Safety and Effectiveness Study of the AcuFocus Corneal Inlay ACI 7000PDT in Presbyopes

The loss of near vision and the ability to perform tasks that require near vision is part of the normal aging process. This natural transformation in the eye occurs as a result of the loss of accommodation of the crystalline lens, a condition known as presbyopia. The crystalline lens is responsible for the accommodative properties of the human eye, as established by Young in 1801, over 200 years ago.1 During accommodation, the ciliary muscle contracts, decreasing tension on the zonules, and allowing the crystalline lens to thicken, increasing its refractive power. This mechanism of accommodation and thickening of the lens provides the eye with adequate refractive power for near vision. The loss of accommodation with aging is the result of changes in the crystalline lens composition that prevent the natural accommodative process from occurring. This is associated with the gradual loss of near vision without external correction, generally in the form of spectacles. The AcuFocus™ ACI 7000PDT represents new technology based on the well-established concept of small-aperture optics. In early cameras, depth of focus was controlled by reducing the aperture through which light enters. The smaller the aperture, the greater the depth of focus will be. This concept also applies to the human eye. In the eye of a presbyopic emmetrope, the lens cannot accommodate sufficiently to focus the light rays from a near object onto a single point on the retina. Thus, a point object is imaged as a blur circle on the retina, and images of extended objects are degraded as well. If an opaque disc with a small aperture in the center is placed in front of the eye, the peripheral rays will be obscured while the central rays pass unaffected. Since peripheral rays enter the eye at a larger angle, they create a larger blur circle at the retinal image plane. Eliminating these peripheral rays reduces the size of the blur circle, improving image resolution. In presbyopic subjects, objects closer than arm's length are focused behind the retina, thus creating blurred retinal images (which are composed of blur circles). A small aperture inlay placed in front of the eye of these subjects allows them to see at near by reducing the size of the blur circle. AcuFocus, Inc. has developed a stationary intracorneal inlay designed to create a small aperture effect. The implant is intended to be placed intra-stromally; the corneal flap will be newly created and fully lifted for presbyopic emmetropes. Placement of the ACI on the stromal bed centered over the pupil in the non-dominant eye is expected to increase the depth of focus of the eye by reducing the circle of blur. Based on theoretical calculations of small aperture optics, the ACI is expected to provide presbyopic subjects with improvement of near and intermediate vision.