilateral Tecnis Multifocal +2.75 (the lowest available add power for this lens); 1,250 patients with the Tecnis Symfony EDOF lens in one eye and the Tecnis Multifocal +2.75 in the other; and 665 patients with Symfony in one eye and the mid-add Tecnis Multifocal +3.25 in the other.

Demographic characteristics and preoperative refractions were similar among all three groups. The lens groups were not random, however. Lens selection was determined preoperatively, based on conversations with the patient about his or her visual requirements and goals, as well as anatomical or optical factors relevant to the decision.

Clinical results Subjects did very well with all three lens combinations. At 3 months, 62.4% were seeing 6/5 (20/16) or better and 86.4% were seeing 6/6 (20/20) or better binocularly at distance without correction. There were no statistically significant differences in the rate of 20/20 uncorrected distance visual acuity (UDVA) among the groups. The Symfony/3.25 group was more likely to have 20/40 or better UDVA.

At the 3-month timepoint studied in this analysis, some patients may still have had residual refractive error. Secondary procedures to enhance the refractive effect, if necessary, had not yet been performed. Uncorrected near visual acuity (UNVA) was N5 (J6) or better in 73.4% of all patients, regardless of the lens combination (Figure 1).

The Symfony/3.25 and bilateral 2.75 groups were more likely than the Symfony/2.75 group to have UNVA of N6 (J8) or better.

The manifest refraction spherical equivalent (MRSE) was very good, with 76.6% of all patients being within 0.5 D of emmetropia. The bilateral 2.75 patients were statistically significantly more likely than either of the EDOF/multifocal combinations to be within 0.5 D. In terms of corrected distance visual acuity (CDVA), more than 90% of patients gained lines or maintained the same CDVA after surgery.

Of all the patients, 16.9% lost one line of vision; 2.3% lost two lines; and 0.5% lost more than two lines. There was no statistically significant difference among the groups in the loss of more than two lines. There was no difference in complication rates, so safety was excellent with all three IOL combinations.

Overall, patients with all three IOL combinations were happy with their outcomes, with 90.9% being satisfied or very satisfied, and even higher percentages saying they would have the procedure again or recommend it to friends and family.

There was no statistically significant difference between groups in the satisfaction rate. Overall, more than half the patients reported experiencing no postop glare, halo or starburst at all. However, at the other end of the spectrum, as we have come to expect with presbyopia-correcting IOLs, approximately 18–20% of patients reported moderate to severe glare, halos and starbursts after bilateral lens surgery.

Although I expected to see a lower rate of photic phenomena in the EDOF/multifocal combination groups, this turned out not to be the case. Rates for moderate to severe symptoms were similar across all three groups.

However, we would have expected to see these decrease by 6 or 12 months postop, due to neuroadaptation and (where needed) enhancements. Some patients experienced symptom resolution after surgery while others worsened, similar to what has been reported in other large studies of refractive procedures.

About 15% of all patients reported a 2-point increase in the symptoms compared to preoperatively, while 10–12% reported a decrease in symptoms from preop to postop. About 9% of patients reported moderative to severe difficulty with night driving after surgery; about 6% said night driving worsened postop compared to preop. Patients in the bilateral 2.75 group were least likely to report no glare, but otherwise, patient reports of visual disturbances and night driving experience were quite similar across the three groups.

Although all three IOL combinations produced good results and would be good options for patients, the bilateral low-add multifocal group had the best near vision outcomes and seemed to be the more highly preferred option by both surgeons and patients.

We are fortunate to have presbyopia-correcting IOLs in a range of add powers and optical designs that provide the opportunity to customise the IOL choice to the patient needs. Based on the data in this analysis, I tend to rely most heavily on bilateral low-add multifocal IOLs for the majority of my patients. Implanting the same lens bilaterally helps to cut down on patients comparing the IOL performance between their two eyes.

However, there are certainly still patients for whom it may make sense to personalise the refractive outcome by combining two different IOLs. In particular, this may be warranted when the results of the first eye are not as desired.

