What is refractometry and how does it work?
Refractometry (also called refraction testing) is the eye test that measures how your eye focuses light and gives the prescription for glasses or contact lenses. A normal eye bends light so that it lands exactly on the retina. If the eye is too long, too short or unevenly curved, the image falls in front of, behind or across the retina, which causes short sight (myopia), long sight (hyperopia), astigmatism or, with age, presbyopia. Refractometry finds the lens power, in dioptres, that brings the image back into focus. The result is written as sphere, cylinder, axis and, for reading, an addition. The test uses an automatic instrument, a light-reflex method called retinoscopy and a subjective check in which you compare lens choices. It is a diagnostic test, not an operation, and eye clinics in Turkey perform it routinely and as the first step before many treatments.
This guide explains each step, how accurate the readings are, when eye drops are needed, what the test costs compared with the UK, US and Germany and how the result is used. For the wider choice of eye care see our eye treatments in Turkey.
When is a refractometry test needed?
- Blurred vision or eye strain: difficulty reading, driving or seeing the board; headaches after near work.
- New or changed glasses: a prescription that no longer feels right, usually checked every one to two years.
- Before laser or lens surgery: the measurement decides whether and how a refractive procedure is planned.
- Before and after cataract surgery: to choose the lens power and check the final focus.
- Children: to detect long sight or a difference between the two eyes that can cause a lazy eye (amblyopia) or squint.
- Monitoring: in progressive short sight, keratoconus or after eye surgery.
The NHS and the College of Optometrists advise a regular eye test every two years for most adults, and sooner for children, for people with diabetes and for anyone with a change in vision.
How accurate is refractometry? What the evidence says
Refractometry is a mature, well-validated measurement. An autorefractor gives a quick, objective starting point and is generally close to the final prescription in adults, but it can over-measure short sight because the eye tends to focus when looking at the instrument's target. Retinoscopy, in which the examiner watches how light reflects from the retina, is a reliable objective method, especially in children who cannot answer questions. The subjective step, where you choose between lens options, remains the reference for the final prescription because it reflects how you actually see. Where the eye can focus strongly, as in children and young adults, drops that relax focusing (cycloplegic refraction) give the true measurement. A careful refraction does not, however, replace a full eye examination: it does not detect glaucoma, retinal disease or early cataract.
Refractometry cost in Turkey compared with the UK, US and Germany
The ranges below are approximate figures for the test alone, not clinic quotes. Prices differ with the equipment, the examiner, whether eye drops are used and whether the refraction is part of a full examination with scans.
| Country | Approximate cost range |
|---|---|
| Turkey | €15 – €80 |
| United Kingdom | €25 – €100 |
| United States | €60 – €250 |
| Germany | €30 – €120 |
The cost of an eye test alone rarely justifies travel; people usually have refractometry as part of a package, together with corneal scans, a dilated examination or planning for surgery. What changes the price: a basic refraction or a complete assessment, cycloplegic drops, wavefront or other imaging and whether glasses are ordered afterwards. Ask the clinic what the quote covers and whether your glasses prescription is given in writing.
What happens during the refractometry test, step by step?
- History: your symptoms, current glasses or contact lenses, general health, medicines and family history of eye disease.
- Visual acuity: you read letters on a chart, with and without your current correction.
- Autorefraction and keratometry: you look at a picture inside a machine while it measures the focus of the eye and the curve of the front surface (cornea).
- Retinoscopy: the examiner shines a light and compares lenses; this is especially helpful in children.
- Subjective refraction: you look through a phoropter or trial frame and say which of two lenses looks clearer, refining sphere, cylinder and axis, then balancing the two eyes.
- Near addition: for people over about forty, the reading power is added.
- Result: the prescription is written and, if wanted, tried in trial frames so you can walk around.
The test takes about fifteen to thirty minutes, and longer if drops are needed.
When are cycloplegic drops used, and what do they feel like?
Cycloplegic refractometry uses eye drops that temporarily relax the focusing muscle and widen the pupil, so the true focusing error is measured. They are standard for children, for people suspected of squint or strong long sight, and before refractive surgery in young adults. The drops sting for a few seconds. Vision up close becomes blurred and bright light is uncomfortable for several hours, and with some drops for up to a day. Do not drive until your vision is back to normal; bring sunglasses. If you have a narrow-angle glaucoma risk or have had angle-closure, tell the examiner before drops are given. For children with misaligned eyes see our guide to strabismus surgery, where an accurate refraction is the first step.
