Trifocal Intraocular Lenses
The first trifocal IOL was recently approved by the FDA for use in the United States. This article will review the optics and use of trifocal intraocular lenses (IOLs), focusing on the PanOptix IOL from Alcon, and comparing it to the currently approved bifocal and extended depth of focus lenses in the US. It will also be compared to other trifocal IOLs available internationally.
The PanOptix trifocal IOL is 13 mm in diameter with a central optic of 6 mm. The 6mm optical zone is composed of a central 4.5 mm diffractive area with 15 diffractive zones and an outer refractive rim. The relatively smaller central diffractive area (4.5mm vs 6mm in other Trifocals and EDOF lenses) and greater light utilization, with 25% of light being distributed for near, 25% for intermediate and 50% for distance, is meant to create good visual acuity even with dilated pupils. The anterior surface is aspheric with negative spherical aberration (-0.10 micrometers) to compensate for the average spherical aberration of the human cornea .
Technically, the PanOptix is a quadrafocal lens in that it creates a fourth focal point at 1.20 m. This fourth focal point is not accessible to the patient, instead the light is diffracted towards distance with a goal of increasing light efficiency and creating a more natural transition between near, intermediate and distance vision  . The focal points are approximately located at 40 cm for near, 60 cm for intermediate, and infinity for distance. The focal point of 60 cm sets Panoptix apart from other multifocal lenses which have their intermediate distance focal point at 80 cm.
The defocus curves for the PanOptix have been consistent across studies showing good VA over a range of diopters (+0.50 D to -3.0D) with two peaks in the defocus curves approximately at 0.00D and -2.00D .
MTF performance, Badal Images
Optical bench testing of the PanOptix was done using the multifocal ReSTOR +3.0D lens as a comparison. MTF measurements were taken with an aperture of 3 mm at spatial frequencies of 100 and 50 lines pairs per millimeters (lp/mm). ReSTOR had better distance and near focus values while intermediate values were greater with the PanOptix. The following values for PanOptix were recorded:
- Distance focus MTF at 100 and 50 lp/mm was 30.9% and 40.2% respectively
- Near focus MTF at 100 and 50 lp/mm was 15.3% and 18.1% respectively
- Intermediate focus MTF at 100 and 50 lp/mm was 13.3% and 15.3% respectively
The badal images revealed that at 3 mm aperture (pupil size), the PanOptix had improved intermediate vision performance (at 60 and 80 cm distance) of 3 lines when compared to the ReSTOR multifocal lens. Distance and near badal images were similar for the PanOptix and ReSTOR. Of note, these results were similar at 4.5 mm pupil size, suggesting that the optical design of PanOptix which allows for good visual acuity at larger pupil size functions as intended
Halo propensity was also studied in the aforementioned optical bench performance study comparing the PanOptix to the multifocal ReSTOR +3.0 D IOL by Lee et al. They measured photic phenomena such as halos in the form of a simulated car headlight. The halos diminished at a shorter distance from the central light in the ReSTOR multifocal compared to the PanOptix and the halos were more visually distinct in the PanOptix (see Figure 3 from Lee et al). This was attributed to the fact that the PanOptix lens is non-apodized while the ReSTOR multifocal is apodized.
Clinical Outcomes of Trifocal Implantation
Clinical outcomes across studies have been consistent, showing good visual acuities at Distance intermediate and near with the most impressive results at the intermediate distances, 80 and 60 cm. The following are results from two non-comparative studies with relatively larger sample sizes:
In a prospective study (n=27), at 3 months post op, Kohnen et al showed:
- Mean binocular UDVA of 0.00±0.094 logMAR
- Mean binocular UIVA of 0.09±0.107 logMAR at 80cm and 0.00±0.111 logMAR at 60cm
- Mean binocular UNVA of 0.01±0.087 logMAR
In a retrospective review of 33 patients by Lawless et al showed:
- Mean UDVA of 0.01±0.10 logMAR
- Mean UIVA of 0.30±0.14 logMAR with 88.9% achieving 0.20 logMAR or better binocularly
- Mean Binocular UNVA of 0.11±0.04 logMAR
Reading speed with the PanOptix has been found to be similar to the reading speeds recorded with other Trifocals available in Europe and EDOF lenses, and those reading speeds are considered above the level proposed as fluent reading. Mencucci et al reported that in 40 eyes, maximum reading speed, as defined by words per minute=[60x (10-errors0]/time in seconds), as 176.28 under photopic conditions and 161.27 under mesopic conditions. The reading acuity logMAR (defined as the size of the last correctly read sentence) was 0.19 in photopic conditions and 0.31 in mesopic conditions.
