The crystalline lens is a lens that together with the cornea belong to the optical system of the eye. The purpose of this system is to focus the images onto the retina and thus initiate the visual process. One of the fundamental properties of the lens is its transparency.
The loss of transparency of the lens, by a partial or total opacity, is called a cataract. The most frequent cataracts are those that occur with age due to a degenerative process of the lens, although they can also be present in the first months of life or even from birth. These are called congenital cataracts. Congenital cataracts represent one of the most important causes of visual deterioration in childhood. Even today, they constitute a significant challenge for the ophthalmologist since the difficulty of their treatment lies not only in the surgery itself, but also in the rehabilitation of vision that has been limited while it was developing.
The incidence of childhood cataract has been estimated between 1 to 3 of every 10,000 children born in industrialized countries, reaching up to 15 out of every 10,000 children born in developing countries. Cataracts are the most frequent cause of treatable blindness in childhood and we could estimate 200,000 blind children per cataract in the world. Congenital cataracts can be bilateral or unilateral, the latter having a more difficult rehabilitation because the visual system prioritizes the development of vision of the eye that has no problem in front of the eye that has suffered a temporary deprivation. The eye with congenital cataract, once operated, must follow an exhaustive rehabilitation regime to avoid amblyopia, which we commonly know as "lazy eye".
A third of them are of hereditary or of family origin while in approximately 50% of cases the cause cannot be determined. The rest are due to other causes: Intrauterine infections, such as rubella, metabolic diseases, some chromosomal disorders, other congenital eye disorders, etc.
The most important consequence of cataracts in general is the decrease in visual acuity. While in adults it is the patient himself who realizes his problem, in young children, on the contrary, cataracts can go unnoticed, especially if they are unilateral since the child when seeing with the other eye may not express no symptoms. This causes a delay in diagnosis and an increased risk of amblyopia. The most frequent symptoms that can make us suspect the presence of congenital cataracts are: the leukocoria (white reflection of the pupil), nystagmus (oscillating rhythmic movements of the eyes that denote a low visual acuity), strabismus (deviation of the eyes) and photophobia (abnormal light discomfort). These symptoms will alert the parents and/or the pediatrician who will refer the child to the ophthalmologist to make an adequate diagnosis and eventual treatment.
Surgery and rehabilitation
The prognosis regarding the recovery of visual acuity will depend on the degree of cataract, the precocity of the surgical treatment and the postoperative rehabilitation. The treatment of congenital cataract is surgical and involves the extraction of the cataract and the implant of an intraocular lens that will recover the transparency of the ocular optic system. This surgery poses a series of added difficulties with respect to adult surgery due to the characteristics of the eye in childhood and also regarding the choice of the intraocular lens to be implanted since it is an eye in the growth phase whose refraction will change with time. As important as the surgical treatment is postoperative rehabilitation that will consist in the adequate correction with glasses or contact lenses of a possible residual ametropia, as well as the treatment of amblyopia for the recovery of visual acuity.