18 March 2019 Author : Rita Gama The entire visual system , which includes the eyeball and brain structures, is formed at birth. During the first years of life, profound developments and transformations take place that give rise to human vision. Why does vision screening for children need to be carried out so early? Despite increasing evidence that the transformation process can continue throughout adolescence and youth, it is generally acknowledged that the principal changes occur before the child is 10 years old. Any small incident that occurs prior to this age, such as eye disease, even when it is temporary, can affect development , leading to irreversible injury if it is not treated in time. After 10 years of age, the visual system behaves in the same way as for an adult , and there is practically no risk of vision being reduced as a result of eye disease. A typical example is the response to cataract removal surgery. Where an adult will recover full vision after such surgery, in a child the loss of transparency resulting from the cataract affects the development of the visual system, leading to a reduction in vision that is often impossible to reverse. The decreased vision, which remains even after treatment of the eye disease that caused it, is known as amblyopia or “lazy eye”. Amblyopia has other causes such as strabismus (being “cross eyed”), because the brain can no longer superimpose the images of each eye and erases one of them (suppression). Refractive errors such as hypermetropia (long sightedness), myopia (short sightedness) and astigmatism (which are not considered eye diseases) can also cause amblyopia if they are not corrected. In brief, amblyopia is a disease in which the eyes appear to be normal, but in fact cannot see . This is why it’ is so difficult to detect. When should ophthalmological screening be carried out in children? Screening of all children is recommended at three intervals during childhood: Before the age of 6 months; At 3 years of age; At 5 years of age. These tests should be carried out by an ophthalmologist or a orthoptic technician - a professional qualified to work in this area. If the results of the tests are perfect, there will be no need to see an eye specialist. Screening should not replace the ophthalmology appointment if there are any doubts or if performance in the tests is lower than expected for age. How is eye disease detected in vision screening for children? In children, there are 3 ways in which eye disease manifests itself: Leukocoria: the pupil appears white instead of the usual black colour; Strabismus: loss of eye alignment or ocular deviation; Amblyopia: the vision of the two eyes is 6/10 or less, or the difference between the two eyes is 2/10 or more. Leukocoria or strabismus with marked deviations are usually noticed by the child’s parents. Strabismus with a small degree of deviation or amblyopia , on the other hand, is more difficult to identify. In this context, ophthalmological screening is of valuable assistance in detecting these conditions , which can go unnoticed by parents and children. What tests are carried out during ophthalmological screening? At a minimum, the following tests should be carried out as part of ophthalmological screening : Assessment of the macroscopic appearance of the eyes; Visual acuity scale adapted to the child's age (quantification of vision, usually on a scale of 1-10); Eye alignment (a test where each eye is covered in turn and the deviation is measured); Binocular vision: test for stereopsis, in which the visual ability to see objects in 3 dimensions is assessed. What are the warning signs? At any time, and regardless of scheduled screening tests, children who display any of the following signs should be referred to a paediatric ophthalmologist : Leukocoria (white pupil); Strabismus: before 6 months of age - if it occurs for most of the time that the child is awake. After 6 months of age - if there is constant or intermittent ocular deviation or incorrect head posture when the child looks at a point in the distance; Any reduction in the vision of one or both eyes; Family history of eye disease. It should be noted that the adoption of incorrect posture when observing things that are close is not regarded as a warning sign. What is the role of ophthalmological screening for children in detecting and treating eye disease? The period for treating childhood eye diseases ends at 10 years of age. The sooner the disease or refractive error is detected, the easier it will be to treat and the better the final outcome will be. Screening is a powerful tool in the detection of these changes , which are often silent and cause irreversible harm to visual development. As such, they should be extended to the entire child population. An eye test performed by an optician is not enough to rule out eye disease or a refractive error. Don't forget - it’s the ophthalmologist who really knows about your child’s visual health. At the hospitals and clinics of the Hospital da Luz network, there are ophthalmological specialists who can diagnose and treat eye diseases and carry out the examinations you need. Meet the ophthalmology team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
