Most people turn up to a sight test with their car keys and nothing else. They sit down, get asked how their vision has been, and say “fine, I think.” They leave with a prescription that is probably right and an eye health check that was probably thorough. The word doing all the work in that sentence is probably.
An eye test has two halves. One half is measurement and the equipment handles that regardless of what you bring with you. The other half runs entirely on what you can tell the optometrist. Whether the headaches arrive at 4pm or first thing. Whether your dad had glaucoma. Whether the reading glasses you actually wear are the ones you bought in a supermarket three years ago. None of that appears on a chart, and all of it changes what gets checked and how the results are read.
What you bring to the appointment is information nobody else can give.
What your optometrist is really trying to work out
Two questions sit underneath every sight test. Can you see as well as you should be able to, and are your eyes healthy? The first is the one you booked for. The second is the one that matters more, because most of the conditions worth catching early are quiet. Glaucoma does not hurt. Early changes at the back of the eye do not blur anything until they have already taken something away.
Your history is what tells the optometrist where to look harder, which is why “fine” is not much of an answer. Before you go, get specific with yourself. When do the symptoms turn up, morning or evening? One eye or both? Is it blur, or is it ache, or is it that the words start swimming after twenty minutes? Blur that appeared over a fortnight is a very different conversation from blur that has been creeping in since 2022.
Family history counts too, and people almost always forget to mention it. Glaucoma in a parent, brother, sister or child changes what happens in the room, and if you are 40 or over it also entitles you to a free NHS sight test. Macular degeneration in the family is worth saying out loud. So are diabetes, thyroid problems, high blood pressure, a head injury or a stroke.
Then there are your medicines. Some drugs mean the eyes need watching. Long term steroids can push eye pressure up. Hydroxychloroquine calls for regular retinal checks. Others matter later rather than now: tamsulosin is worth flagging because it can complicate cataract surgery years down the line. You do not need to know why any of that is true. You only need to say what you take, including eye drops, supplements and anything you take occasionally. Photograph the boxes on your way out of the bathroom and the job is done.
Booking the appointment: timing matters more than people expect
Pick a slot that catches your eyes at their worst
If your symptoms show up at the end of a working day, do not book 9am. You will arrive with rested eyes, everything will measure beautifully, and the problem will still be waiting for you on Thursday afternoon. A late slot after a normal day gives the optometrist the eyes that are actually giving you trouble.
Check whether someone else should be paying
Plenty of people pay for a sight test they were entitled to have for free. In England, NHS sight tests are free if you are under 16, or under 19 and in full time education, or 60 and over. They are also free if you have been diagnosed with diabetes or glaucoma, if you are 40 or over and a parent, sibling or child has glaucoma, if an ophthalmologist has told you that you are at risk of glaucoma, or if you are registered sight impaired or severely sight impaired. Several benefits qualify you as well, including Pension Credit Guarantee Credit, Income Support, income-based Jobseeker’s Allowance, income-related Employment and Support Allowance, and Universal Credit if you meet the earnings criteria. An HC2 certificate covers the full cost and an HC3 covers part of it. (Scotland runs a different system, where NHS eye examinations are free for everyone.)
Take proof with you. You will be asked to sign a form declaring your entitlement, so a benefit letter or exemption certificate saves an awkward moment at the desk. If you are unsure whether you qualify, ring the practice before you book and let them check.
There is a separate route if you use a computer for a meaningful part of your job. Employers have to cover the cost of an eye test for staff who use display screens, and they have to contribute towards glasses if the test shows you need a pair specifically for screen work. Most companies handle this with a voucher. Sort it out with HR before you book, because arriving without the paperwork usually means paying and then claiming it back.
Leave more room in the diary than a lunch break allows
A sight test on its own is quick. It is rarely the only thing happening. Retinal imaging adds time, dilating drops add more and rule out driving afterwards, and if you need new glasses, the measuring and fitting is a separate appointment in itself. Squeezing all of that into a lunch hour is how people end up rushing the one part that should never be rushed, which is the conversation at the start.
