What happens at an eye test?

What happens in eye test

Eye tests involve a 20-30 minute series of assessments of your vision and eye health. These typically measure your visual acuity (sharpness of vision), refraction (if you require corrective lenses) and the structures at the front of your eyes. These are conducted by an ophthalmic practitioner or optometrist is a comprehensive process that typically begins with a discussion about your medical history and any vision problems you might be experiencing.

Additional tests, such as tonometry to measure eye pressure, and fundus photography or optical coherence tomography (OCT) to image your retina, may also be conducted. The eye exam concludes with a discussion of the findings and recommendations for any necessary treatments or corrective measures.

Very close view of brown human eye

What are the steps of an eye test?

#1 Preliminary consultation

Prior to your eye test, the ophthalmic practitioner or optometrist typically discusses your medical history and any visual problems you may currently be experiencing. This gives you the opportunity to mention any recent changes in your vision or eye-related symptoms such as visual floaters, dry eyes or headaches etc.


#2 Pupil dilation

Using a small torch, the optometrist will shine the light towards your pupil to access how well it can dilate. This is carried out seperatley for each pupil to ensure they are dilating correctly and to check for any conditions such as glaucoma, retinopathy or macular degeneration.


#3 Visual Acuity test

The acuity test, also known as the letter chart test, measures the sharpness of your vision. You'll be asked to read a series of letters or symbols from a Snellen chart positioned a specific distance away. By covering the opposite eye, each can be tested individually to assess your visual acuity.

Possibly the most recognisable part of your eye test, this is when the optometrist uses a phoropter or similar device to determine your eyeglass prescription. This device holds interchangeable lenses of varying dioptric strengths. The optometrist will ask you which lens power provides the clearest vision to establish any refractive correction you may/may not require.


#4 Visual field test

The visual field test is a key component of a comprehensive eye exam, used to assess the full extent of your peripheral, or 'side' vision. An optometrist will typically perform this test by moving an object or their finger from the periphery of your vision towards the centre, both horizontally and vertically, while instructing you to keep your head still and only move your eyes.

Modern versions of the visual field test utilize computer programs, which can provide a more detailed and accurate assessment. These tests are crucial for detecting any blind spots or visual field deficits which might be indicate conditions of your eyes and optic nerves.


#5 Colour vision test

Typically, this is administered early-on during an eye examination, playing a crucial role in determining your ability to recognize and distinguish between different colours. The test typically utilizes Ishihara plates, which are images composed of multicoloured dots in varying sizes and lightness against a contrasting background.

Hidden amongst these dots are numbers or patterns formed by dots of a different colour. If you have  good colour vision, you'll be able to discern these numbers or patterns amidst the colourful dots. However, if oy have colour deficiencies, such as red-green colour blindness, you may struggle or be completely unable to see the numbers.


#6 Glaucoma Test

Also known as Tonometry, the glaucoma test is a vital part of your eye examination, helping in the early detection of this potentially sight-threatening condition. In modern practices, this is carried-out with a machine that produces a small 'puff' of air directed at each of your eyes. As the air bounces back, the machine measures the pressure within the eye to detect any symptoms that indicate glaucoma. Prior to this assessment, you may be given anaesthetic eye drops (lidocaine or oxybuprocaine) to temporarily numb your eyes.


#7 Slit-lamp test

Using a tool known as a slit lamp (a high-intensity light source that can be focused to shine a thin sheet of light into each of eye), the optometrist uses this device in conjunction with a biomicroscope to examine the frontal structures of the eye, such as the cornea, iris, lens, and anterior chamber.

The test is non-invasive and totally painless. You're usually asked to rest your chin and forehead on a support to keep your head steady. With your eyes properly aligned with the device, the optometrist looks into your eyes through the eyepiece of the biomicroscope, adjusting the focus and width of the light beam for a better view of the different eye structures.

The slit-lamp test can provide valuable information about the health of these structures, and can assist in diagnosing conditions such as cataracts, macular degeneration, corneal ulcers, and more.


#8 Retinal Photography & OCT

Fundus photography is a non-invasive microscope with an attached camera used to take pictures of the interior surface of the eye, including the retina, optic disc, macula, and posterior pole (fundus). This procedure aids the optometrist in detecting and monitoring conditions such as retinal detachment, macular degeneration, and optic neuropathies.

Optical Coherence Tomography (OCT) uses light waves to take cross-sectional images of the retina, allowing the optometrist to see each of the retina's distinct layers. These layers can be mapped and measured, helping in the early detection of conditions such as glaucoma and diseases of the retina. This depiction is akin to an optical biopsy, providing a detailed look at the eye's structures without the need for surgical intervention. These tests are crucial in maintaining optimal vision health, allowing for early intervention and treatment where necessary.


