How the pinhole effect of a small opening implant corrects presbyopia

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When combined with multifocal extended depth of field technology, the new small aperture ocular IOL, IC-8, provides excellent extended depth of field at near, far and intermediate distances while reducing halo and glare.

A new small aperture ocular IOL, IC-8 (Acufocus), which is CE marked and currently under review by the United States Food and Drug Administration (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.

This high-tech hydrophobic acrylic one-piece eye implant 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.

As a result, patients benefit from a continuous range of near to far vision, including the growing mid-range. At 1.5 to 7 feet away, the Intermediate Beach is a critical activity zone for most people. This is where we eat most of our meals, do our office work, and watch the majority of our media on the big screen. This is where many people make their living, including refractive surgeons.

Originally intended to be combined with a monofocal IOL, it was found that, when combined with a multifocal IOL, the IC-8 is better than previous alternatives in improving visual acuity at intermediate distances, and has hence the potential to benefit this underserved cohort. . Likewise, patients who have already undergone 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.Objective attributes

LOW ADDED HONEYS
Low Addition Multifocal Lenses (MIOL) 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 intrinsic characteristic of MIOL optics.

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 IOL (Alcon) found that it provided good intermediate and functional near vision for patients who were unwilling to accept the higher potential for visual disturbances associated with the +3 version, 00 D of the same IOL, but wanted a closer view than a monofocal IOL usually does.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.

MF EXTENDED FOCUS DEPTH
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 distance at an intermediate distance of around 50cm.4Anchor with small opening approach

Unlike the aforementioned multifocal implants, the IC-8 IOL works thanks to the pinhole effect: by reducing the scattered light and allowing only parallel rays to reach the macula, the depth of field is extended and visual disturbances such as the 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

Typically, the IC-8 IOL is 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. There are many combinations to consider, the basic idea being that using different types of implants can improve the sharpness of near, intermediate and far vision, and minimize the side effects of competing technologies.

Small aperture technology and EDOF
The ongoing prospective, multicenter Mosiac study was undertaken to assess the visual outcomes of the combination of IOL IC-8 and Lentis LS-313 MF-20.6 Our group presented 5-month follow-up data on 13 patients with bilateral IC-8 IOL implantation with the Lentis LS-313 MF-20 with +2.00 D close. We looked at the parameters, including:

  • Uncorrected and corrected far, intermediate and near visual acuity (binocular);
  • Salzburg Reading Office; and
  • Photic phenomena (halo and glare simulator).

The 26 eyes of 13 cataract patients with a mean age of 68.5 ± 10.8 years were included. The targeted refraction for the eyes of 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 the MF-20 eyes was -0.15 ± 0.16 D and the refraction achieved was -0.33 ± 0.42 D. The refraction achieved was within ± 0.50 D 85% of time.

We found that the patients had excellent binocular visual acuity at long and intermediate distance, as well as functional near vision. In addition, they had functional reading acuity at near and intermediate distances, and there was a comparatively low incidence of photic phenomena (see Figures 1 and 2). The combination of the small aperture implant with a low addition multifocal lens like the Lentis LS-313 MF-20 is a good treatment option for patients who are motivated to become independent of glasses.Implications and conclusion

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 it is more tolerant of refractive errors or surprises.

The implant has been shown to provide good visual results in post-LASIK and post-RK eyes8, making it an attractive option for patients who previously could not find a suitable IOL to correct presbyopia. Likewise, patients with corneal irregularities can benefit from the technology’s ability to reduce aberrations.

When paired with Multifocal Extended Depth-of-Field (EDOF) technology, the IC-8 delivers excellent EDOF at near, far and in-between distances while reducing halo and glare. It can improve the physician’s ability to personalize successful visual results for each patient, even for those who have had refractive surgeries before. 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 cataract patients achieve their critical postoperative visual goals.

Disclosures:

1. Gundersen KG, Potvin R. Comparative visual performance with monofocal and multifocal intraocular lenses. Clin Ophthalmol. 2013; 7: 1979-1985.
2. 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. J Refractory cataract surgery. 2010; 36 (8): 1316-1322.
3. 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 Refract Surg. 2016; 32 (8): 526-532.
4. Venter JA, Pelouskova M, Bull CE, et al. Visual results and patient satisfaction with a rotating asymmetric refractive intraocular lens for emmetropic presbyopia. J Refractory cataract surgery. 2015; 41 (3): 585-593.
5. 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.
6. https://www.healio.com/ophthalmology/cataract-surgery/news/online/%7B2809ee76-e466-43fe-b70b-dd94ff661925%7D/video-edof-iol-using-pinhole-effect-lessens-ocular -effects.
7. 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.
8. Dick HB. Small opening strategies for the correction of presbyopia. Curr Opin Ophthalmol. 2019; 30 (4): 236-242.

GERD U. AUFFARTH, MD, FEBO
E: [email protected]
Professor Auffarth is Chairman and Medical Director of the Department of Ophthalmology, Heidelberg University Clinic, Heidelberg, Germany, Director of the David J. Apple, MD International Laboratory of Ocular Pathology, and Director of the International Vision Correction Research Center in Heidelberg. He receives research grants and conference fees from Alcon, Johnson and Johnson, Zeiss, Hoya, Oculentis, Rayner, Acufocus, KOWA and Biotech.


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