What to take with you
- Every pair of glasses you use. Distance, reading, computer, prescription sunglasses, and the old pair living in a kitchen drawer. Old lenses show how your prescription has moved, and now and then they reveal that the glasses you have been wearing were never made to the prescription you were given.
- Your contact lenses in their case, with the solution, plus the box or a photo of it. Brand, power and base curve are all printed on there, and none of it is worth trying to recite from memory.
- A photo of your medicine boxes. Quicker than remembering names, and it catches the ones you forget you take.
- Your employer’s voucher or form if work is paying for the test.
- Proof of entitlement if you are claiming a free NHS test.
- Your screen distance, measured with a tape measure from your eyes to the monitor at the desk you actually sit at. Add the distance you hold a book or a tablet. This is one of the most useful things you can bring and hardly anybody does it.
- Sunglasses, in case you have drops and walk out into a bright afternoon.
- Your previous prescription, or at least the name of the practice holding your records, if you are moving from somewhere else.
- A written list of your symptoms and the questions you want answered. You will forget them in the chair. Everybody forgets them in the chair.
Contact lens wearers: come as you actually are
There are two different appointments here and people mix them up constantly.
A routine sight test measures your eyes, not your lenses, so soft lenses usually need to come out beforehand. How long beforehand depends on the lens and the practice, so ask when you book. Rigid gas permeable lenses are the ones to plan around properly, because they sit directly on the cornea and can leave it slightly reshaped. You may be asked to leave them out for several days before an accurate reading is possible. Either way, bring your glasses. Walking out of a sight test unable to read the bus timetable is an avoidable problem.
A contact lens check is the opposite. Wear the lenses in, and wear the pair you have genuinely been wearing. Slipping in a fresh pair in the car park is a very common instinct and it defeats the whole point, which is to see how your lenses behave on your eyes after a normal day. The same goes for being straight about wear time. If you have been sleeping in your monthlies or pushing them a few weeks past their replacement date, say so. Nobody is going to tell you off, and those are precisely the habits the optometrist is looking for the effects of.
Taking a child for an eye test
Children rarely report a vision problem, because they have nothing to compare their vision against. As far as they know, everyone sees the world the way they do. The useful information comes from you and from school.
Book a slot when they are rested. Late morning usually beats the end of a school day. Reassure them first: no needles, nothing sharp, just some lights and some pictures. They also do not need to know their letters. Matching games, pictures and shapes work perfectly well for a child who cannot yet read.
What the optometrist wants from you is the pattern you have noticed at home. Sitting very close to the television. Tilting the head to one side. An eye drifting outwards when they are tired. Copying from the whiteboard taking far longer than it should. Reading that starts well and falls apart after ten minutes. Headaches on school days but not at weekends. Mention anything from the birth history, any squint or lazy eye in the family, and the school screening if they had one.
Expect the possibility of drops. Young eyes focus so strongly that the only way to measure them accurately is often to relax that focusing first, which leaves near vision blurry and eyes light sensitive for the rest of the day. Bring a hat or sunglasses, and do not plan on homework that evening.
Small habits that quietly skew the result
None of these ruin a test on their own. All of them make it harder to get exactly right.
Heavy eye makeup gets in the way. Mascara flakes into the tear film, lash extensions block a clear view at the slit lamp, and both make a pressure check more awkward than it needs to be. Go light, or go without.
Rubbing your eyes in the waiting room reddens them and disturbs the tear film for a good while afterwards. It is a hard habit to catch yourself doing, but try.
Skip the alcohol beforehand, including the night before if you can manage it. Tired, dehydrated eyes are not your eyes.
Do not perform on the letter chart. If you cannot read a line, guess. Guessing is expected and the optometrist is reading your guesses as information. Memorising the row above, which people genuinely do, only means you go home with the wrong prescription.
