One year is the federal floor, not the universal rule. Several states require two, and a prescriber can write less than a year only with a documented medical reason. The clock starts at issue, not at your first order.
What federal law requires
The FTC Contact Lens Rule (16 CFR Part 315) sets the minimum validity at one year from the date of issue — unless state law requires longer, or your prescriber documents a medical reason for a shorter period.
Two details that matter:
- The clock runs from issue. Wait four months to order and you have eight left.
- Shortening it requires justification. A prescriber cannot write six months simply to bring you back sooner; there has to be a clinical finding behind it.
The states that require longer
Several set a two-year minimum for healthy adults. The rule that applies is the one in the state where the prescription was written, not where you buy.
We keep the state-by-state breakdown with the statutory citations in expiration by state. If your prescription says one year but you live in a two-year state, it is worth asking — a seller goes by what is written on the document.
Why there is an expiry at all
Not a mechanism for selling exams. Three concrete reasons:
Your prescription changes. Most in the teens and twenties, and again after 40 as presbyopia arrives. An out-of-date power causes eye strain and headaches.
The fit changes. Corneal curvature and tear film are not static. A lens that fitted well three years ago can be gripping now — and a tight lens does not necessarily feel tight.
Some things do not hurt. Corneal neovascularisation, papillae on the inner lid, epithelial thinning. All silent early, all visible under a slit lamp. That examination is the part you cannot do for yourself, and it is the real product of the annual visit.
Contact lens and glasses prescriptions are separate
Different documents, different expiry dates. A contact lens prescription adds base curve, diameter and a specific brand, because the lens sits on your eye rather than 12 mm in front of it — and the powers differ above about ±4.00 dioptres for the same reason.
See why one will not do for the other and how to read yours.
If it has expired
No legitimate seller can fill it. That is federal law, and it applies however long you have shopped with them. There are sensible options — see ordering with an expired prescription.
How not to be caught out
- Set a reminder at ten months, not twelve.
- Photograph the prescription the day you get it — the issue date is what counts, and you are entitled to a copy automatically; see your rights.
- Book the exam and buy the supply together so the prescription and any insurance benefit renew on the same cycle — see how vision plans work.
- Use FSA or HSA funds — the exam is an eligible expense too.
Sources
- FTC Contact Lens Rule, 16 CFR Part 315 — §315.6(a), §315.3
- State optometry statutes — see the state-by-state guide
General information, not legal or medical advice. Reviewed by Dr. Teresita Bollar, OD.
