What Happens During an Eye Test: Step by Step, How Long It Takes, and How to Prepare
A complete walkthrough of every step in a UK eye test. What the optician does, why each step matters, and what to bring with you.
How Long Does an Eye Test Take?
There is no industry standard, and the two chains that publish a figure are not measuring the same thing. Asda times the examination; Boots times the whole visit including choosing glasses. Specsavers and Vision Express publish nothing. Below is what each one says on its own page, with nothing added.
| Optician | What it publishes | What that covers |
|---|---|---|
| Asda Opticians | About 30 minutes | The examination itself. Asda's wording is that the test "will usually last about 30 minutes", during which an optical colleague and the optometrist run the checks. |
| Boots Opticians | Up to 1 hour 30 minutes | The whole visit. Boots' wording is "up to 1hour 30 minutes in total with your optometrist and team", covering pre-screening, the examination and shopping for glasses or lenses. |
| Vision Express | Not published | No appointment length on its eye test page. It does say the OCT 3D scan takes a few seconds and happens in the health screening just before the test. |
| Specsavers | Not published | No appointment length on its UK eye test page. Ask your store for its slot length when you book. |
Read from each chain’s own page on 19 October 2026, except Specsavers, whose site refuses automated requests from our server and was last read by hand on 2 October 2026. If a page starts publishing a figure, this table changes; we do not fill the gaps with an estimate.
Step-by-Step Walkthrough
The sequence is the same whether the test is NHS-funded or private. The minutes against each stage are our own guide to how a half-hour appointment is usually spread, not a published schedule: no optician publishes a stage-by-stage timing.
Arrival and Paperwork
5 minYou check in at reception, confirm your details, and complete a short questionnaire about your health, any medications, family eye history, and any visual symptoms. If you have a previous prescription, bring it along.
History and Symptoms
2-3 minThe optometrist asks about your vision since your last test, any problems (headaches, difficulty reading, dry eyes), your general health, and any medications. Be honest about symptoms, even minor ones.
Visual Acuity
2-3 minThe classic letter chart test. You read letters of decreasing size from a set distance (usually 6 metres, or reflected to simulate 6 metres in a smaller room). Tested with each eye separately and then both together. The result is expressed as a fraction such as 6/6 (normal) or 6/12 (reduced).
Refraction
5-10 minThe optometrist places a series of trial lenses in front of your eyes (using a phoropter or trial frame) and asks 'which is clearer, one or two?' for each combination. This determines your exact prescription for glasses or contact lenses. There is no wrong answer. Just say which looks better.
Eye Pressure (Tonometry)
1-2 minMeasures the pressure inside your eye. High pressure is a risk factor for glaucoma. Usually done with a puff of air (non-contact tonometry) or a small probe that briefly touches the eye (Goldmann tonometry). The puff of air is startling but completely painless.
Slit Lamp Examination
2-3 minA microscope with a bright, narrow beam of light examines the front structures of your eye: the cornea, iris, lens, and eyelids. You rest your chin on a support while the optometrist looks through the microscope. Checks for cataracts, corneal damage, and other conditions.
Retinal Examination
3-5 minThe optometrist shines a light into your eye (direct ophthalmoscopy) or uses the slit lamp with a special lens to see the retina, optic nerve, and blood vessels at the back of your eye. This can detect signs of diabetes, hypertension, macular degeneration, and retinal detachment.
Visual Field Test (if indicated)
3-5 minYou look straight ahead at a screen and press a button each time you see a small light flash at the edges of your vision. This maps your peripheral vision and is used to screen for glaucoma, strokes, and neurological conditions. Not always included in a routine test.
OCT Scan (if opted for)
1-2 minIf you have chosen the enhanced test with OCT, the machine takes a 3D scan of your retina. You rest your chin on a support and look at a target. The scan takes about 30 seconds per eye. Non-invasive and painless.
Results Discussion
3-5 minThe optometrist explains the results, whether you need glasses or a prescription change, any conditions found, and when to return. You receive a printed copy of your prescription. This is yours by right, even if you choose not to buy glasses there.
How to Prepare
To get the most from your appointment, bring the following:
After the Test
Your Prescription
You will receive a printed copy. It includes values for each eye: sphere (long/short sight), cylinder (astigmatism), axis, and addition (for reading, if needed). The prescription is valid for 2 years (or 1 year if you are under 16 or advised otherwise).
Pupillary Distance (PD)
The distance between your pupils, needed for ordering glasses. Opticians do not always include this on the prescription because it encourages you to buy from them. You can ask for it, or measure it yourself with a ruler and mirror. Online retailers provide measuring guides.
Do You Have to Buy Glasses There?
No. Your prescription belongs to you by law. The Opticians Act 1989 (as amended) requires the optician to give you a copy of your prescription at the end of the test, whether or not you buy glasses from them.
You can take your prescription to any other optician, or buy online from retailers such as Glasses Direct, SelectSpecs, or SmartBuyGlasses. Online glasses typically cost 50 to 70% less than high street prices for the same prescription.
The same right is what saves you a fee later: if you lose or break your glasses you can usually have replacements made from the prescription you already hold, without paying for another test.
The optician may apply some sales pressure. A polite "I would like to take my prescription and think about it" is perfectly acceptable.
How Often Should You Go?
| Group | Interval | Reason |
|---|---|---|
| Most adults (under 70) | Every 2 years | Standard recommendation from the College of Optometrists |
| Over 70 | Every year | Higher risk of age-related conditions |
| Diabetics | Every year | Diabetic retinopathy screening |
| Contact lens wearers | Every year | Corneal health and lens fit check |
| Children | Every year | Rapid vision changes during growth |
| Glaucoma risk | Every year | Monitoring for early changes |
| After cataract surgery | As advised | Post-operative monitoring |
If your vision changes noticeably between scheduled tests (new floaters, sudden blurring, flashing lights, distorted lines), do not wait. Book an appointment immediately or go to A&E if symptoms are severe and sudden.
Common Questions
How long does an eye test take?
Two of the big four publish a figure and they measure different things. Asda publishes "usually about 30 minutes" for the examination. Boots publishes "up to 1 hour 30 minutes in total", which covers pre-screening, the test and choosing glasses or lenses afterwards. Specsavers and Vision Express publish no appointment length on their UK eye test pages, so there is no national figure to quote. If you only want the examination, half an hour is the published benchmark; if you intend to look at frames, budget for the longer visit Boots describes.
Does an enhanced test with an OCT scan take longer?
A little. Vision Express describes the OCT 3D scan as taking a few seconds and says it happens during the health screening before the eye test rather than as a separate appointment. Boots says the length of the visit varies with which of its three tests you book, so the Advanced and Ultimate tests run longer than the Essential. Neither publishes a minute figure for the scan step itself.
Do I have to buy glasses from the optician who tested me?
No. Your prescription belongs to you. Under the Opticians Act 1989 the optometrist must give you a copy at the end of the sight test, and you can take it to any other optician or an online retailer. Ask for your pupillary distance measurement as well, because online retailers need it.