Presbyopia correction program
A method of generating a computer program for control of an apparatus for photorefractive treatment of presbyopia by ablation of corneal tissue or a contact lens, comprising the following steps: (a) electing an eye model, (b) measuring the pupil diameter of the patient at far distance mesopically and at short distance photopically, (c) selecting wanted short and far distances regarding optimum sight, (d) calculating a global optimum regarding curvature (1/R) and asphericity (Q) of the cornea on the basis of the results obtained in steps (a) (b) and (c) by means of optical ray tracing and minimal spot diameter at the retina, and (e) deriving the computer program in accordance with the results of step (d). Alternatively step (d) includes determining a central steep island with a diameter in the range of 2 to 4 millimeters at the cornea and calculating a curvature and asphericity in the rest of the cornea.
1. A method of generating a computer program for control of an apparatus for photorefractive treatment of presbyopia by ablation of corneal tissue or a contact lens, the method comprising the steps of
(a) selecting an eye model,
(b) measuring the pupil diameter of the patient at far distance mesopically and at short distance photopically,
(c) selecting wanted short and far distances regarding optimum sight,
(d) calculating a global optimum regarding curvature (1/R) and asphericity (Q) of the cornea on the basis of the results obtained in steps (a) (b) and (c) by means of optical ray tracing and minimal spot diameter at the retina, and
(e) deriving the computer program in accordance with the results of step (d).
2. A method of generating a computer program for control of an apparatus for photorefractive treatment of presbyopia by ablation of corneal tissue or a contact lens, the method comprising the steps of
(a) selecting an eye model,
(b) measuring the pupil diameter of the patient at far distance mesopically and at short distance photopically,
(c) selecting wanted short and far distances regarding optimum sight
(d) determining a central steep island with a diameter in the range of 2 to 4 millimeters at the cornea and calculating a curvature and asphericity in the rest of the cornea and
(e) deriving the computer program in accordance with the results of step (d).
3. A method according to one of the claims 1 or 2 wherein said eye model is the Liou-Brennan model.
4. A method according to claim 1 , wherein in step (d) the global optimum is calculated such that the optical quality (sharpness) of the image at the retina is optimized for simultaneous optimum at the following conditions:
1.) far object and pupil diameter larger than 3, 5 millimeter and
2.) near object and pupil diameter of 2, 5 mm or less.
5. A method according to claim 2 , wherein in step (d) the determination is such that the optical quality (sharpness) of the image at the retina is optimized for simultaneous optimum at the following conditions:)
1.) far object and pupil diameter larger than 3, 5 millimeter and
2.) near object and pupil diameter of 2, 5 mm or less.
6. A method according to claim 2 , wherein in step (d) the central steep island has a refractive power of 2 to 4 diopters.