Femtosecond Laser Photodisruption of the Crystalline Lens for Restoring Accommodation

Presbyopia is defined by the progressive loss of accommodation and subsequently reduced ability to achieve a near focus when distance corrected. This progressive change, despite beginning in childhood, is almost universally clinically relevant after the fifth decade, being responsible for a significant decrease in quality of life. The number of people affected by presbyopia is growing fast due to aging of the population. The mechanism of accommodation is very complex, and the adequate understanding of how it actually works is the first step toward the development of an effective procedure to reverse it. The most widely accepted theory was proposed by Helmholtz and confirmed by more recent studies in primates. It states that the movement of the equatorial edge of the lens is away from the sclera during accommodation and toward the sclera during disaccommodation. To accommodate, a contraction of the ciliary muscle releases the resting tension on the zonular fibers. It releases the equatorial tension on the lens capsule and allows the elasticity of the lens proteins and capsule to change its shape. This causes a decrease in the circumferential lens diameter and increases the curvature of the anterior and posterior lens surfaces. When the ciliary muscle relaxes (ceasing the accommodative effort), it moves toward the sclera pulling the zonular fibers and increasing the tension