Abstract / Synopsis: 

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

Special to Ophthalmology Times

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

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

This is a 1-piece hydrophobic acrylic ocular implant that comprises an embedded opaque annular mask with a central aperture. Aligned light rays converge through the 1.36-mm central aperture, while peripheral defocused and, often, aberrated rays are blocked from disrupting the image.

Related: Presbyopia-correcting IOLs enhance customization

As a result, patients experience a continuous range of vison from near to far, including the increasingly important intermediate range. 

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

Originally intended to be combined with a monofocal IOL, it has been found that when paired with a multifocal IOL, the IC-8 is better than previous alternatives at enhancing 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 becoming more common. 

As they proliferate, so does our necessity for techniques and technologies tailored to support their special needs. The IC-8 has shown good outcomes in these “veteran” surgical patients. 

Surgeons are only now beginning to appreciate the additional benefits made possible by combining the small-aperture lens with IOLs that function on completely different optical principles. Experimentation is ongoing, and this novel strategy may ultimately lead us to maximize the full potential of the IOL, providing patients with truly satisfying customized outcomes.

Related: Changing focus of accommodating IOLs now reaching a new level 

Lens attributes
Low-add multifocal lenses have been shown to improve intermediate visual acuity and offer surgeons the ability to further individualize patients’ visual outcomes, especially when mixed with another refractive technology. Combining a multifocal lens with a different type of lens can also act to minimize glare and halo, an intrinsic characteristic of low-add multifocal lens optics. 

It is well known that most types of presbyopia-correcting IOLs—including multifocal refractive and diffractive, and even the newest trifocal technology—sacrifice distance vision to some extent in order to correct near vision and induce a variable amount of dysphotopsias.1

One study of the AcrySof ReSTOR +2.50 D IOL (Alcon) found it provided good intermediate and functional near vision for patients who did not want the higher potential for visual disturbances associated with the +3.00 D version of the same IOL but wanted more near vision than a monofocal IOL provides.2

Another prospective comparative investigation evaluated bilateral cataract surgery using the +3.00 D AcrySof IOL or a +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

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 outcomes after cataract surgery with implantation of a +3.00 D or +4.00 D aspheric diffractive multifocal intraocular lens: comparative study. J Cataract Refract Surg. 2010;36(8):1316-1322.

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

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

Calvo-Sanz JA, Sánchez-Tena MA. Characterization of optical performance with defocusing curve: analysis of two refractive intraocular lens models with high and medium addition. J Optom. 2018 Oct 31. 

https://www.healio.com/ophthalmology/cataract-surgery/news/online/%7B280….

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

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