New Presbyopia Options
EDOFs looking good, for now
Affecting about 1.5 billion people worldwide, presbyopia is among the most prevalent visual needs. As populations age, those numbers are rising, as is the proportion of people seeking spectacle-free solutions, according to presenters at the 40th Congress of the ESCRS in Milan.
Indeed, industry sources said at the inaugural ESCRS iNovation programme that presbyopia-correcting IOLs (PCIOLs) are picking up market share. And while 55% of ESCRS members surveyed for the programme implant PCIOLs—in less than 5% of eligible patients—65% see their usage increasing in the next year.
Newer monofocal-plus and extended depth of focus (EDOF) IOLs are driving much of the interest, said Lucio Buratto MD, who chaired a symposium on presbyopia correction at the Congress. These lenses reduce optical disturbances such as glare, halos, and starbursts that many users found intolerable in earlier multifocal lenses—though newer multifocal and hybrid designs also reduce these phenomena.
Presbyopia-correcting corneal laser surgery is an option for younger patients, as is a new presbyopia-correcting phakic IOL. Monovision, either alone or in combination with PCIOLs, is another option, as is optimising spherical aberration (SA) in monofocal lenses for individual patient pupil size and corneal SA.
But a solution that reliably duplicates the long-lasting accommodative function of the natural crystalline lens remains in the future, said George Beiko MD. In the meantime, available static solutions involve trade-offs. Matching the strengths and weaknesses of each to specific patient needs and preferences is still critical, the presenters emphasised.
Presbyopia LASIK imparts multifocality to the cornea, said Thomas Kohnen MD, PhD. It can be performed with a peripheral zone for near vision and a central zone for distance, but a centre near add ablates less tissue, making it the preferred method. Ablation profiles can vary to increase the depth of field, which can be used to create blended vision by targeting the distance eye for plano and the non-dominant eye for -1.25 D to -1.5 D. The two extended in-focus zones overlap, potentially improving binocular summation while providing approximately 3.0 D of pseudoaccommodation. However, he noted a trade-off between increased depth of field and reduced quality of vision.
In a study Dr Kohnen conducted using the Schwind PresbyMAX system, 15 patients were treated with a micromonovision approach, and 15 with a hybrid approach with less depth of focus in the distance-corrected eye. Overall, there was a slight loss of corrected distance visual acuity, from -0.16 to -0.06 logMAR, and a big gain in uncorrected near vision, from 0.48 to 0.05 logMAR. There were no significant differences in distance and intermediate vision, but the micromonovision group had better near vision at 0.09 versus 0.30 logMAR. Overall, only 10% used spectacles for reading, and 82% would undergo the same procedure again.
However, presbyopic LASIK outcomes can be problematic. In a 2017 review, most authors reported a significant risk of loss of two or more lines of distance visual acuity, which can result from dry eye or induction of higher order aberrations.i “Corneal multifocality is a developing area. It can restore near vision, but it comes with risks,” Dr Kohnen said.
This is a major reason why Dr Buratto said he no longer does presbyopic LASIK. In addition, it is a temporary solution patients in their 40s may outgrow as presbyopia progresses, and it limits later options for presbyopic IOLs, he noted. The new presbyopiacorrecting Staar Surgical Visian® ICL™, which is reversible, may be an option for younger presbyopic patients.
MULTIFOCAL AND EDOF IOLs
Presbyopia-correcting IOLs range from enhanced monofocal to EDOF to multifocal lenses, and these address the problem in a variety of ways involving different trade-offs, said Rudy MMA Nuijts MD, PhD of Maastricht University, the Netherlands.
For example, the Johnson & Johnson Tecnis Eyehance™ is a refractive lens that continuously increases refractive power from the periphery to the centre, delivering distance visual acuity and a dysphotopsia profile similar to monofocal IOLs while improving intermediate vision. In a comparative study against a monofocal lens and the first-generation EDOF Symfony, the Eyehance delivered similar defocus at -1.0 D and similar binocular intermediate vision with the Eyehance with better results for halos and glare, though less near vision. Contrast sensitivity was similar among the three lenses.ii
The Bausch & Lomb LuxSmart™ enhanced monofocal IOL uses non-diffractive technology combining two zones of opposite spherical aberration, which more than doubles the subjective depth of field. The BVI/Physiol ISOPure IOL enhanced monofocal uses aspherical anterior and posterior surfaces to increase negative spherical aberration, increasing depth of field and intermediate vision by one line compared with a monfocal lens.
The Mini Well® non-diffractive EDOF IOL incorporates three optical zones, including a central distance surrounded by distance with spherical aberration of the opposite sign to extend focus and a peripheral monofocal zone with a total add of +3.0 D. This results in a defocus of 0.8 decimal or better from +1.0 D to -2.0 D with mild glare and halos, Dr Nuijts noted.
The Alcon Clareon® Vivity® EDOF IOL uses a smooth wavefront-shaping element that continuously extends depth of focus.
A study Dr Nuijts conducted with colleagues found a binocular defocus curve of better than 0.1 logMAR from +0.5 D to -2.0 D with no halos, glare, or starbursts in more than 90% of patients when implanted using a minimonovision approach targeting -0.25 D to -0.5 D in the non-dominant eye.
