Pinhole Camera Effect in Small Aperture Implant Corrects Presbyopia in Patients

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When paired with extended depth-of-field multifocal technology, the IC-8 lens delivers extended depth of field in near, far and middle ranges while reducing halo and glare.

Special to the Ophthalmology Times

The IC-8 small aperture IOL (AcuFocus), which is CE marked and currently under study by the FDA, uses the pinhole camera effect to correct presbyopia.

By flattening the defocus curve of the myopic and hyperopic sides, the IOL essentially creates a small amount of myopia, thereby extending the patient’s depth of field and eliminating the visual effects of corneal astigmatism or other irregularities.

It is a one-piece hydrophobic acrylic eye implant that features an integrated opaque ring mask with a central opening. Aligned light rays converge through the central 1.36mm aperture, while defocused peripheral and often aberrated rays are blocked so as not to disturb the image.

Related: Presbyopia Correcting IOLs Improve Personalization

As a result, patients benefit from a continuous range of near to far vision, including the growing mid-range.

For most of us, the middle range (1.5 to 7 feet) is a critical activity area. We eat the majority of our meals, work at our desks and watch our big screen media in this space. This distance represents the area where many people make a living, including refractive surgeons.

Originally intended to be paired with monofocal IOL, it was found that when paired with multifocal IOL, IC-8 is better than previous alternatives at improving visual acuity at intermediate distances.

As a result, this lens has the potential to benefit this underserved cohort. Likewise, patients who have undergone previous refractive procedures are increasingly common.

As they proliferate, so too does our need for techniques and technologies tailored to meet their particular needs. IC-8 has shown good results in these “veteran” surgical patients.

Surgeons are only now beginning to appreciate the additional benefits made possible by the combination of the small aperture lens with IOLs that operate on completely different optical principles. Experimentation is ongoing and this new strategy could ultimately lead us to maximize the full potential of IOL, providing patients with truly satisfying personalized results.

Related: Changing focus of IOL adaptation now reaching a new level

Objective attributes
Low-add multifocal lenses have been shown to improve intermediate visual acuity and provide surgeons with the ability to further individualize patient visual outcomes, especially when mixed with other refractive technology. Combining a multifocal lens with another type of lens can also reduce glare and halo, an inherent characteristic of low-add multifocal optical lenses.

It is well known that most types of presbyopia correcting IOLs, including multifocal refraction and diffraction, and even the latest trifocal technology, sacrifice distance vision to some extent in order to correct near vision and induce a variable amount of dysphotopsia.1

A study of the AcrySof ReSTOR +2.50 D (Alcon) IOL found it to provide good intermediate and functional near vision for patients who did not want the higher potential for visual disturbances associated with the +3.00 version. D of the same IOL, but wanted greater near vision. that a monofocal IOL does not provide.2

Another prospective comparative study evaluated bilateral cataract surgery using AcrySof +3.00 D IOL or +4.00 D power of the implant.3

The +3.00 D IOL provided superior uncorrected distance visual acuity, significantly better uncorrected intermediate visual acuity at 40, 50, 60 and 70 cm, and functional reading acuity at 38.9 cm. Eyes with the +3.00 D IOL had better intermediate vision than those with the +4.00 D model without compromising distance and near visual acuity.

Related: Accurate Data Key for Planning Toric IOL Surgery

Multifocal extended depth of field
The Lentis Mplus LS-313 MF20 (Teleon; available in Europe but not the US) is a foldable, one-piece, aspherical, multifocal posterior chamber IOL that extends the patient’s depth of field. Its rotating asymmetric refraction design minimizes light loss to less than about 7%, improving contrast and retinal image quality.

An evaluation of the implant with +2.00 D close versus + 3.00 D found visual results far superior to nearly about 25 cm with this latter lens. The +2.00 D demonstrated excellent visual results from a long distance to an intermediate distance of about 50 cm.4

Related: Advanced Toric IOL Calculator Improves Refraction Results

Anchor with small opening approach
Unlike the aforementioned multifocal implants, the IC-8 IOL works through the pinhole effect. It reduces scattered light and only allows parallel rays to reach the macula. The depth of field is extended and visual disturbances such as glare and halo are reduced.

Small aperture technology can even overcome the problems of asphericity and corneal irregularities. Astigmatism up to 1.50 D can be corrected with the lens alone.5

The IC-8 IOL is usually implanted in the non-dominant eye, with a monofocal lens in the contralateral eye. To improve acuity, the small aperture IOL can be combined with other technologies such as a multifocal lens, a low-add multifocal lens, or even a trifocal lens.

The basic idea is that the use of different types of implants can improve the sharpness of near, intermediate and distance vision and minimize the side effects of competing technologies.