Refractometry, corneal topography or a full eye examination: how do they differ?
| Test | What it measures | Typical limits |
|---|---|---|
| Refractometry | Focusing error and glasses prescription | Does not examine the retina or measure eye pressure |
| Corneal topography | Shape of the front of the eye | Does not give the prescription; used for lasers and keratoconus |
| Dilated eye examination | Health of the lens, retina and optic nerve | Does not itself give a prescription |
| Wavefront aberrometry | Fine optical irregularities of the eye | Specialist use; supports, not replaces, refraction |
Our guide to corneal topography explains the shape scan, and the page on eye diagnostics lists the other tests that are often done on the same day.
What do the numbers on the prescription mean?
A minus sign in the sphere column means short sight; a plus sign means long sight. Cylinder and axis describe astigmatism, where the cornea or lens is curved more in one direction. The addition is the extra power for reading. Small differences matter: a change of 0.25 dioptres is the smallest step, and most people notice a change at 0.50 or more. A prescription is not permanent; short sight often progresses in teenagers and young adults, long sight becomes more obvious with age, and the reading addition increases through the forties and fifties. Ask for a printed copy of the results, including pupil distance, so that you can order glasses anywhere.
Who benefits from refractometry in Turkey, and who should look elsewhere?
It suits visitors who want an assessment before refractive surgery, lens implants or cataract surgery, parents seeking a specialist refraction for a child with squint, and people whose symptoms do not match their glasses. If your only need is a routine glasses check and you live where optometrists are available, a local test is usually the practical choice. Persistent eye pain, sudden vision loss, flashes of light, a new shadow in the vision or double vision need an urgent medical eye examination, not a refraction test.
Is there any recovery, and how long should I stay?
There is no recovery after the test itself. After drops, blurred near vision and light sensitivity last a few hours and occasionally up to a day, so plan for no driving that day. Refractometry is normally completed within one visit, and if it is part of surgery planning you stay according to the planned procedure. Many clinics can supply glasses within a day or two, but you can also take the written prescription home.
Is refractometry safe? Risks and side effects
The test is safe and non-invasive. Drops can sting and occasionally cause redness, an allergic reaction or, in eyes with a narrow drainage angle, a rise in eye pressure after dilation, which is why a screening of the angle is done in people at risk. The larger risk is an inaccurate prescription: over-correction can cause headaches and strain, and an unrecognised eye disease can be missed if only a refraction is done. Professional bodies including the Royal College of Ophthalmologists stress that a refraction should sit within a proper eye examination.
How to choose a clinic, and what to ask
Choose a clinic with qualified optometrists or ophthalmologists, modern autorefraction and corneal imaging, a trial-frame check of the result and a willingness to give you the prescription in writing. Red flags include a firm price for glasses before any test, no examiner credentials, pressure to buy lenses or surgery and no cycloplegic testing for a child who needs it. Our page on how it works describes the process, and you can start with a free quote.
Questions to ask the clinic
- Which tests are included in the price: refraction only or a full examination?
- Will cycloplegic drops be used, and how long do they last?
- Will I receive the prescription, including pupil distance, in writing?
- Is the test part of a surgery plan, and what would that cost separately?
- Who is the examiner and what are their qualifications?
Hospitals with Eye Surgery in Turkey
Frequently asked questions
Refractometry is an eye test that measures how your eye focuses light and gives the prescription for glasses or contact lenses. It combines an automatic instrument, retinoscopy and a subjective check where you compare lens choices.
It is a well-validated measurement. Autorefraction gives a quick starting point, retinoscopy is reliable in children, and the subjective step defines the final prescription. Drops are needed for an exact reading in children and young adults.
Approximate ranges are €15 to €80 in Turkey, against about €25 to €100 in the UK. The price depends on the equipment, whether drops are used and whether it is part of a full examination.
No. It measures focusing error and the glasses prescription. A full eye examination also checks eye pressure and the health of the lens, retina and optic nerve, which refraction alone does not do.
No. The instruments do not touch the eye. Cycloplegic drops sting for a few seconds and may blur near vision and increase light sensitivity for several hours.
They temporarily relax the focusing muscle and widen the pupil, so the true focusing error is measured. They are standard for children and for suspected squint, and take a few hours to wear off.
About fifteen to thirty minutes, and longer when drops are used because you wait for them to work. The prescription is available immediately afterwards.
Most adults are advised to have an eye test every two years, children and people with diabetes more often. A change in vision, headaches or eye strain are reasons to book sooner.
Yes. An accurate refraction, together with corneal scans, decides whether laser correction is suitable and what power to treat. It is repeated before surgery to confirm the prescription is stable.
The test is done in one visit, so a short stay is enough. If it is part of planning for eye surgery or a lens implant, the stay depends on the planned procedure.