Presbyopia is a condition that affects the accommodation properties of the eye. Generally, as objects move closer to a young, properly functioning eye, ciliary muscle contraction and zonular relaxation allow a crystalline lens of the eye to become rounder or more convex, and thus increase its optical power and ability to focus at near distances. Accommodation can allow the eye to focus and refocus between near and far objects. However, an eye affected by presbyopia often loses the ability to rapidly and easily refocus on objects at varying distances. The ability to focus on objects at near distances may also be lost. Although the condition progresses over the lifetime of an individual, the effects of presbyopia usually become noticeable after the age of 45 years. For example, the crystalline lens may lose a substantial amount of its elastic properties and may have a limited ability to change shape.
To address the vision problems associated with presbyopia, reading glasses have traditionally been used by individuals to add plus optical power to the eye and to allow the eye to focus on near objects and maintain a clear image. In alternative approaches, presbyopia has been at least partially corrected by the use of bi-focal eyeglasses, where one portion of an eyeglass lens provides correction for distance vision, and another portion of the eyeglass lens provides correction for near vision. Thus, with little or no accommodation, the individual can see both far and near objects. Contact lenses and intra-ocular lenses (IOLs) have also been used to treat presbyopia. For example, individuals have been provided with monovision (where one eye is corrected for distance-vision, while the other eye is corrected for near-vision) or bilateral correction with either bi-focal or multi-focal lenses. Although the aforementioned treatments have provided relatively successful results for correcting presbyopia, many of the aforementioned treatments, such as those in which eyeglasses and contact lenses are employed, provide temporary solutions for the individual. Additionally, implantation of IOLs introduces non-corneal tissue matter into the eye and may be relatively costly to perform.
Recently, ablation procedures have been explored as possible treatment solutions for mitigating presbyopic conditions. For example, certain ablation profiles have been suggested for treating presbyopia, often with the goal of increasing the range of focus of the eye. However, the suggested ablation profiles have typically included ablation dimensions requiring the removal of a substantial amount of corneal tissue, precluding some presbyopic individuals from qualifying for the ablation procedures.