Related: IOL Correcting Presbyopia: Extend, Improve The Last Frontier

Small aperture, extended depth of field technology
The ongoing prospective multicenter MOSAIC clinical trial was undertaken to evaluate the visual outcomes of the combination of IOL IC-8 and Lentis MF20.6

Our group presented 5-month follow-up data on 13 patients with bilateral IC-8 IOL implantation with the Lentis LS-313 MF20 with +2.00 D close. We looked at the following parameters:

> uncorrected and corrected far, intermediate and near visual acuity (binocular);

> defocus curves;

> Reading test results at the Salzburg office; and

> photic phenomena (halo and glare simulator).

The MOSAIC trial included 26 eyes from 13 patients with cataracts (mean age, 68.5 ± 10.8 years). The target refraction for eyes implanted with the IC-8 IOL was -0.43 ± 0.18 D with an achieved refraction of 0.42 ± 0.41 D.

The refraction obtained was within ± 0.50 D 62% of the time. The target refraction for eyes implanted with the MF20 was -0.15 ± 0.16 D and the refraction achieved was -0.33 ± 0.42 D. Eighty-five percent of the time the refraction achieved was ± 0.50 D.

Related: Adjustable Light IOL Technology Creates New Treatment Window

We found that patients implanted with the LS-313 MF20 had excellent binocular visual acuity at long and intermediate distances, as well as functional near vision. They had functional reading acuity at near and intermediate distances, and there was a low incidence of photic phenomena.

The combination of the small aperture implant and a low addition multifocal lens such as the Lentis LS-313 MF20 is a good treatment option for patients motivated to become independent of glasses.

Implications and conclusions
Multifocal lens designs can have sharp peaks and valleys, but the IC-8 IOL provides uninterrupted functional vision over 3.00D of defocus.7

The small aperture principle has the ability to produce a full range of high quality vision without blurry areas and is more tolerant of refractive errors or surprises.

The IC-8 IOL implant has been shown to provide good visual results in post-LASIK and post-RK eyes.8 Patients with corneal irregularities can benefit from the technology’s ability to reduce aberrations.

When paired with multifocal extended depth of field technology, the IC-8 provides excellent extended depth of field at near, far and intermediate distances while reducing halo and glare. It can improve the ability of physicians to personalize successful visual results for each patient.

Based on the simple, proven and ancient understanding of the effect of the pinhole on the alignment of light rays, this IOL is a versatile tool to help patients who have had cataract surgery achieve their critical postoperative visual goals.

Read more content on the cornea here

Gerd U. Auffarth, MD, PhD, FEBO
E: [email protected]
Dr Auffarth is Chairman and Medical Director of the Ophthalmology Department at the University Clinic in Heidelberg, Germany; director of the David J. Apple, MD, International Laboratory of Ocular Pathology; and director of the International Center for Vision Correction in Heidelberg. He receives research grants and conference fees from AcuFocus, Alcon, Biotech, Hoya, Johnson & Johnson, KOWA, Oculentis, Rayner and Zeiss.

The references:

Gundersen KG, Potvin R. Comparative visual performance with monofocal and multifocal intraocular lenses. Clin Ophthalmol. 2013; 7: 1979-1985.

de Vries NE, Webers CA, Montés-Micó R, Ferrer-Blasco T, Nuijts RM. Visual results after cataract surgery with implantation of a diffractive aspherical multifocal intraocular lens +3.00 D or +4.00 D: comparative study. Cataract refraction surgery J. 2010; 36 (8): 1316-1322.

Linz K, Attia MS, Khoramnia R, et al. Clinical evaluation of reading performance using the Salzburg reading office with a refractive rotating asymmetric multifocal intraocular lens. J Thrust refraction. 2016; 32 (8): 526-532.

Venter JA, Pelouskova M, Bull CE, et al. Visual results and patient satisfaction with a rotating asymmetric refractive intraocular lens for emmetropic presbyopia. Cataract refraction surgery J. 2015; 41 (3): 585-593.

Calvo-Sanz JA, Sünchez-Tena MA. Characterization of optical performance with defocus curve: analysis of two models of high and medium addition refractive intraocular lenses. J Opt. October 31, 2018.

https://www.healio.com/ophthalmology/cataract-surgery/news/online/%7B2809ee76-e466-43fe-b70b-dd94ff661925%7D/video-edof-iol-using-pinhole-effect-lessens-ocular-effects .

Dick HB, Elling M, Schultz T. Binocular and monocular implantation of small aperture intraocular lenses in cataract surgery. J Refract Surg. 2018; 34 (9): 629-631.

Dick HB. Small opening strategies for the correction of presbyopia. Curr Opin Ophthalmol. 2019; 30 (4): 236-242.


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