Congenital Cataract

Mark Brookes


Cataract describes clouding of the lens which leads to scattering of light. Lens abnormality accounts for up to 20% of paediatric blindness globally and congenital cataract affects around 2 per 10,000 births (1). The term congenital cataract is often used synonymously with infantile cataract, despite the former more strictly referring to cataract present at birth as opposed to present within the first year of life.


Lens transparency is achieved thanks to regular lens fibre cell and extracellular matrix arrangement, presence of intracellular proteins and tightly controlled water and solute microcirculations (2). Any condition which affects proper development of these factors may lead to lens opacification. Identification and treatment of lens opacity in young children is important to avoid amblyopia. In most cases of both unilateral and bilateral congenital cataract the cause is not easily identifiable. However, bilateral cataract is more likely than unilateral cataract to be associated with underlying chromosomal aberration, intrauterine infection or metabolic disorder.

Cataract in young children may be identified at routine screening, or not infrequently by a parent noticing leukocoria (3). Congenital cataract is bilateral in the majority of cases (4), and in around half of these cases there is an associated systemic or ocular disorder. The most common of these are Down syndrome and intrauterine infection. Where there is an associated ocular disorder in unilateral cataract, the most common is persistent fetal vasculature (5).

Genetic disorders

Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18) are screened for in pregnancy with a blood test. Both can be diagnosed with amniocentesis or chorionic villus sampling.

In Down syndrome, infants may develop symmetrical cataracts alongside other ocular features including myopia, keratoconus and Brushfield spots of the iris.

Edwards syndrome can cause cataract, coloboma of the uveal tract and optic disc, microphthalmos and ptosis.

Cataract is near ubiquitous in Nance-Horan syndrome, an X-linked condition associated with craniofacial anomalies and intellectual disability. The cataract may take the form of an opaque Y-suture (6). Most patients with X-linked Hallermann-Streiff syndrome also have cataract and micropthalmia.

Intrauterine infection

Among other infective conditions, a TORCH screen tests for toxoplasmosis, rubella, cytomegalovirus (CMV) and herpes infection, all of which can cause cataract.

Toxoplasmosis is caused by the protozoan Toxoplasma gondii. It is typically transmitted via the faeco-oral route from cats to humans, but primary infection in a pregnant woman can lead to transplacental spread. Congenital toxoplasmosis infection is less severe later in pregnancy and

apart from cataract, it can cause uveitis, vitritis, optic disc oedema, neuroretinitis and microphthalmia.

Rubella may also cause uveitis, retinopathy and microphthalmia. If the ocular abnormalities are associated with sensorineural hearing defect and cardiac defects, the child has congenital rubella syndrome (7).

Congenital CMV infection may cause jaundice in the child and hepatosplenomegaly, with more severe cases exhibiting microcephaly and intracranial calcifications. Ocular manifestations include keratitis and chorioretinitis.

Pregnant women are screened for chickenpox history at booking and may need varicella zoster virus (VZV) serology if without a history and becoming newly exposed during pregnancy.

Congenital VZV syndrome includes limb hypoplasia and sensorimotor deficit. Development of the optic stalk and lens vesicle is impaired, leading to microphthalmia, cataract and optic atrophy.

Metabolic disorders

Patients with congenital cataract may also be tested for metabolic disorders.

Lowe syndrome, or oculocerebrorenal syndrome, almost always presents with cataract as well as renal and neurological abnormalities (8). Inheritance is X-linked recessive and heterozygous females may have insignificant lens opacity. In patients with the disease, cataract are typically bilateral and dense. The disease can be detected with urinary protein and amino acid testing and can be diagnosed with genetic testing.

Fabry disease is also X-linked recessive in inheritance. In this condition related to tissue glycolipid accumulation, corneal opacities typically develop before lens opacities. Non-ocular features include cardiac and renal defects, angiokeratoma and acroparesthesia. Fabry cataract is typically posteriorly sited and wedge or spoke-like in nature.