For enhanced monofocal and EDOF lenses, Dr Nuijts looks for patients with a high demand for distance vision, significant activities at intermediate distance, and active and dynamic lifestyles desiring some degree of spectacle independence. Patients who are not candidates for diffractive technology and are risk-averse towards visual disturbances were also candidates.
Recent multifocal IOLs include the hybrid Tecnis Synergy™, which combines the good near and distance vision of a bifocal lens with complete vision over a range of distance and intermediate range of the Symfony, Dr Nuijts said. Compared with the PanOptix® trifocal lens, the Synergy delivered similar performance in distance, intermediate, and near visual acuity in one study, while another gave the edge to Synergy at intermediate and near distances.iii–iv
In searching for ideal candidates for trifocal PCIOLs, Dr Nuijts looks for a healthy eye with no corneal pathology, no severe corneal irregularities, and no diabetic retinopathy, macular pathology, or glaucoma. For enhanced monofocal or EDOF technology, he said he is more tolerant with inclusion. Trifocals still give the highest chance of spectacle independence for reading, but the trade-off is increased visual disturbances, though these are reduced in newer lenses.
Another option currently gaining favour in the United States is the AcuFocus IC-8® small aperture IOL. With the lens implanted in the non-dominant eye, most patients achieved distance, intermediate, and near vision of 20/32 or better, which was maintained for up to 1.5 D astigmatism in one study, Dr Nuijts said.v
Many accommodating IOLs have fallen by the wayside, either because they offer limited or no accommodation or lost accommodative power due to loss of flexibility in the capsular bag, Dr Beiko noted. Lens epithelial cells appear to play a role in maintaining capsular bag flexibility, and more research will be required to understand it. “Will there be an accommodating lens in the short term? I don’t think there will be,” he said.
Nonetheless, accommodating lenses are in development. The LensGen Juvene® has been approved for a pivotal clinical trial in the United States based, in part, on a study suggesting it retains accommodation for 24 months. The AkkoLens Lumina sulcusfixated accommodating lens is also planning market entry in Europe. It may bypass the issues of capsular bag fibrosis, said Jorge Alió MD, PhD.
Drugs that constrict the pupil offer another presbyopia solution. These include Allergan Vuity®, a pilocarpine solution. However, the effect is temporary and may not provide spectacle-free reading vision for patients with more advanced hyperopia, though they generally will improve intermediate vision. Side effects such as headache and eye irritation are also possible, and the drugs affect night vision. Several other agents that work by constricting the pupil are in development, as is a drop that softens the crystalline lens, restoring some flexibility to accommodate.
MONOVISION AND SPHERICAL ABERRATION OPTIMISATION
For younger presbyopic patients, LASIK monovision is an option, Dr Buratto said. He recommends a trial with contact lenses to assess patient tolerance. Monovision with monofocal lenses also can be effective, and it tends to enhance the near vision performance of EDOF lenses, several presenters noted.
Dr Beiko also recommends customising IOL selection based on individual patients’ pupil size and the degree of corneal SA. On average, unablated corneas have about 0.27 to 0.3 μm of positive SA. Combined with the positive SA of an IOL, this can add up to 0.5 to 0.6 μm of SA, which provides some pseudoaccommodation - though the effect is seen only in patients with larger pupils.
“If the pupil is small, I’ll target plano; if the pupil is large, I will target a refraction that balances the corneal SA or maximises the effect in the first eye. Then in the second eye I’ll purposely go for a little bit of myopia,” Dr Beiko said. This typically results in good distance vision and enough intermediate and near vision for daily activities and computer work but not enough for prolonged reading.
The process mimics natural pseudoaccommodation, which contributes significantly to near vision, Dr Beiko added. Many IOL manufacturers are working with SA to extend depth of focus in new designs, Dr Buratto noted.
i Vargas-Fragoso V, Alió J. Eye and Vision. 2017; 4(11).
ii Corbelli E. Journal of Cataract and Refractive Surgery. 2022; 48: 67–74.
iii Ferreira TB et al. Journal of Cataract and Refractive Surgery. 2022 Mar; 48(3): 280–287.
iv Dick HB et al. Journal of Cataract and Refractive Surgery. 2022 May 12. doi: 10.1097. epub ahead of print.
v Dick HB. Journal of Cataract and Refractive Surgery. 2017; 43(7): 956–968.
Lucio Buratto MD is a LASIK and cataract surgery pioneer and director of Centro Ambrosiano Oftalmico in Milan, Italy.
George HH Beiko BM, BCh, FRCS(C) is a lecturer at the University of Toronto and a cataract, refractive, and anterior segment surgeon practicing in St Catharines, Ontario, Canada.
Thomas Kohnen MD, PhD, FEBO is professor and chair, Department of Ophthalmology, Goethe University, Frankfurt, Germany.
Rudy MMA Nuijts MD, PhD is professor of ophthalmology, vice-chairman, and director of the Cornea Clinic and the Center for Refractive Surgery at the University Eye Clinic Maastricht, Maastricht Medical University, the Netherlands.
Wednesday, November 2, 2022