Before the operation, the doctor inputs the patient's basic information and operation data into the computer (including the depth of laser focusing, that is, the distance from the bottom of the cone lens to the laser focusing point; The diameter of corneal flap, the size and width of pedicle; Energy of laser cutting, etc. During the operation, the doctor operates the femtosecond laser and fixes the cornea with a cone lens, so as to keep the precise distance between the laser head and the laser focusing point in the corneal tissue.
Laser focus depth, that is, the distance from the bottom of the cone lens to the laser focus, the femtosecond laser emits laser pulses according to the mode set by the doctor, and makes various targeted cuts on the cornea. In a word, what impressed us most about the optical transmission principle of femtosecond laser is the precise orientation and precise positioning of optical transmission.
2. The principle of light blasting
Laser pulse is focused on corneal tissue, resulting in light explosion; Each light explosion pulse produces a micro ion, and each micro ion evaporates about 1 micron of corneal tissue; Evaporating corneal tissue produces expanded blisters and CO2 bubbles, which are absorbed by corneal tissue, so corneal tissue is separated.
The computer-controlled optical transmission system generates thousands of laser pulses, which are focused at the same depth according to the dense grating pattern with equal width and equal spacing, resulting in light explosion, which forms a layer of tiny diameter bubbles in corneal tissue, separating corneal tissue and forming the corresponding separation surface, that is, the cutting surface of femtosecond laser.
Matters needing attention in expanding data
(1) Before the operation, the patient should clearly explain the purpose and requirements of his operation to the doctor, and know whether he is suitable for the operation and the possible effects after the operation.
(2) Understand the general process of the operation and the possible situations during and after the operation.
(3) After deciding the operation with full understanding of the operation risks, sign the consent form.
(4) Before operation, soft contact lenses (contact lenses) should be stopped for 1-2 weeks, and hard contact lenses should be stopped for 3 weeks.
(5) Topical application of antibiotic eye drops 3 days before operation.
(6) Gaze training should be carried out before operation, so as to cooperate with doctors during operation.
(7) Have enough sleep the night before myopia surgery.
(8) Wash your face on the day of operation, and don't make up your eyes, so as to avoid the difficulty of cleaning and disinfecting your eyes before operation. If it is not thoroughly cleaned, some fine particles will enter the operation area. Do not use perfume and cosmetics with irritating smell, so as not to interfere with the working state of the laser machine and affect the effect of the operation.
(9) Do not wipe or touch your eyes with your hands after local eye disinfection before operation.
(10) When waiting before operation, relax, don't be nervous, and don't talk or talk loudly in the preparation room, so as to avoid excessive excitement and emotional loss during operation, which will affect the operation effect.
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