As the crystalline lens has been removed through cataract surgery, light will no longer focus and form an image on the retina.
Sight develops as an image is formed in the eye and transmitted to the brain. Pathways that allow the brain to process images cannot be formed if the brain is denied an image. This condition is called Amblyopia.
In a child’s life, the first year is a crucial period when pathways from the eye to the brain can be formed. After that point, it becomes hard to improve vision, although some enhancement can be made after eight years of age.
Following cataract removal, the child must have spectacles or a contact lens fitted immediately so that the visual pathway to the brain can start to form. The downside of spectacles is that they can cause image distortion, prismatic effects, and conditions called Anisometropia and Aniseikonia. All of these conditions can lead to a less than perfect image.
On the other hand, a contact lens acts as if it were part of the eye; wherever a child looks, he or she will be looking through the lens centre.
Further, spectacles are not possible in the case of unilateral (one eye) Aphakia because of the image size difference (Aniseikonia) induced. Unlike an adult aphake, a child’s eye is continuing to grow. As the eye length increases, the power needed to correct the child’s vision will decrease.
This causes frequent changes in a child’s contact lens. It is necessary to frequently examine a child’s visual development. Also, as lenses are important in stimulating vision, leaving them out for any length of time may result in vision loss.
The fit of the lens must be continually checked, in order that changes are made as the eye grows. It is believed that the use of contact lenses in paediatric Aphakia is medically essential.