How does a squint or the need for glasses cause a lazy eye?
When a child has a squint, the brain switches off that eye to stop the child seeing double. This is due to a child’s visual system being very pliable. The longer the eye is switched off the less the eye and the part of the brain that is responsible for vision is stimulated. This leads to a reduction in vision. The same happens for a child that needs glasses or has a cataract in one eye. Anything that blocks or distorts the visual stimulus in that eye will ultimately result in amblyopia. How do you test a young childs vision to tell if they have a lazy eye or not? Various observational tests can be used on babies and toddlers to gain an estimation of their level of vision. Once a child can talk we use a picture test to assess the vision and from around the age of 4-5 we use a letter matching test, where the child matches the letters shown by the Orthoptist on his/her card. The letters shown gradually reduce in size. Once the child can name the letters, their vision can be tested using t
