The excimer laser is a fluorinated argon dimer that, when excited by energy, produces an ultraviolet beam with a wavelength of 193 nm, which precisely ablates the part of the cornea that is expected to be removed without damaging the surrounding tissue or other organs, and because it is a cold laser, it does not have a thermal effect on the tissue next to the irradiated area. With this precise ablation, laser cutting does not penetrate the cornea, making it safer. As a result, there are no side effects on the tissues inside the eye and no side effects or after-effects. Two common types of excimer laser surgery are described below.
Excimer laser in situ keratomileusis
Excimer laser in situ keratomileusis is an advanced laser surgery developed on the basis of PRK. This method is based on the use of a microscopic corneal lamellar knife to create a tipped corneal flap with a thickness of 130 – 160 um on the cornea, then ablate the exposed superficial corneal stroma with an excimer laser, and then reset the flap to complete the surgical treatment. It is characterized by no significant postoperative pain, sore eyes, tearing and foreign body sensation for several hours. After the surgery, the vision recovers quickly, and the next day after the surgery, the vision is significantly improved. Post-operative eye medication only needs to be applied for half a month to one month.
Some places will promote the so-called “ultra-thin Lasik surgery”, which is actually relative to the previous conventional Lasik surgery. As we all know, Lasik surgery is to form a flap in the cornea and then form a smooth “concave biomirror” in the middle of the cornea (i.e., stroma) according to the refractive power, and then cover the flap with an alignment, the purpose of this is to prevent post-operative rebound, because the stroma is collagen fiber tissue and will not grow after being gasified. . In the process of forming the flap, conventional Lasik forms a 160um flap, while ultra-thin Lasik forms a flap of only 110um. If a normal person’s cornea is 500um, conventional LASIK will form a “concave lens” on the remaining 340um of the stromal bed, while Ultra-thin Lasik, on the other hand, forms a “concave biolens” on the 390um stromal bed, so that the thickness of the preserved cornea will be thicker and the chance of risk will be lower, and the safety of the surgery will be more guaranteed.
Subepithelial Excimer Laser Cutting
Lasek is a new surgical procedure that combines the advantages of PRK and Lasik. It involves creating a corneal epithelial flap approximately 50-80um thick, flipping it open, making an excimer laser cut underneath, and then repositioning the epithelium.
The patient’s postoperative reaction is slightly heavier than Lasik, with overnight eye pain, photophobia and tearing for about 1 day, and a slow recovery of vision, which is usually obvious about half a month after surgery. However, the advantage is that it is less traumatic to the cornea in the long run and more resistant to external forces.
Generally speaking, the two types of excimer laser surgery described here are recommended for patients with myopia of 500 degrees or less on the premise that the patient can accept Lasek surgery.
The following are some considerations related to excimer laser surgery for refractive error.
I. Excimer laser surgery indications.
1, age 18-50 years old;
2, myopia -1.00D – 12.00D, farsightedness +6.00D or less, astigmatism 4.00D or less;
3. Best corrected visual acuity not less than 0.5;
4. The refractive error is stable for more than one year;
5.No active eye lesions.
B. Notes before excimer laser surgery
1. Please do not wear hard or soft contact lenses within 2 weeks before surgery;
2, 3 days before surgery, please follow the doctor’s instructions to use antibacterial eye drops every day
3, pay attention to adequate rest, avoid eye fatigue, so as not to cause eye regulation spasm.
4, wash your face on the day of surgery, do not put makeup on your eyes to avoid difficulties in eye cleaning and disinfection before surgery; do not use perfumes, scented shampoos and any cosmetics with irritating odors to avoid affecting the working condition of the laser machine and affecting the results of surgery.
Three, excimer laser postoperative instructions
1.Don’t use tissues or towels to touch your eyes directly on the day after surgery;
2.Don’t remove the eye shield by yourself on the day of surgery, and don’t squeeze and rub your eyes;
3. Do not splash water into the eyes when washing your hair and face within 2 weeks after surgery, and do not rub your eyes;
4.Do not swim within 1 month after surgery, do not use cosmetics on the eye and avoid foreign objects entering the eye;
5.In order to reduce eye discomfort, you can wear wind-blocking glasses or sunglasses when you go out in the first month after surgery;
6.Avoid collision with the operated eye within three months after surgery;
7.Please pay attention to eye hygiene after surgery to avoid visual fatigue, which may affect the surgical effect.