# What is Excimer Laser?

Source page: https://www.kudretgozistanbul.com/en/blog/eye-laser-treatments/what-is-excimer-laser

**Author:** Kudret Eye İstanbul | **Medical Approval:** Op. Dr. Mehmet Ali Özdil | **Date:** 2026-09-15

> **Summary:** The excimer laser is used in refractive surgery: it vaporises corneal tissue at a molecular level from the surface, changing the focusing power of the eye to remove myopia, hyperopia and astigmatism. It is chosen by people who want to reduce or end their dependence on glasses and contact lenses; the eye is numbed with drops, no general anaesthesia is used, and healing usually takes a few days.

## Quick Facts
- **Anaesthesia:** Numbing eye drops only, no general anaesthesia
- **Incision:** None by the excimer itself; in LASIK a flap is first lifted (with a femtosecond laser at Kudret Eye İstanbul)
- **Healing:** A few days, no stitches
- **Water restrictions:** No shower for the first 24 hours; no water, soap or shampoo directly in the eyes for the first week; no swimming pools or sea for about 20 days

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## What is Excimer Laser?
A laser method used in refractive surgery. It vaporises the cornea at the front of the eye at a molecular level, changing the eye's focusing power. When the refractive power of the cornea does not match the length of the eye, light cannot focus sharply on the retina; the excimer reshapes the curvature of the cornea. It corrects hyperopia, myopia and astigmatism. Femto LASIK (Laser Assisted in Situ Keratomileusis) is among the most widely used laser surgery methods.

## When is Excimer Laser Used?
- To correct refractive errors such as myopia, hyperopia and astigmatism, which glasses and contact lenses would otherwise correct for life.
- Not every eye or cornea is suitable. People with a very thin corneal layer, other eye conditions or an advanced condition are treated with other lasers or with intraocular, multifocal or trifocal lenses; patients whose cornea is unsuitable may be offered a multifocal lens or an ICL intraocular lens.

## Operations That Use Excimer Laser
- **Myopia:** the eyeball is longer than normal or the cornea too steeply curved, so light focuses in front of the retina and distance vision is impossible without glasses or lenses; the laser gives the cornea the curvature it needs.
- **Astigmatism:** an irregular curve and surface irregularities stop the cornea carrying light clearly to the back of the eye, blurring near vision and making distance vision difficult; the cornea is corrected to restore normal vision.
- **Hyperopia:** the eye is shorter than normal or the cornea flatter, making near objects hard to see and calling for reading glasses or lenses; the excimer removes the problem.

## How is Excimer Laser Applied?

### Before Treatment
- Examination by a specialist is essential: eye pressure measurement, corneal thickness analysis and assessment of the refractive state to identify any other problem.
- A treatment programme is prepared from the collected data; unsuitable corneas are directed to other treatments.

### During Treatment
- On the day of surgery the patient is examined and anaesthetic drops are placed in the eye; the patient generally feels only mild discomfort.
- Special instruments hold the eyelids open to prevent the blink reflex.
- In LASIK the thin surface layer of the cornea (the flap) is lifted with a femtosecond laser (more precise and controlled) or a microkeratome (mechanical blade); at Kudret Eye İstanbul the flap is created with a femtosecond laser. The excimer laser makes no incision: it reshapes the corneal tissue beneath the flap from the surface.
- The flap is laid back in place and heals by itself without stitches.

### After Treatment
- The eye heals naturally in a few days; use the prescribed drops exactly as directed and do not rub the eye.
- Do not shower for the first 24 hours; for the first week keep water, soap and shampoo out of the eyes; avoid swimming pools and the sea for about 20 days.
- Mild soreness as the drops wear off is normal and may pass within hours or last a few days; sunglasses may be needed and direct sunlight should be avoided.
- Blurred vision, haloes around lights and difficulty with night vision are normal during healing.
- Attend follow-up appointments on time and follow the surgeon's instructions.

## Risks of Excimer Laser Surgery
Risks are low and most side effects are temporary; the operation should be carried out in a sterile environment by specialist surgeons.
- Temporary dry eye: common in the first months; artificial tears relieve it and it usually settles on its own.
- Halos and glare at night: noticeable in the first weeks, usually disappearing as healing progresses.
- Under or over correction: if some prescription remains, an additional laser treatment (enhancement) can be carried out in suitable eyes.
- Infection: very rare; prevented with the prescribed drops and simple hygiene measures.