Procedure of LASIK:
First, the eye is numbed with a few drops of topical anesthetic. An eyelid holder is placed between the eyelids to keep them open and prevent the patient from blinking. A suction ring placed on the eye lifts and flattens the cornea and helps keep the eye from moving.
Once the cornea is flattened, a hinged flap of corneal tissue is created using an automated microsurgical device, either a laser or blade. This corneal flap is lifted and folded back (figure 1). Then the excimer laser preprogrammed with the patient's unique eye measurements is centered above the eye.
The surgeon checks that the laser is positioned correctly. The patient looks at a special pinpoint light, called a fixation or target light, while the excimer laser sculpts the corneal tissue. Then the surgeon places the flap back into position and smoothens the edges. The corneal flap sticks to the underlying corneal tissue within two to five minutes, and …show more content…
When pulsed ultraviolet light, at wavelengths below 350 nm, is applied in the nanosecond (ns) range it causes breaks in the intermolecular bonds of the polymer chains of corneal collagens, disintegrating the target tissue. The resulting small volatile fragments are propelled at high speed above the tissue surface, where they can be evacuated. (figure 3) This process does not involve a significant increase in the tissue temperature as the diffusion time for heat conduction into the surrounding tissue is much longer than the millisecond (ms) range pulse duration. The energy of the laser light is almost entirely absorbed at the surface of the treated tissue without producing relevant collateral effects within the stroma. The current used excimer laser has a wavelength of 193 nm, where corneal tissue has the maximum absorption in UV range. It also has smaller focal point and provides better accuracy compared to long wavelength
First, the eye is numbed with a few drops of topical anesthetic. An eyelid holder is placed between the eyelids to keep them open and prevent the patient from blinking. A suction ring placed on the eye lifts and flattens the cornea and helps keep the eye from moving.
Once the cornea is flattened, a hinged flap of corneal tissue is created using an automated microsurgical device, either a laser or blade. This corneal flap is lifted and folded back (figure 1). Then the excimer laser preprogrammed with the patient's unique eye measurements is centered above the eye.
The surgeon checks that the laser is positioned correctly. The patient looks at a special pinpoint light, called a fixation or target light, while the excimer laser sculpts the corneal tissue. Then the surgeon places the flap back into position and smoothens the edges. The corneal flap sticks to the underlying corneal tissue within two to five minutes, and …show more content…
When pulsed ultraviolet light, at wavelengths below 350 nm, is applied in the nanosecond (ns) range it causes breaks in the intermolecular bonds of the polymer chains of corneal collagens, disintegrating the target tissue. The resulting small volatile fragments are propelled at high speed above the tissue surface, where they can be evacuated. (figure 3) This process does not involve a significant increase in the tissue temperature as the diffusion time for heat conduction into the surrounding tissue is much longer than the millisecond (ms) range pulse duration. The energy of the laser light is almost entirely absorbed at the surface of the treated tissue without producing relevant collateral effects within the stroma. The current used excimer laser has a wavelength of 193 nm, where corneal tissue has the maximum absorption in UV range. It also has smaller focal point and provides better accuracy compared to long wavelength