A cataract is a medical condition where the normally clear lens of the eye becomes cloudy, similar to looking through a frosted or dirty window. The lens, situated behind the iris, is responsible for focusing light onto the retina. When its proteins break down and clump together, vision becomes blurry and colors appear faded. While most people associate cataracts with aging, finding this clouding in an infant, child, or adolescent is unusual. Early-onset cataracts signal an underlying genetic, metabolic, or acquired problem that interferes with the lens’s development or maintenance.
Causes Present at Birth (Congenital Cataracts)
Cataracts present at birth or developing within the first year of life are classified as congenital. Genetic factors are a major contributor, with a family history present in approximately one-fifth of cases. These inherited forms often involve a faulty gene that disrupts the proper formation of lens fibers during fetal development.
Chromosomal abnormalities and genetic syndromes, such as Down syndrome, frequently include cataracts as an associated feature. Also, certain infections contracted by the mother during pregnancy can cross the placenta and damage the developing lens tissue. Key infections include Rubella, Toxoplasmosis, Cytomegalovirus (CMV), and Herpes Simplex Virus, which are part of a group known as the TORCHES complex.
Metabolic disorders are another significant cause, involving the body’s inability to process certain chemicals correctly. For instance, Galactosemia is an inherited condition where the body cannot effectively break down the sugar galactose found in milk. This leads to a buildup of toxic byproducts in the lens, causing osmotic stress and protein damage. This results in the rapid formation of an oil-droplet-like cataract that requires immediate dietary intervention to prevent progression.
Causes Related to External Factors and Intervention
Cataracts can be acquired later in childhood or adolescence due to acute external events or as a complication of necessary medical treatments. Ocular trauma is a frequent cause, resulting from a direct blow to the eye or a penetrating injury. Physical force disrupts the delicate arrangement of the lens fibers and capsule, allowing fluid to enter and cause the lens to swell and become opaque.
The clouding may appear immediately after the injury or progress slowly over months or years. Another well-established cause is the long-term, high-dose use of corticosteroid medications, which are often prescribed to manage severe inflammatory conditions. These drugs, whether taken orally, inhaled, or applied topically as eye drops, accelerate the formation of a posterior subcapsular cataract.
Exposure to certain types of radiation can also induce lens changes. High-energy ionizing radiation, such as X-rays used in cancer therapy near the head, can damage the DNA of the lens cells. Similarly, chronic and excessive exposure to ultraviolet (UV) light, particularly the UVB spectrum, can contribute to protein aggregation in the lens.
Causes Stemming from Underlying Systemic Health Issues
Chronic health conditions that affect the entire body can promote cataract formation in young people. Diabetes Mellitus, particularly Type 1, is a prominent example where poor blood sugar control is directly linked to lens damage. High blood glucose levels cause excess sugar to enter the lens cells, where it is converted into sorbitol, a sugar alcohol the lens cannot easily remove.
The buildup of sorbitol draws water into the cells, creating osmotic stress that disrupts the lens structure and causes swelling and clouding, often leading to a “snowflake” appearance. Chronic inflammation within the eye, known as uveitis, frequently causes cataracts as a complication. Uveitis can occur alone or be associated with systemic diseases like Juvenile Idiopathic Arthritis (JIA).
The persistent presence of inflammatory chemicals compromises the lens’s nutritional supply and integrity. Furthermore, treating severe uveitis often involves the long-term use of high-dose topical corticosteroids, which also contribute to cataract formation. A specific link exists between severe Atopic Dermatitis (eczema), a chronic skin condition, and the development of an “atopic cataract.”
While the exact mechanism is complex, this link is believed to involve chronic eye rubbing, inflammation, and potential nutritional deficiencies. Finally, several rare genetic syndromes that affect connective tissue or metabolism, such as Marfan syndrome, also increase the risk of early-onset cataracts. These systemic causes highlight that the lens, though small, is highly sensitive to disruptions in the body’s overall internal balance.