Visual Jargon

This information will help you to put complex visual jargon and measurements into more manageable terms.

A regular eye examination is very important, however getting bogged down with technical terms can make understanding your child’s visual abilities some what difficult. Below are examples of some terminology you may have come across.  

If your child is attending the eye department at the hospital they will encounter different health care professionals at different times.  All departments work together so that your child receives the best care possible.

Vision & Learning

Having a regular eye test and an updated pair of well fitting glasses allows the child to use what vision they have to the best of their ability (See ‘Well fitting frame’).

Vision plays an important part in our lives.  This is especially true when it comes to learning.  If a child has a visual impairment this can hinder the learning process, as teaching and learning is mainly based on visual tasks.  Small steps can help make visual dependant learning easier. Optometrists, healthcare professionals, parents, and teachers must make learning as enjoyable and as easy as possible.  

Any excess effort to see will cause the child to tire more easily and will reduce the thinking power for understanding visual information. Some children’s eyes can’t work together due to different reasons such as amblyopia (lazy eye) or a strabismus (squint) so therefore their depth perception (3D vision) is reduced. 

Another common feature is nystagmus (eyes wobble), this can make fixation difficult, and reduces reading speed.   This extra effort can put increased pressure on the visual system, and subsequently on the child can tire more easily.  This is noticeable towards the end of the day; a nap during school if possible helps.  Quite often this isn’t practical and older children will need a break or a lie down in the evening before starting homework.

You may notice a head tilt or turn when a child is looking at something of interest or trying to concentrate on something visually.  This head position called ‘the null point’ which is unique to them, is adapted subconsciously and shouldn’t be corrected.  It allows the nystagmus movement to lessen and become more controlled in that particular position, thus improving their focus and vision.  Small adjustments can make reading and fixation a little easier such as

  • Placing finger on page of good / high contrast reading material,
  • Clean school black/white board free from glare and dust,
  • Closing blinds on sunny days,
  • Slanted boards for reading.
  • Preference seating (toward front of the classroom)
  • Providing a classroom assistant to help out, flag up problems, or photocopy material into larger print (ask your optometrist / GP/ Ophthalmologist or Social Services about ‘Statementing’).

Importance of a regular eye examination

Lots of useful information can be gathered during an eye test.  The optometrist will make the eye examination as fun and as interesting as possible.  Different letter and picture charts are used, and quite often little lights are shone into the eyes for an eye health and prescription check.

As discussed previously (see accommodation) from time to time drops are required to get a gold standard base line measurement of your child visual function.  The eye drops (cycloplegic drops) can sting for a few seconds, and temporarily remove the eye muscles ability to accommodate (focus) thus as parents you will notice the large pupil, and the child may report some blurred vision.  But these are only temporary and the benefits from an eye test of this kind are vast. This type of refractive eye test is necessary as children’s eyes change a lot as they are developing; but as the child grows they will need the drops instilled less and less.

It is very helpful to bring some dark sunglasses for the way home as this will make things much more comfortable until the effects wear off (12-24 hours later).


  • Vision

    How well an individual can see, without glasses/corrective lenses.

  • Visual Acuity (VA)

    How well an individual can see objects (letters/symbols) with glasses. This is measured during an eye test and is written as a figure called visual acuity (VA). The optometrist will assess what the child can see with and without glasses, often visual acuity (with glasses) is better than vision (without glasses). For example if your childs VA is 6/24; this means that the child needs to be 6 meters away from an object which you or a person with ‘normal vision’ can see at 24 metres). OR more simply if a child see’s 6/24 this means that an object needs to be 4 times larger or closer (6 divided into 24 goes 4 times, therefore 4 times larger) than something a person with ‘normal vision’ can see at an average distance. This rule can be applied to any of those 6 over figures i.e. 6/60 ..this means your child with a VA of 6/60 needs the object to be 10 x bigger or 10 x closer; than you / a person with ‘normal vision’ can see.

  • Visual Field

    The extent of space in which objects are visible to an eye in a given position i.e. if you fixate on an object in this distance without moving your eye you are still able to see the surrounding landscape. This can be reduced in some individuals to almost a tunnel vision effect (like looking through cardboard tubes). Some children can bump into objects or not open their mouth when presented with a spoon from a certain angle because they have no vision in that area. A simple visual field assessment will be performed by your optometrist or ophthalmologist.

  • Visual Impairment

    The visual acuity is still blurred / edges of objects are indistinct, or there is a loss of the visual field. Sight problems are very common, and many people are either long or short-sighted; however a visual impairment remains despite correction with glasses. Glasses can improve the vision a little, taking pressure off the visual system, and providing a clearer image. However as there may be structural changes or developmental damage to the eyes or visual pathway, the maximum level of visual acuity achieved from wearing the glasses, is not at the ‘normal/standard’ level of vision i.e. 6/6 is also known as “20:20 vision”.

  • Visual Pathway

    Light passes from the eye, through the retinal photoreceptors (rod and cone cells), along the optic nerves to the brain, were the picture is received / deciphered. This corridor is called the visual pathway. Structural complications can occur at different parts along this pathway. Various tests help us pin-point why children may not be able to see as well as we would expect.