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    Presbyopia therapy: Comparison of corneal versus lens-based options

    For the appropriate surgical candidate, the KAMRA corneal inlay offers a long-term solution for presbyopia, with demonstrated outcomes and long-term safety features

    Take-home: The authors assess the quantitative and qualitative aspects of vision following various lens- and corneal-based therapies for presbyopia. In many cases the KAMRA corneal inlay offers a long-term solution. It can easily be removed if the patient is not satisfied with the outcome.

    At some point, everybody aged over 40 will experience the effect of the progressive loss of accommodation as the crystalline lens loses its ability to increase its dioptric power at near vergence, a condition known as presbyopia. Globally, presbyopia is projected to increase to 1.4 billion by 2020 and to 1.8 billion by 2050; 1 it represents the most common human ocular affliction.

    In our technology-reliant world, any vision deficit at intermediate or near affects quality of life and can hinder daily activities critical to both professional and personal tasks. Increasingly, patients elect to have refractive procedures performed independently, or concurrently with cataract removal or clear crystalline lens replacement, in an effort to decrease or eliminate their dependence on reading glasses or bifocals. To meet this growing demand and satiate rising consumer expectations for corrective vision surgery, industry is responding with new corneal and lens-based surgical innovations, including small-aperture corneal inlays and accommodating and multifocal intraocular lens implants. We performed a study to assess the quantitative and qualitative aspects of vision at different vergences with these lens- and corneal-based options.

    Related: Was 2015 the year of inlays, FLACS, or something else?

    Small-aperture optics

    figure1Small-aperture optics is predicated on the same concept as adjusting the aperture of a camera, whereby increasing the f-stop (i.e., creating a smaller aperture) enhances depth of focus. The KAMRA intracorneal inlay (AcuFocus, Irvine, California, USA) is similarly designed to increase depth of focus by blocking unfocused peripheral light rays, thereby reducing the size of the macular blur circle. The inlay is made from polyvinylidene difluoride and has an inside aperture of 1.6 mm and an outside diameter of 3.8 mm. It is 6 microns thick and is fenestrated with 8400 holes in a pseudorandom pattern to facilitate the exchange of glucose and other metabolites (Figure 1). It is implanted in a corneal pocket with a depth of at least 200 microns, created using a femtosecond laser. The result of small-aperture optics is an extended range of continuous vision spanning near, intermediate and far (Figure 2). This differs from the mechanism of action of multifocal and accommodating IOL designs that address presbyopia following cataract or clear lens extraction. Current accommodating IOLs, such as Crystalens Advanced Optics (AO; Bausch + Lomb Surgical, Aliso Viejo, California, USA), produce excellent distance and intermediate vision but are limited and variable in their range of accommodation and generally do not produce as good a monocular near visual acuity as multifocal lens designs. Multifocal IOLs distribute light among multiple energy foci for near and far distances, thereby improving near visual acuity over the standard monofocal IOL. However, there are several inherent potential disadvantages to multifocal IOLs, including reduced contrast sensitivity, degraded image quality and photic visual symptoms such as glare/haloes. 2

    Small-aperture inlay vs presbyopia-correcting IOLS 

    Jay S. Pepose, MD, PhD
    Jay S. Pepose, MD, PhD is Director of the Pepose Vision Institute and Professor of Clinical Ophthalmology and Visual Sciences at ...

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