Patent ID: 7887531

Claim:
A method of controlling an excimer laser unit to perform cornea ablation to reduce presbyopia, the method comprising the step of: a) controlling said excimer laser unit to produce on the cornea a photoablative pattern inducing a fourth-order ocular aberration; wherein said induced fourth-order aberration is a spherical aberration; and wherein said step a) further comprises the steps of: a1) acquiring and interpreting an aberrometric map of the eye indicating the visual defects of the eye, said visual defects comprising second-order visual defects including hypermetropia, astigmatism, and myopia, and higher-order visual defects including spherical aberration, thereby detecting a fourth-order spherical aberration; a2) if the detected spherical aberration is negative, supplying said excimer laser unit with an overcorrect photoablative pattern that results in an induced fourth-order positive spherical aberration after treatment, the overcorrect photoablative pattern being obtained by obtaining a photoablative pattern to correct a fourth-order spherical aberration that is increased numerically in absolute value from the detected fourth-order spherical aberration; a3) if the detected spherical aberration is positive, supplying said excimer laser unit with an overcorrect photoablative pattern that results in an induced fourth-order positive spherical aberration after treatment, the overcorrect photoablative pattern being obtained by obtaining a photoablative pattern to correct a fourth-order spherical aberration that is opposite in sign and increased numerically in absolute value from the detected fourth-order spherical aberration; and a4) controlling said excimer laser unit to implement the overcorrect photoablative pattern on said cornea.