Different tests used to measure contrast sensitivity across studies makes it hard to directly compare studies but regardless of test used, the PanOptix has performed comparably to other multifocal lenses and extended depth of focus lenses in regards to contrast sensitivity in photopic and mesopic conditions. Patients CS’s have been within the expected range for their age group.
In a prospective study (n=27), at 3 months post op, Kohnen et al showed:
- CS of 1.55±0.35 logCS Weber under Photopic conditions
- CS of 0.91±0.26 logCS Weber under Mesopic conditions
- CS of 0.86±0.26 logCS Weber under Mesopic with glare conditions
Reports of spectacle independence have varied slightly across studies. Sudhir et al reviewed current clinical literature with respect to the PanOptix and found that among 6 clinical studies, >85% of patients achieved complete spectacle independence for all distances.
Visual phenomenon: Glare, Halos, Night Vision difficulties
Similar to other trifocal lenses and the EDOF lens, the most common complaint patients with the PanOptix have is difficulty with halos, glare and night vision. These complaints vary widely from study to study (1% in Cochener et al to 93% in Kohenen et al) but generally patients have reported that they have no impact on their daily lives and that their complaints decrease over time. In the study where 93% of the 27 patients reported visual pheonomenon, 89% reported halos and 11% reported glare.
Tolerance for ametropia (residual astigmatism or near/far sightedness)
Data for PanOptix shows that it is comparable to other Trifocal lenses in regards to residual astigmatism or near/far sightedness. In a study involving 20 patients with the PanOptix lens, 76% of the eyes were within 0.50D for spherical equivalent and 89% of the eyes had less than 1.00D of residual astigmatism. Another study involving 20 patients reported that pre-operative spherical equivalent in the PanOptix group as -0.21±0.67 D compared to -0.20±0.56 D at 3 month post op measurements.
Comparison between Trifocal vs EDOF (Symfony)
Head to Head Trials
Monaco et al completed a randomized controlled trial comparing the PanOptix (n=20) with the Symfony lens (n=20) and a monofocal lens (n=20).
- The primary outcome measured was distance-corrected near visual acuity which was significantly better with the PanOptix group with a logMAR of 0.01± 0.04 compared to 0.07± 0.07 in the Symfony group (p=0.005).
- Secondary outcome measurements of UDVA, CDVA and DCIVA showed no statistically significant difference between the PanOptix and Symfony lens.
- Defocus curves showed statistically significantly better VA with the PanOptix than the Symfony for vergence of -1.5 D, and from -2.5 to -4.0 D.
- Dysphotopsia complaints did not differ statistically between PanOptix and Symfony. 3 PanOptix patients (15%) complained of halos vs 5 Symfony patients (25%).
Cochener et al completed a randomized controlled trial comparing PanOptix (n=20) and the Symfony lens (n=20) in addition to another Trifocal lens, FineVision (n=20).
- There was no statistically significant difference in UDVA or UIVA between groups.
- Near vision was better in the PanOptix group compared to the Symfony group with 81.5% of PanOptix patients achieving a monocular VA of J2 (>20/32) vs 52.5% of Symfony patients and 100% of PanOptix patients achieving binocular VA of J2 (>20/32) vs 70% of Symfony patients.
- Contrast sensitivity was similar among all groups studied with a decrease in CS without correction versus with correction, and a decrease under mesopic conditions.
Comparison between Trifocal vs Bifocal
Studies comparing specifically the PanOptix trifocal lenses with bifocal lenses are limited, though there exist many studies comparing other trifocal lenses with bifocal lenses.
