Am I eligible for LASIK? Age, power and corneal thickness limits

“Am I eligible for LASIK?” is a very common question, usually followed by three more: Am I old enough? Is my power too high? Are my corneas thick enough? They are the right questions. Here are the answers, and what the alternatives are if the answer is no.

Age: usually 18+, and stable

LASIK is for adult eyes. The general rule is 18 and above, but age alone isn’t the real test, stability is. Your prescription should have been more or less steady for about a year. If your power is still climbing, reshaping the cornea now just means you’d be short-sighted again later. That is why the last year or two of prescriptions are reviewed.

There’s a soft upper end too. From the mid-40s, you start needing reading glasses (presbyopia) regardless of LASIK, so the conversation shifts to what you want from your vision. LASIK can still be suitable, it’s just a fuller discussion.

Power: there’s a safe range, not a magic number

LASIK corrects short-sight, long-sight and astigmatism, but only within a safe range, because correcting more power means removing more corneal tissue. As a rough guide, laser can correct short-sight up to around -8.00 to -10.00, depending on the eye, with smaller limits for long-sight and astigmatism.

The key words are depending on the eye, because power and thickness are linked. Which brings us to the limit that matters most.

Corneal thickness: often the real deciding factor

This is the limit people least expect. LASIK works by removing a thin layer of corneal tissue, and your cornea has to be thick enough to give up that tissue and still have a safe, strong amount left behind.

• A thick, healthy cornea gives the laser room, and may safely allow a higher correction.
• A thin cornea can rule LASIK out even at a modest power.

That’s why two people with the same glasses number can get different answers: their corneas are different. Thickness is measured and the corneal shape is mapped before anything is decided, never from the prescription alone. It is also how eyes are screened for keratoconus, an irregular, weak cornea that rules laser out entirely.

If LASIK is not suitable, there may be other options

Being told “no” to LASIK does not always mean glasses are the only choice. Sometimes a different route fits the eye:

• SMILE Pro: flapless laser, which may cause less post-operative dryness in some eyes. An option for many short-sighted eyes.
• ICL: an implanted lens that removes no corneal tissue, often considered for high power or thin corneas.

Each of these has its own limits and risks, and some eyes are not suitable for any of them.

The only real way to know

Every limit above is a guide, not a verdict. What settles it is a refractive suitability assessment: your prescription, corneal thickness and shape, and dry-eye status, measured together. The result may be LASIK, another procedure, or no surgery for now.