I usually implant the nondominant eye first. If the patient is dissatisfied with the near vision or already symptomatic with glare and halo, for example, I might choose a different lens for the dominant second eye. Given that the lens pairs in this study were selected by the surgeon as the best combination for each patient, it is also possible, of course, that patients in each group were relatively equally satisfied because the lens combination was appropriately tailored to each group’s varying needs and expectations.

Ultimately, there is no substitute for talking to the patients about their visual demands and expectations, understanding the pros and cons of each presbyopia-correcting IOL available to us, and identifying the best match between the two.

Dr Teenan is UK and Ireland Medical Director for Optical Express.

Articles

Presbyopic outcomes at Optical Express: A retrospective analysis

	Take-home: Patient satisfaction is high following implant of the Symfony IOL, which is designed with an elongated focal zone in an attempt to minimise visual compromises and avoid visual dysphotopsias.

	A primary unintended consequence of lens platforms offering vision correction in multiple vision zones is the incidence of visual dysphotopsias. Glare and haloes after implantation of a multifocal IOL are highly variable. In controlled clinical trials with the Tecnis IOLs (Abbott), the incidence of moderate haloes was 6% and severe halo occurred in 5%.

 In studies of the AcrySof multifocal lens (Alcon), 2.7% reported severe glare and 11% severe haloes.

	Fundamentally, design considerations may explain these differences. However, additional factors such as residual refractive error, wavefront anomalies, IOL decentring, posterior capsular opacification and dry eye disease may also induce postoperative photic phenomena.

 Thus, although lens design is integral to reducing the potential for postoperative visual disturbances, the surgeon must still pay careful attention to optimising the ocular surface and performing meticulous surgery.

	It is hoped that a new-design lens will lower incidence of glare and halo via elongation of the focal zone. The TECNIS Symfony IOL (Abbott) may also provide improvements in chromatic aberration, providing patients with sharper vision. A recently completed patient satisfaction survey demonstrated that these design considerations translate to improved performance.

The role of competing vision zones in visual disturbances

	Traditional multifocal lenses are constructed using diffractive optics, which split light into multiple zones for vision at near, intermediate and distance. The lens options on the market employ different design considerations to provide vision at different distances without compromising quality of vision.

	The AcrySof IOL utilises apodised optics to spread light distribution across the surface of the IOL based on the size of the pupil and vision demand. That is, more light is theoretically available in the near-distance zone when the focus is near. These lenses are available in two models, +2.5 and +3.0, with the former intended to provide greater distance vision and the latter intended to provide equal vision across all three distances. However, an inescapable fact of such a design is that light diffracted through multiple vision zones at the optical surface results in competing images on the retina, which is the basis for visual phenomena such as halo and glare.

	The Tecnis family of IOLs employ a slightly different mechanism, with a wavefront-designed aspheric surface and a posterior diffractive surface. Three different lens options are offered to permit customisation of the lens to a patient’s individual vision needs: the +4.0 model has a theoretical reading distance of 33 cm, the +3.25 lens a theoretical reading distance of 42 cm and the +2.75 model a theoretical reading distance of 50 cm. The aspheric surface is intended to reduce contrast sensitivity, and may affect the path of light transmitted through the posterior diffractive zone. However, again, a design fundamental of the Tecnis family is that the diffractive optics split light to different foci, which has the potential to cause dysphotopsias.

	Another lens option corrects vision across the multiple viewing ranges via pseudoaccommodation (Crystalens; Bausch & Lomb). Postmarketing evidence suggests that, although these lenses provide good distance vision, patients may require glasses for near demands, and so the lens may not supply the full range of vision of other IOL technologies.