Vilar et al completed a prospective, nonrandomized comparative study using PanOptix trifocal lenses vs a blended bifocal implant (a different bifocal in each eye). In regards to Visual acuity the following post operative measurements were obtained:
- UDVA 0.01±0.04 in PanOptix group vs 0.08±0.05 in the bifocal group (p=<0.01)
- UIVA 0.14±0.05 in PanOptix group vs 0.22±0.06 in the bifocal group (p=<0.01)
- UNVA -0.03±0.04 in PanOptix group vs 0.07±0.03 in the bifocal group (p=<0.01)
- The trifocal lens had statistically significant better contrast sensitivity at 6, 12, and 18 cycles/degree without glare and 18 cycles/degree with glare.
- Under mesopic conditions with glare, the bifocal blended group had better contrast senstivity at 3, 6 and 12 cycles/degree while the trifocal did better at 1.5 cycles/degree.
- Defocus curves showed that PanOptx trifcoal had statistically significant better VA from -2.00D to plano and at -3.50.
De Medeiros et al compared the VA in patients with PanOptix Trifocal (10 patients, 20 eyes) vs a blended group (10 patients, 20 eyes) where one eye had a Symfony EDOF lens and the other a bifocal Tecnis ZMB00.
- UDVA for blended was -0.096 logMAR vs 0.010 logMAR in the trifocal group (p=0.0295)
- CDVA was -0.16 logMAR in blended vs -0.07 logMAR in trifocal group (p=0.01)
- UNVA was 0.11 logMAR in blended vs -0.03 logMAR in trifocal group (p=0.01)
- UIVA was 0.20 logMAR in blended vs 0.14 logMAR in trifocal group (p=0.01)
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- Kohnen T. First implantation of a diffractive quadrafocal (trifocal) intraocular lens. J Cataract Refract Surg 2015; 41:2330–2332.
- Sudhir, Rachapalle Reddi et al. “AcrySof IQ PanOptix Intraocular Lens Versus Extended Depth of Focus Intraocular Lens and Trifocal Intraocular Lens: A Clinical Overview.” Asia-Pacific journal of ophthalmology (Philadelphia, Pa.) vol. 8,4 (2019): 335-349.doi:10.1097/APO.0000000000000253
- Kohnen, Thomas, et al. "Visual performance of a quadrifocal (trifocal) intraocular lens following removal of the crystalline lens." American journal of ophthalmology 184 (2017): 52-62.
- Lee, Shinwook et al. “Optical bench performance of a novel trifocal intraocular lens compared with a multifocal intraocular lens.” Clinical ophthalmology (Auckland, N.Z.) vol. 10 1031-8. 2 Jun. 2016, doi:10.2147/OPTH.S106646
- Lawless, Michael, et al. "Visual and refractive outcomes following implantation of a new trifocal intraocular lens." Eye and Vision 4.1 (2017): 10.
- Mencucci, Rita, et al. "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." Graefe's Archive for Clinical and Experimental Ophthalmology 256.10 (2018): 1913-1922.
- Cochener, Beatrice, et al. "A comparative evaluation of a new generation of diffractive trifocal and extended depth of focus intraocular lenses." Journal of Refractive Surgery 34.8 (2018): 507-514.
- Monaco, Gaspare, et al. "Visual performance after bilateral implantation of 2 new presbyopia-correcting intraocular lenses: Trifocal versus extended range of vision." Journal of Cataract & Refractive Surgery 43.6 (2017): 737-747.
- Vilar, César, et al. "Comparison between bilateral implantation of a trifocal intraocular lens and blended implantation of two bifocal intraocular lenses." Clinical ophthalmology (Auckland, NZ) 11 (2017): 1393
- de Medeiros, André Lins, et al. "Comparison of visual outcomes after bilateral implantation of a diffractive trifocal intraocular lens and blended implantation of an extended depth of focus intraocular lens with a diffractive bifocal intraocular lens." Clinical ophthalmology (Auckland, NZ) 11 (2017): 1911