SMILE Pro vs PRK: Two Very Different Recoveries

PRK is the oldest of the three main refractive procedures and the one that has changed least. It is often described as the option nobody wants because the recovery is uncomfortable, and that reputation, while not unreasonable, obscures why PRK is still performed deliberately in situations where it is the better choice.

What does PRK involve?

PRK stands for photorefractive keratectomy. The surgeon removes the thin outer layer of the cornea (the epithelium) over the area to be treated, then uses an excimer laser to reshape the tissue beneath it. The epithelium regrows over the following days.

There is no flap and no lenticule. The laser works directly on the corneal surface, and the surface heals back over it.

How does that compare with SMILE Pro?

SMILE Pro keeps the surface layer largely intact, cutting a lenticule inside the cornea and removing it through a small incision. PRK removes the surface layer entirely and reshapes the tissue underneath.

The consequence is a different recovery curve. In PRK, the eye is waiting for its outer layer to regrow before it is comfortable and before vision stabilises. That period is the source of PRK’s reputation: discomfort, light sensitivity and slow visual improvement over the first days, sometimes longer.

SMILE Pro tends to be more comfortable earlier, though it has its own pattern of fluctuation and its own first-day sensations.

So why would anyone choose PRK?

Three reasons, and they are clinical rather than financial.

Thin corneas. Because PRK does not need to create a flap, the tissue arithmetic differs. In some eyes, the amount of tissue available favours PRK over a flap-based procedure. This is a measurement question, not a preference.

Corneas where a flap is a poor idea. Irregular or unusually shaped corneas, or eyes with certain surface conditions, may be better served by a surface procedure. Epithelial basement membrane dystrophy is a common example where a clinician may steer away from a flap.

Where a flap has already existed. After LASIK, if a retreatment is needed, the options are usually to lift the existing flap or to perform a surface procedure. PRK on top of a previous LASIK correction is an established approach.

There is also a practical consideration: PRK does not require a femtosecond laser, so it can be offered where a clinic does not have one.

Which is better for dry eyes?

Both procedures disturb the corneal surface, and both can be followed by dry-eye symptoms. The relevant studies do not support a simple ranking in favour of either.

What matters more than the technique is what happened before it. Someone with significant pre-existing dry eye is a challenging candidate for any refractive procedure, and the sensible sequence is to treat the surface first and reassess, rather than to select a technique in the hope it avoids the issue.

What about the risk of haze?

PRK has a recognised association with corneal haze during healing, particularly with higher corrections. Modern technique and post-operative protocols, including the use of mitomycin C in selected cases, have reduced it substantially, but it remains a consideration that a surgeon should discuss when it is relevant to your prescription.

SMILE does not carry the same haze consideration, for the straightforward reason that the surface layer is not removed.

What this means for you

If a clinic suggests PRK and you had expected to hear about SMILE or LASIK, the useful response is to ask why. The answer should be specific and measurable (the thickness numbers, a topography finding, a previous procedure) rather than a general preference. If it is specific, you are being given good advice, even if it is not the advice you wanted.

If a clinic offers you a choice between all three without explaining how your measurements led to that shortlist, ask which measurements would change the answer. A surgeon thinking in those terms will tell you; a sales process will not.

The comparison page covers all three procedures across twelve categories, and the eligibility page explains the measurements that drive the choice.