A new design in IOLs: extended range of vision

	The Tecnis Symfony IOL is designed with a diffractive echelete that creates a novel diffraction pattern to elongate the depth of focus (Figure 1). Even though light comes from distinct points, the elongated focus brings the light to a similar point on the retina. Correspondingly, this increased depth of focus relative to monofocal and other multifocal platforms creates a mechanism to ensure less defocus in the visual plane – in other words, less light that is out of focus. Because haloes and glare result from defocused images in the viewing plane along the z-axis, the Symfony’s elongated depth of focus yields the ideal solution to reduce dysphotopsias.

	Such an effect is demonstrated in defocus curves demonstrating 20/20 or better mean visual acuity from distance to 1.5 D of defocus, 20/40 or better mean visual acuity from distance to 2.5 D of defocus and a 1.0 D increase in depth of focus throughout the defocus curve (Figure 2).

	Furthermore, the Symfony is constructed with achromatic technology intended to reduce wavelength-dependent defocus. Chromatic aberration results from certain wavelengths of light stopping short of the point of focus (the macula), resulting in blur and reductions in contrast. Studies suggest that the average eye has around 2.0 D of chromatic aberration between 400 and 700 nm and 0.8 D between 500 and 640 nm.

 The achromatic technology in the Symfony platform yields sharper focus, in effect bringing the focal point of each wavelength closer to the macula, thereby resulting in sharper vision less given to chromatic variance. Because it is coupled with correction of spherical aberration, the resulting vision does not sacrifice depth of focus (Figure 3).

	I recently completed a patient satisfaction survey in my clinic, assessing visual outcomes after implantation with the Tecnis Symfony IOL in a population of 160 eyes of 80 patients undergoing refractive lens exchange. This was a retrospective review with the primary objectives of measuring uncorrected distance visual acuity (UCDVA), uncorrected near visual acuity (UCNVA), patient satisfaction and complications.

	One month after surgery, UCDVA was 20/32 or better in 93% of patients while UCNVA was 20/50 in 88%. In the questionnaire, 83% of patients reported being satisfied or very satisfied and 90% of patients said they would recommend the procedure. Severe difficulty with glare, haloes and ghosting was reported by only 7%, 6% and 1% of patients, respectively. Little or no difficulty with driving at night was reported by 72% of patients reported. There were no reported intra- or postoperative complications (Figure 4).

	Many variables affect presbyopic patients’ ability to see at multiple distances after implantation of a phakic IOL. Thus, even with new designs on the market, such as the Symfony, it remains critically important to understand the individual vision demands and desires of the patient, as well as what he or she is willing to compromise to achieve the desired refractive outcome. The level of compromise the patient is willing to accept will direct the lens choice. If the patient wants good reading, perhaps a higher add multifocal lens would be appropriate, assuming there is an understanding that there may be some issues with quality of vision. In contrast, a patient who drives a lot might be happier with a low add multifocal, with the caveat that some distance acuity may be lost.

	Ultimately, then, what the Symfony technology offers by way of an extended range of focus is another lens option to match to patients’ specific needs. There is less chance of a visual compromise at any given distance, and an improved chance that visual dysphotopsias can be avoided. Lastly, studies demonstrate that the proprietary features of the Symfony allow it to transmit light with achromatic correction in order to deliver the best overall quality of vision. Studies demonstrating that Symfony offers optimal modular translation function are not simply data emanating from the laboratory: the conclusions are reinforced by surveys demonstrating that patients are able to perceive the differences in quality of vision at all distances, and, in turn, are extremely satisfied with the vision the lens provides.

	1. Tecnis Multifocal 1-Piece IOL, Model ZMB00 [package insert]. Santa Ana, CA: Abbott Medical Optics, Inc.; 2009.

	2. AcrySof IQ Restor [package insert]. Fort Worth, TX: Alcon Laboratories, Inc.; 2008.

	4. 166 Data on File_Extended Range of Vision IOL 3-Month Study Results (NZ).

Patient satisfaction is high following implant of the Symfony IOL, which is designed with an elongated focal zone in an attempt to minimise visual compromises and avoid visual dysphotopsias.

Author | David Teenan FRCS(Ed), FRCOphth

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Presbyopic outcomes at Optical Express: A retrospective analysis

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