#9 Optional Hearing Test

Some optometrists offer an additional/optional hearing test, which is becoming increasingly available via large-chain pharmacies and franchised opticians. This test takes about 15 additional minutes and can give a comprehensive understanding of your sensory health.


#10 Personal Eyecare Recommendation

Lastly, based on the results of your eye test, the optometrist will provide personalized eyecare advice. This includes discussing any changes in your vision, detected conditions, and the best treatment options. If glasses are required, the optometrist will assist you in choosing suitable frames and lenses.


Close view of three transparent framed eyeglasses

Do I have to buy glasses after an eye test?

No. There's no obligation for you to purchase new glasses directly after your eye test. If you're prescription has changed, it's certainly a good idea to update your lenses and/or frame. However, you're completely free to choose when and where you buy your new glasses.

Keep in mind that your eye test is a medical assessment of your vision and isn't tied to an obligatory purchase on the day of your exam. Treat these separately and you're more likely to invest in a glasses frame you'll love.


How often should I have an eye test?

At a minimum, it's advised that you have your eyes tested every two years unless our ophthalmic practitioner or optometrist suggests more frequent examinations. However, if you're experiencing any changes in your vision or have concerns about your eyes, it's important to schedule an eye exam with your optometrist as soon as possible.


How long does an eye test take?

On average, a basic eye exam takes 20-30 minutes but this can vary depending on your individual needs. If additional tests or assessments are required, your eye test may take slightly longer. Listed below are the average durations of eye tests delivered by major UK providers.

  • Specsavers: 20 mins
  • Vision Express: 25 mins
  • Boots: Up to 30 mins


What happens after an eye test?

After your eye test, you'll be provided with a copy of your prescription. Subject to any eye conditions detected during your eye test, you may also be provided with any referral documentation for further assessment. Optical vouchers may also be provided if you're eligible.


Does my optician have to give me my PD?

Opticians aren't legally required to give your PD measurement on your prescription. Most prescription papers omit this measurement, often intentionally, therefore you may need to attain this yourself manually. Luckily, measuring your pupillary/inter-pupillary distance is something your can do yourself using a basic ruler or this downloadable version.


What questions are asked at an eye test?

During an eye test, you may be asked a variety of preliminary questions designed to assess your vision and eye health. Your optometrist might ask about any recent changes in your vision, such as blurriness, seeing spots or floaters, or difficulty seeing at night.

They may also inquire about any discomfort or pain in your eyes, as well as your history of corrective eyewear usage. In addition to your eye health, your optometrist may inquire about your overall health, including whether you have any chronic conditions, like diabetes or high blood pressure, which can impact your vision.

They'll likely ask about your family's eye health history, as many vision problems are hereditary. Finally, your lifestyle habits, such as computer usage and exposure to sunlight, may also be discussed, as they can affect your visual health.


Can I wear makeup to an eye exam?

Yes, you can certainly wear makeup to an eye exam. However, for certain stages in the test, your optometrist may administer anaesthetic eye drops to temporarily numb your eyes or dilate your pupils. For mascara or eyeliner, this can be problematic causing them to smudge or run. On the day of your test, you may wish to avoid these kinds of makeup or use waterproof equivalents.


What should you avoid before an eye exam?

To give the best experience and results before an eye exam, it's best to avoid drinking excessive amounts of caffeine or alcohol. These kinds of stimulants can affect your blood pressure, making it either higher or lower than usual. Prior to your eye test, avoid heavily caffeinated beverages such as coffee or energy drinks. Equally, avoid large volumes of alcohol the night before your exam.

Things to do before an eye test

  • Get a good night's sleep
  • Be hydrated
  • Know your personal/family medical history
  • Note the names of any medications/ your currently taking
  • Take your current eyeglasses/contact lenses
  • Prepare any questions you might have


Key takeaways

  • Eye tests are carried out by a qualified ophthalmic practitioner or optometrist
  • The average time for an eye test is between 20-30 minutes.
  • An eye test involves a detailed examination of your vision and overall eye health.
  • Your optometrist will ask about your general health and lifestyle habits, as well as your family's eye health history.
  • Some eye tests offer a complementary or additional hearing test which takes about 15 minutes on average.
  • You can wear makeup to an eye exam, although it might be best to avoid mascara and eyeliner in case any eye drops are used.
  • Avoid consuming excessive amounts of caffeine or alcohol before an eye exam as they can affect your blood pressure and potentially, the results of the eye test.


Hopefully you found this article helpful. Please check out our other eyecare blogs. Thanks for stopping by.