What kind of laser actually reshapes your cornea during LASIK? Which means most people don't think about it. They walk into a clinic, lie down, stare at a light, and twenty minutes later they can read the clock across the room. But the tool doing the work is one of the most precise instruments humans have ever built — and there's a real story behind why it's used.
Here's the short version: LASIK uses a femtosecond laser* to create the corneal flap, and an excimer laser* to reshape the underlying cornea. Two different lasers. Two different jobs. Both are essential, and the second one is arguably the more fascinating of the pair.
Let's break it down.
What Type of Laser Is Used in LASIK
The honest answer is that LASIK involves two lasers, not one. Still, surgeons use a femtosecond laser for the first step (creating a thin flap in the cornea) and an excimer laser for the second step (removing microscopic amounts of tissue to correct the refractive error). Some clinics still use a mechanical microkeratome blade for the flap — but the all-laser approach has become the modern standard.
Why two lasers? An excimer laser removes tissue at the surface through a process called photoablation* — basically, it vaporizes cells one microscopic layer at a time using ultraviolet light. Because each one does something the other physically cannot. A femtosecond laser creates incredibly precise cuts at a specific depth inside the cornea without generating heat. Neither job can be done well by the other.
Why It Matters Which Lasers Are Used
Not all lasers are created equal, and the specific models a clinic uses can influence your outcome. The femtosecond laser determines how cleanly your corneal flap is made — how thin, how uniform, how predictable. The excimer laser determines how smoothly your cornea is reshaped and how well the correction is sculpted.
A few things worth knowing:
- Faster lasers mean shorter procedures. Newer femtosecond lasers create flaps in under 10 seconds, reducing patient anxiety and surgical time.
- Wavefront-guided excimer lasers can create a custom correction meant for the unique imperfections of your eye — not just your prescription, but the higher-order aberrations that affect contrast and night vision.
- Eye-tracking technology in modern excimer lasers follows your eye hundreds of times per second. If you move during the procedure, the laser adjusts in real time. That matters more than people realize.
Real talk: the technology has gotten so good that complications from the laser itself are rare. Most of the variation in outcomes between clinics comes down to surgeon experience and pre-op screening, not the brand of laser on the wall.
How LASIK Works Step by Step
Here's what actually happens during the procedure, and where each laser comes in.
Step 1: Creating the Flap With a Femtosecond Laser
Your cornea has multiple layers. The surgeon needs to access the middle (the stroma) to reshape it. To do that, a thin flap is lifted — like opening a book cover.
The femtosecond laser fires pulses of infrared light at an astonishing rate. Plus, each pulse lasts about one femtosecond* — that's a quadrillionth of a second. And the pulses focus at a precise depth inside the cornea and create a layer of tiny bubbles. Those bubbles separate the tissue without cutting it.
Result: a flap that's remarkably uniform in thickness, with edges that fit back into place cleanly.
Step 2: Reshaping the Cornea With an Excimer Laser
Once the flap is folded back, the excimer laser gets to work. This is where the actual vision correction happens.
The excimer laser uses ultraviolet light at a wavelength of 193 nanometers — a wavelength so short that it breaks molecular bonds directly, without burning the surrounding tissue. Here's the thing — there's no heat damage. Each pulse removes a tiny amount of corneal tissue, typically less than the thickness of a human hair.
For nearsighted patients, the laser flattens the center of the cornea. Plus, for farsighted patients, it steepens it. For those with astigmatism, it makes the cornea more symmetrical. The whole reshaping process takes about 30 to 60 seconds per eye.
Step 3: Repositioning the Flap
After the excimer laser finishes, the surgeon folds the flap back into place. It adheres naturally — no stitches needed — and starts healing almost immediately.
That's the whole procedure. Painless, surprisingly fast, and the results are noticeable within hours.
Common Misconceptions About LASIK Lasers
Here's what most people get wrong.
"It's all done with one laser."
Nope. The all-laser technique uses two distinct devices. Older LASIK methods used a blade for the flap and a laser for the reshaping, but modern practices rely on two lasers working in sequence.
"The laser cuts or burns your eye."
It doesn't. The femtosecond laser also works without thermal damage. Here's the thing — the excimer laser is what's called a "cold laser" — it doesn't generate heat in the tissue it removes. Patients sometimes smell something during the procedure (a faint odor from the carbon released when tissue is vaporized), but no burning is happening.
"Any laser is just as good as the next."
Not really. While modern FDA-approved lasers are all safe, there are meaningful differences in spot size, repetition rate, eye-tracking capabilities, and customization options. A clinic using a 20-year-old excimer laser is not offering the same precision as one with current-generation wavefront-guided technology.
"The flap never fully heals."
This one is partially true, and worth understanding. The flap adheres strongly within days, but the edges of the flap never fully re-fuse the way the rest of the cornea does. This is why there's a small lifelong risk of flap displacement with direct trauma — something to keep in mind if you're a boxer, MMA fighter, or someone regularly exposed to eye injury risk.
