Patent ID: 6887231

Claim:
A computer readable media including a control program, according to which a laser-beam spot is guided, while being controlled with respect to position and time, over a cornea to be corrected, so as to ablate a predetermined ablation profile therefrom, comprising: instructions to take into account the effect of the angle between the laser beam ( 68 ) and the corneal surface on the energy density of the laser-beam spot incident on the corneal surface, wherein the time interval the laser-beam spot is incident on the corneal surface at an incident point ( 58 ) of the corneal surface is increased as a function of the distance (r) of the incident point ( 58 ) of the laser-beam spot centre on the cornea ( 54 ) from an axis running parallel to the laser-beam direction which axis meets the corneal surface at a right angle (z axis), wherein the effect of the distance r of the incidence point ( 58 ) of the laser-beam spot centre on the cornea ( 54 ) from an axis running parallel to the laser-beam direction which meets the corneal surface at a right angle (z axis), is taken into account, and account is taken of the fact that the energy density F of the emitted laser-beam spot of radius r s is reduced to F/kl(r), in the case of a cornea assumed to be hemispherical with radius R, when incident on its curved surface ( 54 ), where k1 â¡ ( r ) = A eff â¡ ( r ) A 0 = A eff â¡ ( r ) Ï€ Â· r s 2 and A eff â¡ ( r ) = âˆ« - rs rs â¢ âˆ« rs 2 - x 2 + r - rs 2 - x 2 + r â¢ 1 + ( â…† â…† x â¢ f â¡ ( x , y ) ) 2 + ( â…† â…† y â¢ f â¡ ( x , y ) ) 2 â¢ â…† x â¢ â…† y with z=f ( x,y )= f ( r )=âˆš{square root over ( R 2 âˆ’x 2 âˆ’y 2 )}=âˆš{square root over ( R 2 âˆ’r 2 )}, r =( x 2 +y 2 ) 1/2 where x, y, z are the coordinates of the incidence point ( 58 ) of the laser-beam spot centre in a Cartesian coordinate system, in which the origin lies at the sphere centre of the cornea which is assumed to be hemispherical.