LASIK vs PRK vs SMILE: How to Choose the Right Laser Eye Surgery

Laser vision correction has helped millions of people reduce or eliminate their dependence on glasses and contact lenses. Yet choosing between the main options, LASIK, PRK and SMILE, can feel confusing, especially when clinics advertise their own preferred procedure as the best. In reality, each technique has strengths and weaknesses, and the right choice depends on the shape and thickness of your cornea, your prescription, your lifestyle and your tolerance for recovery time.

This guide explains how each procedure works, who is likely to be a good candidate, what recovery looks like, and which risks deserve careful thought. It also covers implantable collamer lenses (ICL), an important alternative for people who are not suitable for laser treatment, and finishes with a list of questions to take to your consultation.

The basics: how laser eye surgery corrects vision

Most people who need glasses for distance have a refractive error: light is not focused precisely on the retina because the eye is too long, too short, or the cornea is unevenly curved. The cornea, the clear dome at the front of the eye, provides about two-thirds of the eye's focusing power. By removing a precise, microscopic amount of tissue from it, a laser can change its curvature and move the focus onto the retina.

• For myopia, the central cornea is flattened.
• For hyperopia, the central cornea is steepened by removing tissue around it.
• For astigmatism, the cornea is reshaped to be more evenly curved.

The key difference between LASIK, PRK and SMILE is how the surgeon gets access to the deeper corneal tissue, and that difference drives the variations in recovery and risk.

LASIK: the flap technique

In LASIK (laser-assisted in situ keratomileusis), the surgeon first creates a thin hinged flap in the cornea, usually with a femtosecond laser, though some clinics still use a mechanical blade (microkeratome). The flap is lifted, an excimer laser reshapes the underlying corneal stroma, and the flap is laid back down. It adheres naturally without stitches.

Strengths

• Rapid visual recovery: many people see well the next day and return to work within a day or two.
• Little pain after surgery; usually only a few hours of irritation.
• Long track record and very predictable results for low to moderate prescriptions.
• Can treat myopia, hyperopia and astigmatism.

Limitations

• The flap never heals to full strength, so a hard blow to the eye can dislodge it, even years later. This matters for contact sports, martial arts and some professions.
• Cutting the flap severs corneal nerves, which contributes to dry eye after surgery.
• Requires enough corneal thickness to leave a safe residual bed under the flap.

PRK: surface treatment

PRK (photorefractive keratectomy), along with related surface procedures such as LASEK and trans-epithelial PRK, was the original form of laser vision correction. Instead of a flap, the thin outer skin of the cornea (the epithelium) is removed with alcohol, a brush or the laser itself. The excimer laser then reshapes the surface directly, and a bandage contact lens is placed while the epithelium regrows over several days.

Strengths

• No flap, so no risk of flap complications and better suited to people at risk of eye trauma.
• Preserves more corneal thickness, making it an option for some people with thinner corneas.
• Long-term visual results are broadly comparable to LASIK.

Limitations

• Recovery is slower and more uncomfortable: pain, light sensitivity and watering are common for the first few days.
• Vision fluctuates and may take several weeks to fully stabilise.
• There is a risk of corneal haze, especially with higher corrections; surgeons may use medicines during surgery to reduce this.
• Steroid eye drops are often needed for weeks to months, which requires monitoring of eye pressure.

SMILE: keyhole lenticule extraction

SMILE (small incision lenticule extraction) and similar newer lenticule procedures use only a femtosecond laser. The laser creates a thin disc of tissue, called a lenticule, inside the intact cornea. The surgeon then removes it through a small incision of a few millimetres, changing the shape of the cornea.

Strengths

• No flap, so the upper corneal layers remain largely intact and biomechanically stronger.
• Smaller incision cuts fewer corneal nerves; studies suggest dry eye may be less pronounced early on than with LASIK, though results vary.
• Recovery is fast, generally similar to LASIK within days.

Limitations

• Originally approved for myopia and astigmatism; treatment of hyperopia is newer and not available everywhere.
• Enhancement (touch-up) procedures are more complex than lifting a LASIK flap, often requiring PRK on the surface.
• The technique depends heavily on surgeon experience; visual recovery in the first day or so can be slightly slower than LASIK for some patients.
• Shorter long-term follow-up than LASIK and PRK, although results to date are good.

Side-by-side comparison

Who is a good candidate?