And when you reach the “which is better, one or two?” part of the test, you are allowed to say they look the same. Say it. That is a real answer and a useful one. The pressure people put on themselves to pick a winner is one of the more common ways a prescription ends up slightly off. There is no pass mark here and nobody is judging you.
When not to wait for a routine appointment
Some things need looking at today rather than in a fortnight when the booking system next has a slot:
- A sudden shower of new floaters, flashes of light at the edge of your vision, or a shadow or curtain drifting across your sight.
- Loss of vision in one eye, even briefly, and even if it has already come back.
- A red eye that is properly painful, especially with haloes around lights or with nausea.
- Sudden double vision, or an eyelid that has dropped.
- Any injury to the eye, including chemical splashes and anything that felt like grit and has not settled.
Ring the practice and describe what is happening rather than booking a routine test online. Many practices across Sheffield and South Yorkshire can see urgent eye problems on the NHS the same day, and if they cannot, they will tell you where to go instead. NHS 111 and the local eye casualty are the other routes.
After the test: the prescription is yours
Your written prescription belongs to you by law, and so does a statement saying you do not need one. You can take it anywhere. There is no obligation to buy glasses from the practice that tested you, on the day or at all, and a decent practice will never make you feel there is. Pupillary distance is a fitting measurement rather than part of the prescription, so ask for it if you want it, and do not be surprised if it is not offered automatically.
Before you leave, ask two things. What changed since last time, and does the change matter? A small shift in a prescription that has been stable for a decade is a different story from the same shift in an eye that has been moving every year. Then ask why they want to see you again when they do. A recall interval is a clinical judgement, not a marketing schedule, and if there is a reason behind yours you deserve to hear it.
If you drive, take the eyesight standard seriously. You have to be able to read a number plate from 20 metres, wearing your glasses or lenses if you need them, and meet a minimum standard of vision with both eyes open. The legal duty to tell the DVLA sits with you rather than with the optometrist. What the optometrist will do is tell you plainly if you fall short of it, and advise you not to drive until it is sorted out.
What good preparation actually buys you
An eye test is a conversation with measurements attached. The measurements happen whether or not you prepare. The conversation is the part you control, and it decides how much those measurements are worth.
That is becoming more true rather than less. High street practices now do work that used to belong in hospitals: retinal images stored and compared year on year, scans that look beneath the surface of the retina, urgent eye care delivered on the NHS from a shop you can walk into. Nearly all of it depends on comparison. An image on its own says very little. The same image alongside one from two years ago, next to a history that records what you take, what you do all day and who in your family had what, says a great deal. For a lot of people, the optometrist is now the first health professional to spot something that has very little to do with glasses.
So dig out the old pairs. Measure the desk. Write the questions down. Twenty minutes of preparation the night before is the difference between a routine appointment and a proper look at your eyes.
Frequently asked questions
How long does an eye test take?
Around 20 to 30 minutes for a standard sight test. Retinal imaging or a scan adds a little more, and choosing and fitting glasses afterwards is a separate 20 to 30 minutes. If drops are used, allow a couple of hours before your near vision settles down.
How often should I have my eyes tested?
Every two years for most adults. Every year if you are over 70, under 16, wear contact lenses, have diabetes or glaucoma, or your optometrist has asked you to come back sooner. If something has changed, do not wait for the reminder letter.
Will I be able to drive home afterwards?
Usually, yes. If dilating drops are used, no, and you should not drive for several hours. Ask when you book whether drops are likely, particularly for a first visit or if you have diabetes, and arrange a lift if they are.
Do I still need an eye test if my vision seems fine?
Yes. Glaucoma, raised eye pressure and early retinal changes are typically painless and produce no symptoms until damage has already been done. Sharp vision is not proof of a healthy eye.
Do I have to buy my glasses from the practice that tested me?
No. Your prescription is yours and you can take it wherever you like.
