Paediatric Ophthalmic Studies (Visual Evoked Potentials and Electro-Retinography)

Patient Leaflets Team

  • Reference Number: HEY-789/2016
  • Departments: Neurophysiology


This leaflet has been produced to give you general information about the tests your child will be having done.  Most of your questions should be answered by this leaflet.  It is not intended to replace the discussion between you/your child and their doctor, but may act as a starting point for discussion.  If after reading it you have concerns or require further information, please discuss this with a member of the healthcare team caring for your child.

What are ophthalmic studies?

These are tests measuring electrical responses from various points of your child’s eye and brain to a variety of visual stimuli. These include the optic nerve, retina and macula.

Why does my child need ophthalmic studies?

Ophthalmic studies can help to diagnose a range of problems affecting the eye or visual pathways. They can help the doctors see how the different parts of your child’s eye are functioning and obtain the correct diagnosis.

Can there be any complications or risks?

For older children the procedure may involve placing a small thread across the surface of the eye and applying anaesthetic and dilating eye drops. Very occasionally this may cause slight soreness and reddening of the eyes.

The anaesthetic used will temporarily numb the surface of the eye and the dilator may make the eyes more sensitive to light. We therefore advise your child to wear sunglasses for a few hours until the effects of the drops have worn off.
The dilating drops may distort vision for up to 4 hours so activities involving motorised equipment must be avoided during this period.

Very young children may not be able to sit still or co-operate well enough for the examination. If this happens the physiologist will discuss other options with you.

How do I prepare my child for the ophthalmic studies?

Please read this information leaflet. Share the information it contains with your partner and family (if you wish) so that they can be of help and support. There may be information they need to know, especially if they are taking care of your child following this examination.

  • Please ensure your child’s hair is freshly clean and dry with no spray/gel etc on it.
  • Please ensure your child is not wearing eye makeup/mascara etc.
  • If your child wears glasses please bring them with you. Contact lenses cannot be worn for some of the testing so glasses are needed if your child has them.
  • Please do not bring any other children with you as we are unable to accommodate them in the clinic rooms or supervise them in the waiting area.

What will happen?

The actual procedures undertaken will vary depending upon the age of your child and their ability to co-operate. The physiologist will discuss this with you prior to commencing the tests.

Very young children will have their head measured and a few small disks attached to their head with paste. We will then patch one eye and show your child a flashing light. This is then repeated with the other eye. Further sticky pads will be attached to your child’s face around the eye and they will again be shown the flashing light. This can take between 30–45 minutes dependent on the child.

For older children, the physiologist will first check your child’s vision. If they wear glasses please bring them with you.

Your child’s head will be measured and some small metal discs applied with paste.

Your child will then be asked to look at a screen with moving black and white squares. Each eye will be tested separately. This test is totally painless and there are no after effects. The test can take a maximum of 45 minutes.
Following this, further testing will be done, which involves placing a fine thread across the surface of their eye and asking them to watch the same screen. This will be explained in more detail on the day and anaesthetic drops can be placed in your child’s eye so they do not feel the threads. This part of the examination takes about 30 minutes.

The final part of the examination can take a maximum of 50 minutes. The threads remain in the eye and drops are applied to dilate the pupil. Please inform us if your child suffers from glaucoma. Your child will then sit in front of a machine and place their chin on a chin rest and look into a dome which will deliver a flash of light. This may happen a few times and we will then sit your child in the dark for 30 minutes. You will be able to sit with your child during this period. We will then show your child some more flashes of light at different intensities.

Towards the end of the test your child will be asked to sit for 10 minutes in bright light before being shown a final few flashes of light.

The physiologist will then remove the threads and disks from your child’s eyes and face.

What happens afterwards?

Following the testing the paste will be removed from your child’s hair with cotton wool and warm water.

The results will be sent to your child’s referring doctor, usually within 2 weeks.

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact the Neurophysiology Department on tel: (01482) 675339 or 675388.

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats your child, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to your child. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your child’s condition, the alternatives available for your child, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about your child

We collect and use your child’s information to provide your child with care and treatment. As part of your child’s care, information about your child will be shared between members of a healthcare team, some of whom you may not meet. Your child’s information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide your child with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your child’s doctor, or the person caring for your child.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about your child. For further information visit the following page: Confidential Information about You.

If you need information about your child’s (or a child you care for) health and wellbeing and their care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.

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