The Ins and Outs of Trifocal Lenses
As clinicians, we constantly strive to do the best for our patients. Innovations in de- sign and technology afford us the confidence to offer premium vision correction to many of them. Unique trifocal and extended depth of focus (EDOF) lenses have given us unrivalled visual excellence, but careful patient selection and education is vital for success.
Ideally we would offer these lenses to every patient seeking spectacle independence and bin- ocular distance vision, but there are some limiting factors, primarily co-existing ocular pathology: Fuch’s dystrophy, poorly managed dry eye, macular degeneration, weak zonules, advanced glaucoma, amblyopia, previous radial keratotomy, and unreactive or tonic pupils. Any ocular pathology that results in light scatter will degrade the quality of vision produced by a trifocal lens. Dr. Thomas Neuhann, Laser Eye Centre Munich, Germany, advises caution using these lenses in a low myope. “Their lifelong excellent uncorrected near vision and, consequently, expectation, is a great danger for disappointment with the near vision with such lenses,” he said.1
Patient education and personality are other important factors to consider. Expectations must be carefully managed and compromises highlighted. Patient occupation and the visual needs required should also be carefully considered. Realistic expectations from an educated patient will ensure success. More chair time preoperatively results in less chair time (and cost) postoperatively.
The early multifocal lenses were bifocal in design with two focal points: distance and near. Increased demand for computer and mobile device use means an intermediate focal point is now import- ant for many patients. Dr. A. John Kanellopoulos, Clinical Professor of Ophthalmology NYU Med School, New York, noted, “This also happens to be the range of vision essential for activities such as cooking, gardening, and viewing the speedometer in a car.”2 Traditionally, patients older than 60 years had less demand for intermediate vision but this is no longer the case. We have tended to prescribe the bifocal lens as a blended vision solution in an attempt to achieve all three working distances. Dr. Vance Thompson, Vance Thompson Vision, Sioux Falls, South Dakota, explained, “We will either implant an EDOF intraocular lens (IOL) or a lower add bifocal in the dominant eye, and we will implant a higher add bifocal in the non-dominant eye in an attempt to get all three distances.”1 With the new trifocal model, the same lens can be placed in each eye targeting emmetropia to obtain vision at all three distances and enhance binocularity. Hayashi et al. found emmetropia should always be the target when using a trifocal in each eye, but slight myopia enhances near vision and so is a preferable refractive surprise when compared to slight hyperopia, which degrades distance and near vision.3
The New Generation of Trifocals
The most commonly used new generation trifocal models are FineVision (PhysIOL, Liege, Belgium, 2010), AT LISA (Carl Zeiss Meditec, Jena, Germany, 2012) and Acrysof IQ PanOptix (Alcon, Fort Worth, Texas, FDA approved 2019).2 The FDA-approved EDOF lens available is the Symfony (Abbot Medical Optics, Abbott Park, Illinois, FDA approved 2016). The LENTIS Com- fort (Oculentis GmbH, Berlin, Germany, 2012) is another EDOF IOL lens.
The technology in the new trifocal model works in two ways: to extend the range of vision by elongating the focus of the lens (refractive) and to reduce the chromatic aberration (diffractive). The refractive technology is already used in aspherical monofocal lenses; the unique diffractive design is a feature of the new multifocal IOL model.2
FineVision is the first trifocal to come on the market with one diffractive zone for distance and near, and one for distance and intermediate focus that overlap.2 It is now made in a hydrophobic material to minimise capsular opacification. The light distribution is dependent on pupil size, with the highest power for reading at the center of the lens as the pupil naturally constricts at near.
AT LISA uses a hydrophilic aspheric de- sign with a hydrophobic surface that uses a refractive-diffractive pattern with a trifocal function designed to enhance intermediate vision over the central optic.2,4 The patented smooth rotationally symmetric lens surface design reduces dysphotopsia effects. It uses a diffractive pattern with a trifocal design over
4.3 mm, providing a near addition of +3.33 D and an intermediate addition of +1.66 D, making it independent of pupil diameter.4
The PanOptix rotationally symmetric hydro- phobic lens is described as a quadrifocal IOL that acts as a trifocal. There are three step heights that result in three focal points (near 40 cm, intermediate 60 cm, and extended intermediate 120 cm) in addition to distance. Using the diffractive principal, the extended intermediate focal point is refracted to the distance focal point to increase performance; there is less dependence on pupil size.2,5 This results in only three foci: distance, intermediate at 60 cm, and near at 40 cm.
