DESCRIPTION

Cataract is the term used for any opacification of the crystalline lens of the eye.

EPIDEMIOLOGY

• The prevalence of childhood cataracts is 1 to 15:10,000, with the range being attributable to reporting, definition, age, and variance in populations.
• Approximately four children per million total population will be born with bilateral congenital cataracts in developed countries.
• Adjusted cumulative incidence is 2.5 per 10,000 in the 1st year of life, increasing to 3.5 per 10,000 by age 15 years.

ETIOLOGY

• Congenital or developmental: About 2/3 of early-onset cataracts are idiopathic, the remainder being inherited or associated with systemic disorders.
• Hereditary: Autosomal dominant transmission is responsible for 75% of bilateral hereditary cataracts. Most affected individuals are otherwise healthy.
  • Phenotypically identical cataracts can occur with mutations at different genetic loci, and phenotypically variable cataracts can be found within a single family.
  • Multiple contributing genetic loci have been identified.
  • Rare hereditary syndromes combine cataracts with systemic disease. These are listed in the following discussion.
• Acquired
  • Iatrogenic: chronic steroid use or radiation exposure
  • Traumatic: blunt or penetrating ocular trauma
  • Inflammatory: chronic uveitis
• Ocular abnormalities: Cataracts may be associated with primary ocular abnormalities such as aniridia, congenital corneal opacity (Peters anomaly), coloboma, and microcornea.

GENERAL PREVENTION

• There is currently no proven way to prevent congenital or infantile-onset cataracts.
  • Timely prenatal diagnosis and treatment of intrauterine infections may lessen or prevent associated infant morbidities, including secondary cataracts.
  • Correcting an underlying metabolic abnormality and minimizing exposure to inciting agents also reduces risk.
• It is essential that all newborns (and all children) receive screening eye examinations by health care providers. In much of the world, early diagnosis and referral is still the limiting factor for a child’s ultimate visual prognosis.

PATHOPHYSIOLOGY

• Cataracts result from a derangement of the normal developmental growth of the crystalline fibers of the central lens nucleus or the peripheral lens cortex. The location of the opacity often suggests the congenital or early acquired onset.
• Childhood-onset cataracts are frequently classified according to morphology or etiology.
• Dense central opacities of ≥3 mm are considered visually significant and may produce visual disability.

COMMONLY ASSOCIATED CONDITIONS

• Prenatal factors: intrauterine infection, fetal alcohol syndrome
• Metabolic and endocrine:
  • Galactosemia
  • Neonatal hypoglycemia
  • Hypoparathyroidism
  • Diabetes mellitus
  • Homocystinuria
  • Fabry disease
  • Wilson disease
  • Mannosidosis
• Chromosomal:
  • Trisomy 21 (Down syndrome), 18, 13, or 15
  • Turner syndrome
• Dermatologic:
  • Congenital ichthyosis
  • Hereditary ectodermal dysplasia
  • Infantile poikiloderma
  • Gorlin syndrome
• Renal:
  • Lowe syndrome
  • Alport syndromes
• Musculoskeletal:
  • Marfan syndrome
  • Conradi syndrome
  • Albright syndrome
  • Myotonic dystrophy
• Rheumatologic:
  • Juvenile idiopathic arthritis
  • Other uveitis (psoriatic, HLA-B27, etc.)
• Other:
  • Craniofacial and mandibulofacial syndromes
  • Neurofibromatosis
  • Cerebrotendinous xanthomatosis
  • Long-term use of systemic glucocorticoids and ivacaftor