Corneal Ring Implant Improves Near Vision

A novel intrastromal corneal implant uses small aperture optics to correct presbyopia in certain patients who have not had cataract surgery.

The KAMRA inlay is a microscopically thin disc, just 3.8 mm in diameter, with a 1.6-mm wide central aperture that improves near vision when placed in the non-dominant eye. This is intended to allow the patient to have improved near vision in the non-dominant eye containing the implant, while not affecting the distance vision when both eyes work together. The inlay extends depth of focus by using small aperture optics, blocking peripheral unfocused light rays while allowing central light rays to pass through the central aperture of the device.

The disc inlay design includes 8,400 microscopic openings that surround the central aperture, allowing oxygen and nutrients to flow freely and naturally through the eye. KAMRA is indicated for phakic, presbyopic patients 45–60 years of age who have cycloplegic refractive spherical equivalent of +0.50 to -0.75 D, with less than 0.75 D refractive cylinder, who do not require glasses or contact lenses for clear distance vision, and who require near correction of +1.00 D to +2.50 D of reading addition.

To insert the inlay, an ophthalmologic surgeon first creates a pocket in the cornea with a laser, placing the inlay in that pocket. Clinical studies have shown that 83.5% of the evaluable 478 participants achieved uncorrected near visual acuity of 20/40 or better at 12 months, a level of vision needed to read most text in magazines and newspapers. Over 20,000 KAMRA inlays have been implanted worldwide to date. The KAMRA inlay is manufactured by AcuFocus (Irvine, CA, USA; www.acufocus.com), and has been approved by the US Food and Drug Administration (FDA).

“The small aperture effect is a globally accepted method for vision correction. The KAMRA inlay is the ideal solution for presbyopic patients who don’t want or require lens removal,” said Jim Mazzo, executive chairman and CEO of AcuFocus. “The KAMRA inlay not only delivers patients a long-lasting, full range of vision, it provides surgeons with a minimally invasive, reliable solution to fill a notable gap in their practice offering—namely presbyopia correction.”

Presbyopia is a condition associated with aging in which the eye exhibits a progressively diminished ability to focus on near objects. Presbyopia’s exact mechanisms are not fully understood; research evidence most strongly supports a loss of elasticity of the crystalline lens, although changes in the lens’s curvature from continual growth and loss of power of the ciliary muscles (the muscles that bend and straighten the lens) have also been postulated as its cause.

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