A congenital cataract refers to a clouding of the eye’s natural lens that is present at birth or develops during early childhood. This condition interferes with the passage of light to the retina, potentially affecting visual development. Unlike cataracts that typically form in older adults due to aging, congenital cataracts arise from different underlying reasons.
Causes of Congenital Cataracts
Congenital cataracts can stem from various origins, with some cases having no identifiable cause. Genetic factors are a primary category, where specific gene mutations, often inherited, can disrupt normal lens development. Syndromes like Down syndrome, Lowe syndrome, or neurofibromatosis type 2 are also associated with an increased incidence of congenital cataracts.
Infections acquired by the mother during pregnancy can also lead to congenital cataracts in the fetus. Rubella, or German measles, is an example where the virus crosses the placenta and affects fetal eye development. Other infectious agents, such as cytomegalovirus (CMV), toxoplasmosis, herpes simplex virus, and varicella (chickenpox), have also been linked to cataract formation in newborns.
Metabolic disorders constitute another group of causes, where the body’s inability to process certain substances properly can lead to lens opacification. Galactosemia, a condition where the body cannot process galactose (a sugar found in milk), can cause cataracts if left untreated. Other metabolic conditions can similarly disrupt the biochemical balance required for a clear lens. Despite these known causes, a considerable percentage of congenital cataracts, estimated to be between 30% and 50%, are classified as idiopathic, meaning their specific origin remains unknown.
Identifying Symptoms and Diagnosis
The most commonly observed symptom of a congenital cataract is leukocoria, which appears as a white or grayish-white pupil instead of the typical black. This unusual reflection is often noticed by parents in photographs, particularly when a flash is used, or through direct observation. Other visual signs may include nystagmus, characterized by rapid, involuntary eye movements, indicating poor visual fixation. An infant might also display a lack of visual attention or an inability to track objects, suggesting impaired vision.
Formal diagnosis often begins with the red reflex test, a routine part of newborn screening examinations performed by pediatricians. During this test, a light is shined into the infant’s eyes, and a healthy red-orange reflection from the retina is expected. The presence of a cataract will disrupt this reflection, appearing as a dark spot or an absent red reflex, prompting further investigation. If the red reflex is abnormal, the infant is referred to a pediatric ophthalmologist for a comprehensive eye examination.
A specialized ophthalmological examination involves dilating the pupils for a detailed view of the lens and the back of the eye. The ophthalmologist uses an ophthalmoscope or slit lamp to assess the size, location, and density of the cataract. This evaluation helps determine the extent of visual obstruction and guides decisions regarding intervention.
Surgical Removal of the Cataract
Surgical removal is the primary treatment for congenital cataracts, often performed early in an infant’s life to facilitate proper visual development. The timing of surgery is a key factor, with procedures for significant cataracts often scheduled within the first few weeks to months after birth. Early intervention is important because prolonged visual deprivation can permanently impair the development of visual pathways in the brain. The precise timing depends on the cataract’s density and location, and whether one or both eyes are affected.
The surgical procedure involves removing the clouded natural lens, known as lensectomy or cataract extraction. During the operation, a small incision is made in the eye, and specialized instruments are used to break up and remove the opaque lens material. In very young infants, an intraocular lens (IOL) is typically not implanted at the time of initial surgery, especially for those under six months of age. This approach is taken because the eye is still growing rapidly, and an implanted lens’s power would need frequent adjustment.
For infants where an IOL is not placed during initial surgery, the eye becomes aphakic, meaning it lacks a natural lens and its focusing power. Removing the physical obstruction allows light to reach the retina. The eye’s ability to focus light onto the retina is then managed with external corrective lenses, an important aspect of post-surgical care.
Vision Development After Surgery
Removing the cataract is the initial step in a comprehensive visual rehabilitation process for infants. After surgery, the eye, now lacking its natural lens, requires external optical correction to focus images sharply onto the retina. This is typically achieved through specialized infant contact lenses, which are custom-fitted and provide the necessary refractive power. In some cases, thick glasses may be prescribed, particularly if contact lens wear is challenging or not suitable. Consistent and appropriate optical correction is essential for clear image formation and healthy visual pathway development.
A primary concern following congenital cataract surgery is the development of amblyopia, commonly known as “lazy eye.” Amblyopia occurs when the brain favors the stronger eye and suppresses visual input from the weaker eye, leading to underdeveloped vision in the affected eye. This condition can arise even after the cataract has been removed if the brain does not receive clear, consistent visual input from the operated eye. Early and sustained treatment for amblyopia is a standard part of post-surgical care.
Patching therapy is a common and effective method used to treat amblyopia. This involves covering the stronger, non-operated eye for several hours each day, forcing the brain to rely on and strengthen vision in the eye that underwent cataract surgery. The duration and frequency of patching are carefully monitored by an ophthalmologist, often continuing for several years as the child’s visual system matures. Regular follow-up appointments are also important to adjust corrective lenses, monitor for complications, and assess visual progress.