Cataracts in Children

Overview

Definition

A cataract is a painless opacity of the lens that disrupts the light projecting onto the retina, resulting in a clouding of vision. Cataracts can cause partial or total blindness.

Epidemiology

• Prevalence: 
  • 1–15 per 10,000 children
  • Higher in low-income countries
• Around 15% of pediatric blindness is due to cataracts.
• ⅓ are inherited cases, another ⅓ are due to systemic diseases, and the rest are idiopathic.

Anatomy

Lens:

• Part of the eye’s refractive media
• Transparent structure made of fibers
  • Lens fibers:
    • Cortex: outer part; made up of younger fibers
    • Nucleus: deep part; made up of older fibers
  • Lens epithelium: between fibers and anterior capsule 
  • Lens capsule: outermost layer (anterior and posterior)
• Essential for proper visual development (which occurs from birth to 8 years of age)

Etiology and Pathophysiology

Cataracts by age of onset

• Congenital/infantile
  • Onset at birth
  • Recognition of cataract at a later age does not exclude congenital onset. 
• Acquired/juvenile
  • Onset in childhood (after infancy)

Cataracts by etiology

• Genetic:
  • Mutations in genes that code for the lens structure
  • Most are autosomal dominant.
• Disease-associated: 
  • Ocular conditions:
    • Uveitis
    • Retinopathy of prematurity
    • Persistent fetal vasculature
  • Galactose metabolism disorders
    • Classic galactosemia (“oil droplet” cataract) and galactokinase deficiency
    • Galactose is processed by aldose reductase to galactitol in the lens.
    • ↑ galactose → ↑ galactitol → ↑ osmolarity and fluid accumulation in the lens → cataracts
  • Dermatologic syndromes
    • Congenital ichthyosis 
    • Ectodermal dysplasia
  • Endocrine disease:
    • Diabetes mellitus
    • Hypoparathyroidism
  • Chromosomal anomalies:
    • Trisomies: 13, 18, and 21
    • Turner’s syndrome
  • Intrauterine infection:
    • TORCH (Toxoplasmosis, Other agents, Rubella, Cytomegalovirus, Herpes simplex)
    • Other: syphilis, varicella zoster, parvovirus B19
  • Other syndromes:
    • Marfan’s syndrome
    • Alport’s syndrome
    • Neurofibromatosis type 2
    • Myotonic dystrophy
• Iatrogenic:
  • Corticosteroids (systemic)
  • Radiation:
    • Cataractogenic dose (minimum): 500 rad
    • Cranial radiation: eye shield required and children undergo yearly eye exam
  • Vitrectomy: Children who have undergone the procedure have a risk of mostly posterior subcapsular cataract.
  • Laser treatment: When used for retinopathy of prematurity, thermal injury increases the risk of cataract.
• Ocular trauma:
  • Direct trauma (perforation or blunt injury)
    • More common in boys
    • During play or sports-related activity
  • Electric shock
    • Exposure to high-voltage current/lightning

Clinical Presentation

• Parental complaint:
  • Child not following object close to face 
  • Not making eye contact (e.g., unable to recognize their mother)
  • Television viewing at close distance
• Clinical features:
  • Asymmetric red reflex: noted on exam and old photographs
  • Leukocoria
    • White pupillary reflex
    • Pupil is “white” rather than black.
  • Decreased vision and developmental delay
    • Child does not have usual expected visual behavior at age.
    • Learning impaired (child cannot read the blackboard)
  • Nystagmus
    • Poor visual prognosis
    • Develops by 2–3 months in congenital cataracts
  • Strabismus
    • Abnormal alignment of the eyes; squinting
    • Associated with poor visual outcome
  • Photophobia: scattering of light by the cataract
  • Other features: Extraocular symptoms depend on the presence of systemic illness or syndrome(s).