For more on this topic, read our article on a characteristic you can observe about an object or check out phrs 564. drug delivery and nanomedicine ii pdf.
What Actually Matters When Choosing a Clinic
Forget the brand of the laser for a moment. Here's what really moves the needle.
Surgeon volume. A surgeon who's done 10,000 LASIK procedures will almost certainly produce better outcomes than one who's done 500. Ask about their numbers.
Pre-operative screening. The best clinics use multiple diagnostic tools to map your cornea, measure its thickness, and rule out conditions like keratoconus that can make LASIK a bad idea. If a clinic rushes this step, that's a red flag.
Post-operative care. The laser is just one piece. Follow-up appointments, monitoring for complications, and access to your surgeon if something feels off — these matter as much as the technology itself.
Honesty about candidacy. Not everyone is a good candidate. If a clinic tells you that, that's usually a sign they have integrity. If they tell you everyone's a candidate, run.
The laser is a tool. Now, a brilliant, expensive, fascinating tool — but still a tool. The hands holding it matter more than the box it comes in.
FAQ
Is LASIK done with a single laser or multiple lasers?
Modern all-laser LASIK uses two lasers: a femtosecond laser to create the corneal flap and an excimer laser to reshape the cornea. Some older or budget clinics still use a blade for the flap, but this is increasingly rare.
What is a femtosecond laser used for in LASIK?
The femtosecond laser creates the corneal flap. It fires ultra-short pulses of infrared light (each lasting about a quadrillionth of a second) to form a precise layer of microscopic bubbles inside the cornea, which separates the tissue cleanly without cutting.
Why is the excimer laser used to reshape the cornea?
The excimer laser emits ultraviolet light at 193 nanometers, a wavelength that breaks molecular bonds directly without generating heat. This allows it to remove tissue one microscopic layer at a time, sculpting the cornea into the precise shape needed to correct vision.
Do LASIK lasers hurt the eye?
No. Day to day, both lasers are "cold" — they don't burn or generate thermal damage. The procedure is painless, and most patients feel only mild pressure for a few seconds during flap creation.
How long does the laser part of LASIK take?
The actual laser time is remarkably short. On the flip side, the femtosecond laser creates the flap in about 6 to 10 seconds per eye. The excimer laser reshapes the cornea in roughly 30 to 60 seconds per eye, depending on the prescription.
So if someone asks you what kind of laser is used in LASIK, the answer is really two: a femtosecond and an excimer. But each one does something the other can't. Together, they've turned a once-rare surgical procedure into one of the most commonly performed in the world — and one of the safest.
seconds and nanometers.
What happens if I move during the laser?
Modern LASIK systems are equipped with real-time tracking and eye-tracking technology. That's why these systems monitor your eye movements thousands of times per second and automatically adjust the laser beam accordingly. This means even tiny involuntary movements are compensated for, ensuring precision throughout the procedure.
Can LASIK correct all types of vision problems?
LASIK is highly effective for correcting myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. Still, it cannot correct presbyopia—a natural aging condition that affects near vision—without additional techniques like monovision. Patients with severe dry eye syndrome or thin corneas may not be suitable candidates.
How soon can I see clearly after LASIK?
Many patients notice improved vision within hours of the procedure. On the flip side, it can take several weeks for the eyes to fully heal and stabilize. During this time, you may experience some fluctuations in vision, especially in low light conditions.
Are there long-term risks associated with LASIK?
When performed by experienced surgeons using advanced technology, LASIK has a strong safety profile. Long-term complications are rare but can include dry eyes, halos around lights, and under-correction or over-correction of the intended prescription. Regular follow-up care helps minimize these risks.
Is LASIK covered by insurance?
In most cases, LASIK is considered an elective procedure and is not covered by standard health insurance plans. That said, some employers offer reimbursement benefits, and many clinics provide financing options to make the procedure more affordable.
Making the Right Choice
Choosing LASIK isn't just about finding the latest laser technology—it's about finding the right team. In real terms, a advanced facility means little without skilled professionals who prioritize your safety and visual outcomes above all else. Take the time to research clinics, read patient testimonials, and don't hesitate to ask questions about their experience rates and complication protocols.
Remember, your vision is irreplaceable. Investing in a procedure that combines modern technology with exceptional patient care isn't just smart—it's essential. When done correctly, LASIK doesn't just correct your vision; it opens up a world where glasses and contact lenses become optional rather than necessary.
The future of vision correction continues to evolve, with advancements like wave-guided treatments and custom ablations offering even greater precision. But no matter how sophisticated the technology becomes, the foundation of successful LASIK remains constant: thorough evaluation, meticulous surgical technique, and comprehensive post-operative support.
Your journey to better vision starts with making informed decisions today.