A patient with cataract secondary to galactosemia may avoid development of significant cataract if galactose is withheld from the diet early in life. This autosomal recessive condition is fatal if untreated so testing urinary reducing sugars is important if suspected. Characteristically, the cataract has an ‘oil droplet’ appearance.

Mannosidosis is also autosomal recessive in inheritance. The cataract is more typically posterior and spoke-like. Conditions associated with abnormal glucose levels or with hypocalcaemia (such as hypoparathyroidism, particularly linked to posterior subcapsular cataract) should also be considered as these states can precipitate cataract formation.

Persistent fetal vasculature (PFV)

Presence of PFV is typically sporadic rather than inherited and may be associated with a cataract. The cataract in these cases is typically progressive and may cause a shallow anterior chamber with glaucoma. PFV may also be associated with microphthalmia.

Clinical assessment

Careful examination, often with a portable slit lamp, is important to fully assess the cataract. The patient should be assessed for other causes of leukocoria. In general, the larger and more dense the lens opacity, the greater its effect on normal visual development.

The most common type of congenital cataract is lamellar (9), with a characteristic central nucleus and a surrounding opacified nuclear layer. Other types include nuclear, cortical, anterior/posterior polar, posterior lentoconus and posterior subcapsular.

Anterior polar cataract is usually small and does not typically reduce best corrected visual acuity but may lead to anisometropia. Therefore, it can still predispose to amblyopia. A variant form of anterior polar cataract is anterior pyramidal which may be larger and protrude into the anterior chamber (10). Posterior polar cataract is particularly associated with PFV.

Posterior lentoconus describes a posterior cone-shaped protrusion of the lens surface. Its location may predispose to posterior capsule rupture and opacification. It may exhibit an oil droplet appearance but is best identified using ultrasound biomicroscopy.

Congenital posterior subcapsular cataracts are usually bilateral and may be associated with systemic disease such as neurofibromatosis type 2.

A more severe cataract will preclude adequate fundoscopy. Structures posterior to the lens should be assessed with B-scan ultrasound, and appopriate referral arranged if it is thought likely that an underlying condition is present.


In general, surgery should be performed sooner in denser cataract to prevent amblyopia. A unilateral cataract, if visually significant, should be even more urgently prioritised. In these cases, the target is surgery by age 6-8 weeks (11). If both eyes have dense opacity, the more severe cataract is removed first, and usually by 10 weeks of age (12). A partial or mild unilateral cataract does not necessarily require early surgery but should be monitored throughout childhood.

Surgical management usually involves posterior capsulorhexis because postoperative posterior capsular opacification is extremely common. Anterior vitrectomy may be performed alongside this (13). Uveitis, if not properly managed postoperatively, may lead to formation of secondary membranes. Glaucoma is more common in children who have undergone cataract surgery (14). The rate is particularly high in patients under 4 weeks old.

Given a higher complication rate and similar visual acuity outcomes with early IOL insertion, some centres suggest leaving infants under 7 months’ old aphakic (15). Younger aphakic patients therefore need refractive error correction postoperatively. This requires glasses or contact lenses in patients who have undergone bilateral lensectomy. Contact lenses are preferable in unilateral aphakia to avoid aniseikonia. When IOL insertion is performed, the overall refractive error target is hypermetropia as this should gradually trend towards emmetropia with age.

Follow up

Paediatric cataract surgery has a higher complication rate and lower visual outcome when compared to adult. Patients may still develop amblyopia and strabismus. In fact, almost all

patients with unilateral cataract will end up with both complications, whether receiving surgical treatment or not.

The child should be seen the day after surgery, and then several times over the following 4 weeks. Topical combination antibiotic and steroid is often used over this time period. At follow up, retinoscopy is important to establish appropriate refractive error correction. Similarly, IOP measurements are important to monitor for development of ocular hypertension. Orthoptic assessment should also continue throughout childhood to detect strabismus and amblyopia early (16).


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