Age and Vision

At birth it used to be thought that babies were virtually blind. However, science has now caught up with what most parents already knew and we are now aware that babies can perceive most large, high contrast objects and have detailed acuity (level of vision) approximately 1/10th of adult levels. At birth the two eyes do not necessarily work together but by 3 months of age a baby should be able to fix and follow an object.

By 6 months vision is approaching 50 – 60% of adult levels with acuity and colour discrimination improving. If by this stage there is any doubt that the eyes are working together and looking in the same direction then professional advice should be sought. Notice should be taken of the pupils that should be of equal size, round in shape and black in colour. The time between birth and 8 years of age is known as the critical period of visual development. During this time, visual acuity develops rapidly, reaching adult levels.

Anything that interferes with the development of either eye during the critical period can lead to amblyopia (lazy eye) - where the amblyopic eye achieves poorer acuity than the ‘good’ eye. Causes of amblyopia include a squint (eye turning inwards or outwards), congenital abnormalities such as congenital cataract, or one eye having a significantly different spectacle prescription to the other – in this case, the weaker eye will be amblyopic. Children with an amblyopic eye will not develop good binocular (3D) vision, since the brain needs a clear image from each eye to use both images together.

If amblyopia is diagnosed early enough, it can be treated to try and make the amblyopic eye ‘work’ and develop normally. This can be achieved either by prescribing spectacles or using a patch over the good eye; this is usually done under the supervision of an orthoptist. The earlier this treatment is started, the greater the chances of a successful outcome, therefore it is essential that all children have at least one eye examination before they start school to ensure that both eyes are developing normally and equally. If all is well at this examination, we usually recommend seeing children annually.

If there is a family history of squint or amblyopia, or parents have noticed a squint or suspect that vision is not developing normally, an eye examination is recommended as soon as possible.

Kay Pictures

Cardiff Cards - a preferrential looking test

Eye examinations for children are funded by the NHS. We do not need children to be able to read letters to have an eye examination – there are various letter and picture matching tests available that can give an accurate assessment of vision.

Between the ages of 8 and the late teens, vision is still developing and it is often at this age that children can become myopic. During study and working life, uncorrected low spectacle prescriptions that may not have previously caused problems can lead to eyestrain.

From the age of 40 onwards, there is an increased risk of developing eye conditions such as glaucoma. This risk increases over the age of 60, with many people developing cataract and the risk of developing macular degeneration. For this reason, regular eye examinations are advised. Eye examinations are available on the NHS for those over 60.