Who Can't Have Laser Eye Surgery?

Anyone considering laser eye surgery asks one question first: "Am I a suitable candidate?" An equally important question is the opposite: when does laser stop being an option? A laser suitability assessment settles this, but most people want the general picture before booking that appointment.

Who Should Not Have Laser Eye Surgery?

When the cornea's structure suits no laser method, surgery isn't recommended, and glasses or contact lenses remain a safe alternative. Under eighteen, laser is usually postponed because the prescription hasn't stabilised — what matters isn't age itself, but stability confirmed through measurement. If topography shows an irregular curvature, or there's suspicion of a progressive corneal disease such as keratoconus, laser is generally avoided, since it could weaken the cornea further, and a different approach is considered instead. Topography that changes noticeably over time, or progressing rapidly in one eye, is examined separately to rule out an underlying disease.

Why Does Corneal Structure Matter So Much?

All three methods — PRK, femtosecond LASIK and SMILE (KLEx) — remove or reshape some corneal tissue. If thickness is insufficient, it's unclear whether the remaining tissue can safely support clear vision long term. Femtosecond LASIK cuts a flap, so a minimum thickness is required; SMILE's incision is much smaller, but the cornea still has to be structurally suitable. TransPRK creates no flap, so it's more flexible for a thinner cornea, but if the cornea is too thin or irregular, none of the three, PRK included, may be safely recommended. These figures aren't judged in isolation either — they're weighed against how much tissue the refractive error would require removing, so two corneas of equal thickness can give different outcomes.

Why Isn't Laser Recommended When Your Prescription Isn't Stable?

Laser corrects the prescription as measured at that moment; if it's still changing, it risks rising again after surgery, leaving the correction incomplete. That's why an unchanged prescription for the last year or two is a shared precondition across all three methods. Younger patients see prescription change more often, so this group is monitored until stability is confirmed by measurement, at which point laser can be reconsidered. Even when a prescription seems unchanged for years, that isn't assumed without measurement; the objective reading from the suitability assessment gives an independent starting point.

Does Dry Eye Rule Out Laser?

Dry eye alone doesn't rule out laser, but it's always assessed and can affect which method suits you best. In methods that interrupt the cornea's nerve network — particularly those with a larger flap — dry eye can be somewhat more likely; a smaller incision tends to limit this effect. If existing dry eye is significant, treating it beforehand may be recommended, which helps the overall outcome. For patients who are pregnant or breastfeeding, the procedure is usually postponed too, since hormonal changes can temporarily affect clarity of vision — a matter of timing, not a permanent barrier.

How Do You Get a Definite Answer?

None of the above amounts to a definite "no" without an assessment — each is a warning sign to be reconsidered through detailed measurement. Once corneal thickness, topography, dry eye severity, intraocular pressure and the health of the back of the eye are examined together, it's clear which method can be used safely, or whether laser isn't suitable for now. Patients previously turned down elsewhere can also be reassessed with current techniques; since equipment and methods keep improving, a past result may no longer hold true. So no permanent decision rests on a single measurement.

Which Method Is Ruled Out, and When?

Alongside the criteria above, some situations rule out only one of the three methods, not all of them. For patients with hyperopia, SMILE isn't a clinical option, so the assessment moves straight to TransPRK or femtosecond LASIK. When corneal thickness isn't enough for a flap, femtosecond LASIK is ruled out and flapless PRK comes to the fore instead. Exclusions like these don't mean laser is unsuitable altogether — they simply narrow down which method will be considered for you. Our guide to which laser method suits you covers this in more detail.

The result isn't a simple yes-or-no answer either; one method may suit a patient while another doesn't, which is why the findings are always reviewed with the patient in detail.

Is Laser Eye Surgery Worth It? What Regrets in Reviews Have in Common

Most reviews from people who have had laser eye surgery are positive, and studies also report high satisfaction among suitable candidates. There are still reviews that say "I regret it" or "my symptoms never went away", and they often share the same root: the suitability assessment before surgery.

The complaints mentioned most often in negative reviews are dry eye, halos around lights at night and some remaining prescription. They connect directly to the barriers described in this article: dry eye that existed before surgery and was not treated, corneal thickness that was borderline for laser, or a prescription that had not yet stabilised all make these complaints more likely.

When reading reviews, it is also worth checking which method was used and when. PRK, femtosecond LASIK and SMILE have different recovery courses, and an experience with a technique used many years ago may not fully reflect today's technology.

Whether laser eye surgery is worth it for you is decided by the measurements of your own eyes, not by other people's reviews. A comprehensive suitability assessment including corneal topography, thickness measurement and dry eye tests is the most reliable way to anticipate possible complaints in advance.

For more detail on this topic, see Laser Suitability Assessment on how the assessment is carried out