Since IOLs were approved for widespread use some 40 years ago, implant technology has been the focus of intense R&D driven by the needs and preferences of patients and surgeons. A variety of novel lens designs can correct for presbyopia, astigmatism, and myopia at the time of cataract surgery. Advanced-technology or “premium” IOLs include new shapes built from new materials.

The following is a brief review of the premium IOL landscape.

Multifocals

Multiple zones of lens power produce more than one focal point, enhancing near and far vision — like multifocal contact lenses. These lenses are either bifocal, trifocal, or extended depth of focus (EDOF). Multifocal IOLs may lack acuity in the middle range, however, and new lenses look to improve on this.

Multifocal IOLs employ refractive or diffractive principles. Refractive multifocal IOLs create multiple focal points for viewing at all distances. Diffractive implants provide two or three distinct images for near, intermediate, and far. Each has its pros and cons, and a careful preoperative evaluation is necessary to find the most appropriate solution for each patient.

If multifocal IOL principles depend on the size of the pupil, patients may experience problems like glare and halos. Diffractive multifocal IOLs allow for more stray light than refractive implants, and studies have revealed a significantly higher rate of visual symptoms in patients with multifocal vs. monofocal IOLs.¹ Still, patients tend to be highly satisfied with multifocal IOL lenses.¹

Here is a summary of the available multifocal lenses:

• Diffractive bifocals. Diffractive bifocal IOLs produce near and far images distinctly. The first, AcrySof Restor (Alcon), received FDA approval in 2005. It relies on apodization, in which the center of the disc is used for near vision. It is surrounded by concentric rings of decreasing height for distance. The Tecnis Multifocal IOL (Johnson & Johnson Vision) has an aspheric anterior surface with diffractive rings on the posterior surface to focus light no matter the pupil size. These may fall short in the intermediate range compared with other designs.¹
• Diffractive trifocals. Wide, flat defocus curves help trifocal IOLs produce fewer visual side effects, improving vision. Outside the United States, the trifocal IOL is popular for presbyopia correction because it provides a third focus point that improves intermediate vision. In the United States, Alcon’s PanOptix is the only trifocal available. More than 99% of patients who received the lens in clinical trials said they would choose it again.²
• EDOF. These lenses provide a wider range of vision without sacrificing distance visual acuity. They seek to eliminate halos and other unwanted optical side effects but may decrease visual sharpness and contrast. Johnson & Johnson Vision’s Symfony EDOF IOL has an echelette design to reduce chromatic and negative spherical aberration. It improves intermediate vision compared to monofocal controls, and patients report fewer aberrations and enhanced contrast sensitivity.^3,4 EDOF implants can also be combined with other types of IOL technologies to enhance their strong points.

Accommodative

Accommodation is the change in the refractive power of the eye when the image of a near object is brought into focus on the retina. Because it can change its shape in response to eye muscle movements, an accommodative lens can change its power.

The Crystalens IOL (Bausch + Lomb) is the only FDA-approved accommodative IOL. It simulates the eye’s natural accommodative process using its flexible haptics. When placed in the capsular bag, it changes power as the ciliary muscle moves. The Crystalens offers good distance vision and reduced visual disturbances compared to multifocal IOLs.⁵

Toric (monofocal)

Toric lenses decrease astigmatism after cataract surgery. To offset a patient’s astigmatism caused by the eye’s asymmetry, torics have different lens medians with different powers. Surgeons must accurately rotate the lens in the eye getting the proper alignment. Key to success is the preoperative workup, which includes accurate measurements, precise power calculation, and optical lens choice. The previously mentioned manufacturers offer toric versions of their presbyopia-correcting technology platforms.

Johnson & Johnson Vision released its updated Tecnis Toric II IOL platform that touts new haptics with increased friction that the company says help it to stay put.⁶ Alcon’s AcrySof IQ Toric IOL claims exceptional rotational stability in a wide range of powers.⁷ Bausch + Lomb’s enVista toric delivers stability and visual clarity and boasts a glistening-free material.^8,9

Adjustable lens (monofocal)

The FDA-approved Light Adjustable Lens and Light Delivery Device (both by RxSight) is a truly disruptive IOL technology. The three-piece silicone implant contains unpolymerized macromers within the optic substance. Surgeons lock in the appropriate power adjustment by irradiating the lens.¹⁰ In the clinical trial, 92% of patients were within 0.50 D of goal with two light adjustments.¹¹

Conclusion

With all of this new technology comes increased expectations. In 2020, surgeons and patients want a future free of presbyopia, astigmatism and corrective spectacles or contact lenses after cataract surgery. Premium IOL types and the principles on which they work are attempting to make those expectations a reality.

Moving forward, physicians are hopeful new implants in the pipeline will help increase patient satisfaction and improve on earlier shortcomings. For example, future IOL designs include models with surfaces that can change shape or otherwise dynamically provide the correct refractive power for lighting conditions. OP

REFERENCES

1. Zvorničanin J, Zvorničanin E. Premium intraocular lenses: The past, present and future. J Curr Ophthalmol. 2018;30(4):287-296.
2. Alcon Introduces AcrySof IQ PanOptix Trifocal IOL in the U.S., the First and Only FDA-Approved Trifocal Lens. Aug. 27, 2019. www.alcon.com/media-release/alcon-introduces-acrysof-iq-panoptix-trifocal-iol-us-first-and-only-fda-approved . Accessed Dec. 5, 2019.
3. TECNIS Symfony Extended Range of Vision IOL Directions for Use. https://www.jnjvisionpro.com/sites/us/files/public/z311215_01.pdf . Accessed February 17, 2020.
4. DOF2015CT0020 Symfony MTF versus competition. https://www.escrs.org/vienna2018/programme/poster-village-details.asp?id=31778 . Accessed Dec. 10, 2019.
5. Doane JF. Accommodating intraocular lenses. Curr Opin Ophthalmol. 2004 Feb;15(1):16-21.
6. Johnson & Johnson Vision Introduces TECNIS Toric II 1-Piece IOL as New Monofocal Option for Cataract Patients with Astigmatism; Launching Multi-Center, Post-Market Clinical Trials Across U.S. 2019. www.prnewswire.com/news-releases/johnson--johnson-vision-introduces-tecnis-toric-ii-1-piece-iol-as-new-monofocal-option-for-cataract-patients-with-astigmatism-launching-multi-center-post-market-clinical-trials-across-us-300968149.html . Accessed Feb. 17, 2020.
7. Alcon. Astigmatism Correction with AcrySof IQ Toric IOLs [https://www.myalcon.com/professional/cataract-surgery/intraocular-lens/acrysof-iq-toric-iol ]. Accessed Feb. 17, 2020.
8. Data on file. Bausch + Lomb Inc.
9. Bausch + Lomb enVista Hydrophobic Acrylic Intraocular Lens Directions for Use. www.bausch.com/Portals/77/-/m/BL/United%20States/Files/Downloads/ECP/Surgical/enVista/enVista_eDFU.pdf?ver=2017-08-09-141858-330 ]. Accessed Feb. 17, 2020.
10. Werner L, Chang W, Haymore J, et al. Retinal safety of the irradiation delivered to light-adjustable intraocular lenses evaluated in a rabbit model. J Cataract Refract Surg. 2010;36(8):1392-1397.
11. Schojai M, Schultz T, Schulze K, Hengerer FH, Dick HB. Long-term follow-up and clinical evaluation of the light-adjustable intraocular lens implanted after cataract removal: 7-year results. J Cataract Refract Surg. 2020;46(1):8-13.