The Symfony EDOF is a hydrophobic IOL with a biconvex wavefront-designed anterior aspheric surface and posterior achromatic diffractive surface. It is a rotationally symmetric model.6
LENTIS Comfort is a sectorial aspherical asymmetric refractive lens that creates several juxtaposed concentric optical zones of different optical power. Having the surface-embedded segment means it is independent of pupil size. Light hitting the transition area is deflected away from the optical axis, resulting in improvement in contrast sensitivity and decreased glare and halo.7
The Toric Model
All of these lenses include a toric model designed to mitigate the effects of astigmatism, increasing the number of patients who can receive premium IOLs.2,10 Of course this means more variables are involved, with axis orientation and cylinder magnitude that make preop-erative assessments even more critical. Mojzis et al. determined the AT LISA tritoric provided high levels of unaided visual acuity, spectacle independence, and quality of life with minimal higher order aberrations and good levels of contrast sensitivity.8 Refractive error with a multifocal lens will result in more significant visual degradation compared to a monofocal lens. With an emmetropic target, a toric should always be calculated and used, if available.
Lenses using the refractive principle of focus (LENTIS Comfort) tend to have increased contrast sensitivity and so are the lenses of choice for patients who frequently drive at night or work in low environmental light conditions.2 They are also advised for those of advanced age with low contrast sensitivity. The diffractive models are best suited to those who are working in an office environment during the day and want good general vision at the three distances.2,10 However, clinical data are continuing to prove that the trifocal lens does not compromise on contrast sensitivity or increase optical phenomena when compared with EDOF lenses.9,10
Recent clinical results from Mencucci et al. compared two trifocals, PanOptix and AT LISA, with the Symfony EDOF.4 All three lenses provided good visual outcome, patient satisfaction, and spectacle independence, but the trifocal designs provided better near acuity with no compromise on contrast sensitivity or optical phenomena.4 A multicenter clinical trial headed by Ruth Lapid-Gortzak, MD, PhD, Department of Ophthalmology, Academic Medical Center, University of Amsterdam, the Netherlands, com- pared the PanOptix and AT LISA lenses. Results showed the PanOptix group had superior visual performance at intermediate and near distances while maintaining good distance vision; contrast sensitivity was similar in both groups.11
With positive clinical results emerging, trifocal and EDOF lenses should become our lenses of choice for patients requesting spectacle independence and binocularity.12
1. Stephenson M. Device focus: Trifocal IOLs provide near, intermediate, and distance vision. EyeWorld. January 2019.
2. Stuart A. The lowdown on high-tech IOLS. EyeNet Magazine. October 2017.
3. Hyashi K, Sato T, Igarashi C, Yoshida M. Effect of spherical equivalent error on visual acuity at various distances in eyes with a trifocal intraocular lens. J Refract Surg. 2019; 25(5):274-279. doi: 10.3928/1081597X-20190404-01.
4. Mencucci R, Favuzza E, Caporossi O, Savastano A, Rizzo S. Comparative analysis of visual outcomes, reading skills, contrast sensitivity, and patient satisfaction with two models of trifocal diffractive intraocular lenses and an extended range of vision intraocular lens. Graefes Arch Clin Exp Ophthalmol. 2018;256(10):1913-1922. doi: 10.1007/s00417- 018-4052-3.
5. Alcon Consultancy Panel. PanOptixTM enlightening conversa- tion: Highlights from the Prague 2016 Alcon Multifocal IOL User Meeting. https://theophthalmologist.com/fileadmin/top/ issues/0816/Alcon.pdf. 2016.
6. Cochener B. Clinical outcomes of a new extended range of vision intraocular lens: International Multicenter Concerto Study. J Cataract Refract Surg. 2016;42:1268–1275. doi: 10.1016/j.jcrs.2016.06.033.
7. Experience comfort without compromise [supplement]. Cataract & Refractive Surgery Today. July/August 2016.
8. Mojzis P, Majerova K, Plaza-Puche AB, Hrckova L, Alio JL. Visual outcomes of a new toric trifocal diffractive intraocular lens. J Cataract Refract Surg. 2015;41(12):2695-706. doi: 10.1016/j.jcrs.2015.07.033.
9. Weeber HA, Meijer ST, Piers PA. Extending the range of vi- sion using diffractive intraocular lens technology. J Cataract Refract Surg. 2015;41. doi: 10.1016/j.jcrs.2015.07.034.
10. Hida TW, Cortez Vilar CM, Medeiros AL, et al. Multicenter visual outcomes comparison of 2 trifocal presbyopia-correcting IOLS: Six-month results. Presented at: 2018 ASCRS-ASOA Annual Meeting; April, 2018; Washing- ton, DC.
11. Lapid-Gortzak R, Duch F, Elies D, Guarro M, Martinex A. Multicenter visual outcomes comparison of two trifocal presbyopia correcting iols–6 months post-op results. Paper presented at: 2018 World Ophthalmology Congress; June 2018; Barcelona.
12. Wilkins MR, Allan BD, Rubin GS, et al. Randomized trial of multifocal intraocular lenses versus monovision after bilateral cataract surgery. Ophthalmol. 2013;120(12):2449-2455. doi: 10.1016/j.ophtha.2013.07.048.