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).


  • Prescription

    The power or strength of corrective lenses / glasses. A glasses prescription can be in the form of positive (+) or negative (-) lenses, depending on whether a person is short or long-sighted. For example the prescription written below demonstrates how the right eye (RE) is short sighted needing a simple minus lens (-2.25) to correct it; where as the left eye (LE) is longsighted requiring a simple positive lens (+3.75) to correct its refractive error. The lenses used in this case are called Spheres (spherical power). If you see a number written alone (as demonstrated below) this means that the eye is either long or short sighted and has no astigmatism. Prescription (RE): -2.25 (LE): +3.75 If an individual has an astigmatic element (rugby ball curve to their cornea); their glasses prescription will be a combination of more complex lenses (both positive and / or negative lenses). This longer more complicated prescription is needed to rectify/correct the amount of astigmatism. Vision Prescription VA 6/60 (RE): +4.50 / -3.00 x 180 6/18 The above prescription is of a right eye which is long sighted with astigmatism). The numbers relate to a +4.50 Spherical power lens to correct the spherical element, and the amount of astigmatism is corrected by a -3.00 (Cylindrical or Astigmatic power) lens, the axis of which is at 180 degrees. You will see that the person’s visual acuity in the previous case was improved with the glasses prescription. This person can see 6/18 (VA: visual acuity) with the above prescription, but could only see 6/60 (vision) without. Therefore although this individual may not reach the bottom line of the chart, they have achieved a good improvement in VA with the glasses. A copy of an up to date prescription is necessary in order to get new glasses. An example of a prescription can be seen on the yellow voucher given to you by the optometrist.