Congenital cataracts

They are the presence of a cataract (opaque crystalline lens) at the time of birth. The crystalline lens is a lens that forms part of the optical system along with the cornea. The purpose of this system is to focus images in the retina. To perform this function, the cornea and crystalline lens must be transparent. The loss of the crystalline len's transparency through partial or complete opacity, is called a cataract. If you are born with an opaque crystalline lens, it is called a congenital cataract.

The main symptom of a cataract is low visual acuity. However, in young children the cataract can go unnoticed, particularly if it is unlateral as the child can see with the other eye. Symptoms that may alert parents or the paediatrician are: leukocoria (white reflex of the pupil), nystagmus (rhythmic oscillating movements that denote low vision), strabismus (deviation of the eyes) and photophobia (abnormal discomfort to light). 

The incidence of congenital cataracts is approximately 3/10,000 newborns. Two thirds are bilateral and in 50% of these cases the cause is identified. The most common aetiological factor is autosomal dominant inheritance; other possible causes include chromosomal anomalies, metabollic disorders and intrauterine infections. Unilateral cataracts are usually sporadic without any family history or systemic disease and they affect children who are otherwise healthy.  

The treatment for a congenital cataract is surgery and it involves extracting the opaque crystalline lens and implanting an intraocular lens. Dense bilateral cataracts must be operated on between 4 and 10 weeks old. Mild bilateral cataracts may not need surgery until later or may never need it. A dense unilateral cataract requires surgery more urgently as there is a risk of developing lazy eye. 

As important as the surgical treatment is the post-operative rehabilitation which involves proper correction with glasses as well as treatment for amlyopia (lazy eye) for the recovery of visual acuity.