What Is SMILE Pro? How It Works, Explained for Patients

What the name means

SMILE stands for Small Incision Lenticule Extraction. Every word in that phrase describes something real, so it is worth unpacking.

Small incision

The surgeon reaches the tissue being reshaped through a narrow opening rather than by lifting a flap across the cornea.

Lenticule

A thin, lens-shaped piece of corneal tissue, carved out by the laser to a shape calculated from your prescription.

Extraction

Removing that piece. Taking it out is what flattens the centre of the cornea and changes where light focuses.

Pro

A platform generation, not a different operation. More on that in the technology section.

How SMILE Pro works

Refractive surgery works on a simple optical principle: if light focuses in front of the retina, the eye is short-sighted, and flattening the centre of the cornea moves that focal point back. SMILE achieves the flattening by removing tissue rather than adding it. Removing a lenticule of a specific thickness and profile produces a specific amount of flattening.

1. 01

   Consultation and eye examination

   Your refraction, corneal shape and thickness, tear film and general eye health are measured. This is where suitability is decided, not on the day of treatment, and not by a website.

   What the assessment covers

2. 02

   The laser creates the lenticule

   A femtosecond laser separates a thin, lens-shaped layer of tissue inside the cornea. The shape is calculated from your prescription. No flap is cut.

   How lenticule extraction works

3. 03

   The lenticule is removed

   The surgeon separates and withdraws the lenticule through a small incision. Removing that tissue is what changes the curvature of the cornea.

   The procedure in detail

4. 04

   Vision recovery and follow-up

   Vision usually improves quickly but keeps settling for weeks. Follow-up appointments track healing, refraction and the ocular surface.

   The recovery timeline

ZEISS, VISUMAX 800 and lenticule extraction

Three names come up constantly in SMILE marketing. Here is what each one actually refers to.

What is genuinely different about the newer generation?

The manufacturer describes the newer platform as faster, and as including automated features for centring the treatment and compensating for the eye's rotational position. Those are manufacturer descriptions of the device, which is a different kind of claim from an independent measured outcome.

Direct comparisons between the two generations exist in the peer-reviewed literature, but they are individual studies rather than pooled analyses, so they should not be read as settled. If a clinic charges a premium for the newer platform, the reasonable questions are which device is physically installed, and what that clinic's own outcome data shows.

Small incision, and what “flapless” really means

SMILE is often described as flapless, and technically that is correct: no hinged flap is created. But the word is sometimes stretched to imply that nothing structural happens to the cornea. That is not accurate, and it is worth being precise about.

• The cornea is still cut, and tissue is still permanently removed.
• The outer surface is left largely intact apart from the incision.
• There is no flap to reposition, and therefore no flap to displace later, which is a real difference from LASIK, not a marketing one.
• Fewer corneal nerves are cut because the incision is small. This is why dry-eye measures are often discussed favourably for the small-incision approach, though the evidence base is not unanimous and it does not mean dryness cannot occur.

In plain terms: LASIK opens the cornea like a book, works inside it, and closes it again. SMILE takes a small piece out through a keyhole. Both change the shape of the cornea permanently.

How it differs from LASIK

There are two structural differences, and almost everything else follows from them. LASIK creates a hinged flap and uses an excimer laser to reshape the tissue beneath it. SMILE creates no flap and uses a single femtosecond laser to carve out a piece of tissue which is then removed.

Who may be considered

SMILE may be considered for an adult whose prescription has stabilised, whose cornea is thick enough and of a normal shape, and whose ocular surface is healthy. Common reasons a surgeon declines include an unstable refraction, keratoconus or suspicious topography, significant dry eye, active eye disease, certain systemic conditions, and pregnancy or breastfeeding.

Eligibility is not a fixed threshold that produces the same answer in every clinic. Different surgeons apply different margins, particularly at the edge of the prescription range or with thinning corneas. You are entitled to ask where your measurements sit relative to that surgeon's limits, and to seek a second opinion if the answer is vague.

Read the full eligibility guide

What it may treat, and what it does not

• Short-sightedness (myopia). The primary indication, and the condition the technique was developed around.
• Myopic astigmatism. Astigmatism occurring alongside short-sightedness. Because astigmatism has a direction as well as an amount, the alignment of the treatment matters, and newer platforms include features intended to help with that.
• Astigmatism alone. A different question from astigmatism with myopia. Ask specifically whether that is something your surgeon treats.
• Long-sightedness (hyperopia). Not a routine indication for SMILE on the platforms in widespread use, although availability varies between markets and platform generations. Treat any clinic offering it as a signal to ask harder questions.
• Presbyopia. The age-related loss of reading focus affects everyone eventually and is not corrected by standard refractive surgery. Monovision and other approaches exist but are a separate conversation.

Consultation and screening

The assessment is the part of the process that determines your result, and it is the part clinics compress when they are busy. It should include refraction, corneal topography to map the surface shape, pachymetry to measure thickness, an assessment of the tear film and ocular surface, and a dilated examination of the back of the eye.

If your tear film needs treating first, surgery may be delayed until the surface has settled. That sequencing is a sign of care rather than an obstacle.

What a SMILE Pro consultation actually involves

Recovery in outline

Functional vision often improves quickly, and many patients describe a marked change within the first day. Refraction, however, keeps settling for weeks to months afterwards, so early fluctuation is expected rather than a sign of failure. Lubricating drops, screen breaks and following the surgeon's instructions on driving, exercise and water are the practical essentials of the first weeks.

The full recovery timeline, day 1 to long term

Potential risks and side effects

The commonly reported side effects are dry eye or grittiness, glare, halos and starbursts around lights, light sensitivity, and vision that fluctuates while healing. The recognised risks beyond that include residual refractive error, under- or over-correction, interface inflammation and (rarely) infection. Needing a further procedure is a possibility that is worth understanding before surgery rather than after.

We deliberately publish no complication rates. Rates differ between studies, populations and surgeons, and a figure drawn from someone else's population would not describe your risk.

Read the balanced risk guide