Laser surgery is elective, and a responsible clinic should turn away people who are not suitable. Typical criteria include:

• Age: usually at least 18, and ideally with a prescription that has been stable for at least one to two years.
• Prescription within the treatable range: limits vary by technique and laser, and outcomes tend to be best for low to moderate prescriptions.
• Healthy, sufficiently thick cornea with a regular shape on corneal topography or tomography scans.
• No active eye disease such as uncontrolled dry eye, active infection, significant cataract or uncontrolled glaucoma.
• Stable general health: some autoimmune diseases, uncontrolled diabetes and certain medicines can impair healing.
• Not pregnant or breastfeeding, as hormonal changes can temporarily alter the prescription.
• Realistic expectations: the goal is reduced dependence on glasses, not guaranteed perfect vision for life.

Signs of keratoconus or an abnormally thin or irregular cornea are generally a reason to avoid LASIK and SMILE, because removing tissue could weaken the cornea further.

The risks in detail

Dry eye

Dry eye is the most common side effect of all laser procedures. Corneal nerves that help regulate tear production are cut or disrupted, and it takes months for them to recover. Most people need lubricating drops for the first few weeks or months, and symptoms usually improve within six to twelve months. A minority have persistent symptoms. People who already have dry eye disease should have it treated and controlled before surgery, and may be steered towards surface treatment or ICL.

Glare, halos and night vision

Many patients notice halos or starbursts around lights at night in the first weeks. This usually fades as the eye heals. Persistent symptoms are more likely with large pupils, high corrections or smaller treatment zones. Modern lasers with wavefront-optimised or topography-guided profiles have reduced, but not eliminated, these problems.

Under- or over-correction and regression

Not every eye responds exactly as planned. A small residual prescription may remain, or the effect may regress over time, particularly with higher corrections and hyperopic treatments. Some people need an enhancement procedure.

Corneal ectasia

Ectasia is a rare but serious complication in which the weakened cornea gradually bulges forward, similar to keratoconus, causing worsening and distorted vision. The main defence is careful pre-operative screening to identify corneas at risk. If ectasia occurs, treatments such as corneal cross-linking and specialty contact lenses can help stabilise and correct vision.

Other complications

Infection, inflammation under the flap, flap folds and epithelial ingrowth are uncommon. Serious sight-threatening complications are rare, according to major ophthalmology organisations, but they are not zero, and you should be told about them during consent.

ICL: the lens-based alternative

An implantable collamer lens (ICL), sometimes called a phakic intraocular lens, is a thin artificial lens placed inside the eye, in front of your natural lens and behind the iris. It does not remove corneal tissue at all.

• Suitable for high myopia beyond the comfortable laser range, thin corneas, some forms of stable keratoconus, and people with significant dry eye.
• Advantages: excellent optical quality in many patients, preserves the cornea, and is potentially removable.
• Risks: as an intraocular procedure, it carries small risks of raised eye pressure, cataract formation, inflammation and, very rarely, infection inside the eye. Regular follow-up is required.

For people over about 45 to 50, refractive lens exchange, in which the natural lens is replaced with an artificial lens similar to cataract surgery, may be discussed as another option.

Questions to ask your surgeon

1. Which procedure do you recommend for my eyes, and why not the others?
2. Do you offer all three techniques plus ICL, or only some of them?
3. What are my corneal thickness and topography results, and do they show any warning signs?
4. What results do you expect for my prescription, and what is my chance of needing an enhancement?
5. How many of these procedures have you personally performed?
6. What are the specific risks of dry eye and night vision problems in my case?
7. Who handles follow-up care and complications, and is it included in the price?
8. What happens if my vision changes in the future?
9. Can I have a copy of my pre-operative measurements for my records?

When to see a doctor

After any refractive surgery, contact your surgeon or seek urgent care if you notice:

• Increasing pain, redness or discharge, especially after the first day or two.
• Sudden worsening of vision or a new shadow, curtain or shower of floaters.
• Severe light sensitivity that is getting worse rather than better.
• Any significant blow to the eye, particularly after LASIK.
• Gradually worsening or distorted vision months or years later, which could indicate ectasia.

Choosing between LASIK, PRK and SMILE is ultimately a medical decision made together with an experienced surgeon after detailed measurements. Understanding the differences helps you ask better questions and choose with confidence, or to decide that glasses or contact lenses remain the best option for you.