Diagnosis

Initial assessment

• History: review patient and family risk factors

• Vision risk assessment at all health maintenance visits
• Vision screening if with risk factors (family history of congenital cataracts, retinoblastoma, metabolic or genetic disorders)
• Red reflex: most sensitive method to detect cataract
• Visual acuity:
  • Photoscreener or autorefractor beginning at 12 months of age
  • Use age-appropriate visual assessment tools:
    • Fix and follow (up to 3 years of age)
    • Cover test
    • Snellen chart or other optotype

Ophthalmologic examination

• Funduscopy and slit-lamp examination
• Performed by a pediatric ophthalmologist (may require sedation)
• Different parts of lens affected
• Morphology and location can give clues to the underlying pathology:
  • Diffuse/total (entire lens): after trauma
  • Anterior: anterior polar (often hereditary, especially if bilateral)
  • Central: fetal nuclear (central-most part of the lens); associated with microphthalmia 
  • Posterior: 
    • Posterior subcapsular (area anterior to the capsule): usually acquired cataract (glucocorticoid, radiation, injury)
    • Posterior: persistent fetal vasculature (blood supply to the lens did not disappear before birth)

Other tests

• Ocular ultrasound: occasionally needed to check posterior segment of the eye
• If indicated:
  • Metabolic: blood and urine tests for specific disorder(s)
  • TORCH titers for suspected congenital infection
  • Genetic testing

Management

Considerations

• Age:
  • Increasing age means increased visual demand.
  • Earlier onset of cataract and denser opacification: ↑ risk of amblyopia
  • Unilateral congenital cataract: Optimal age of surgery is by 4–6 weeks.
  • Bilateral congenital cataracts: Optimal age of surgery is by 8 weeks (at most, 1 week apart).
• Visual function and development: 
  • Refractive changes occur as the child grows.
  • Once lens removal is done, loss of accommodation occurs.
  • If intraocular lens (IOL) is not placed: bifocals needed to optimize near and distance vision

Conservative management

• Indications:
  • Visual acuity better than 20/50
  • Opacity < 3 mm in diameter or of partial density
  • No visual behavior problems
•  Components of treatment:
  • Refractive errors: Use contact lenses or corrective glasses. 
  • Occlusive therapy: patching eye with better vision
  • Monitoring of progression

Cataract extraction

• Should be performed by an experienced pediatric ophthalmologist
• Indications:
  • Opacity of > 3 mm
  • Reduced visual acuity (20/50 or worse)
  • Decreased quality of life from visual impairment
  • Onset of strabismus or nystagmus
• Procedure involves:
  • Removal of lens
  • Anterior vitrectomy and posterior capsulectomy (with or without IOL placement)
  • IOL not recommended in children < 1 year of age
• Surgery complications:
  • Secondary cataract
  • Glaucoma
  • Strabismus
  • IOL malposition
  • Retinal detachment
  • Endophthalmitis (infection within eye; rare)

Differential Diagnosis

• Uveitis: an acute inflammation of the uvea (middle layer of the eyeball) and of the ciliary body. Uveitis can be caused by infections (toxoplasmosis, toxocariasis) or can be related to systemic inflammatory disease (rheumatoid arthritis). Symptoms include blurry vision, red eye with pain (anterior uveitis) or without pain (intermediate and posterior uveitis), and visual floaters (intermediate uveitis).
• Retinoblastoma: the most common intraocular malignancy in childhood, usually diagnosed before the age of 5. Retinoblastoma frequently presents as an abnormal white reflection from the retina, called leukocoria. Other features include red eye, strabismus, and nystagmus. Ophthalmoscopic examination reveals a retinal mass. Additional imaging studies including ocular ultrasound can be used for diagnosis.
• Retinal detachment: separation of the retina from the retinal pigment epithelium resulting in rapid photoreceptor damage. In children, this may be from trauma, retinopathy of prematurity (ROP), or retinal dysplasia syndromes. Retinopathy of prematurity causes leukocoria in the setting of retinal detachment.
• Coloboma of the optic disc: a congenital abnormality due to a defect that occurs in the embryonic development of the optic nerve. The condition has a hereditary component. Coloboma of the optic disc appears as a hollowed-out optic disc and can present as leukocoria on examination.
• Retinopathy of prematurity: abnormal vascularization of the retina that occurs in premature infants. Injuries from hypotension or hyper- or hypoxia are believed to contribute to the disruption of normal retinal vessel growth. Neovascularization occurs and can cause fibrosis and retinal detachment. Leukocoria is seen in later stages of ROP.