BASICS

DESCRIPTION

The World Health Organization’s classification defines blindness as corrected visual acuity of <20/200 in the better eye or visual field ≤10 degrees around the central fixation.

EPIDEMIOLOGY

Incidence

• 0.3/1000 under 5 years old in the USA and Canada (1)

• Globally 0.8/1000 under 5 years old

• Considerable regional variations are present due to the difference in biological, environmental, and socioeconomic factors.

Prevalence

• In 2000, it was estimated worldwide that 1.4 million children were blind (2,3).

• Worldwide, underprivileged societies have higher prevalence of childhood blindness.

RISK FACTORS

• Poverty

• Prenatal:

– Family history of hereditary eye diseases

– Maternal infection during pregnancy (rubella, toxoplasmosis, CMV, HSV, and syphilis)

– Prenatal drug use

– Premature birth (one of the major causes in developed countries)

• Perinatal and neonatal:

– Hypoxia/ischemia

– Infection

– Nonaccidental trauma

• Childhood:

– Nutrition: Vitamin A deficiency

– Infection

– Trauma: nonaccidental and accidental

– Systemic and neurological diseases

Genetics

Genetic eye disease and the ocular manifestations of systemic genetic disease are one of the leading causes of childhood blindness.

GENERAL PREVENTION

• Public health education on preventable childhood eye disease. Worldwide 50% of childhood blindness is avoidable (4).

• Genetic counseling for families with known genetic eye diseases

• Prenatal care:

– Maternal nutrition and infectious disease immunization and monitoring

– Avoid exposure to teratogens

– Decrease premature birth rate

– Prenatal ultrasound for congenital ocular anomalies (5)

• Perinatal and neonatal:

– Neonatal prophylactic topical antibiotics

– Early diagnosis and management of retinopathy of prematurity

– Early diagnosis and treatment of cataract and glaucoma

• Childhood: Trauma and infectious disease prevention

PATHOPHYSIOLOGY

Blindness results both from the organic disruption of the visual system (including eye and brain) from congenital anomaly or disease and from deprivation of visual development (amblyopia) and potentially from cortical visual impairment.

ETIOLOGY

• Whole globe: Microphthalmia, anophthalmia

• Glaucoma

• Cornea:

– Congenital opacities

– Scarring due to infectious disease and vitamin A deficiency is a major cause in underdeveloped countries.

• Lens:

– Cataract

– Ectopia lentis

• Uvea:

– Aniridia

– Uveitis

– Coloboma

• Retina:

– Retinopathy of prematurity

– Retinal dystrophy

– Oculocutaneous albinism

– Retinoblastoma

– Macular hypoplasia

– Retinal detachment or dysplasia

• Optic nerve:

– Hypoplasia

– Atrophy

– Neuropathy

• Cortical:

– Anatomical anomalies

– Infection

– Neurodegenerative diseases

– Hypoxic–ischemic encephalopathy

– Tumor

– Trauma: Accidental of nonaccidental

• Other: Nystagmus, high refractive error

COMMONLY ASSOCIATED CONDITIONS

• Infectious diseases: Rubella, toxoplasmosis, cytomegalovirus, herpes, syphilis

• Congenital anterior segment anomalies, glaucoma and cataract in syndromes

• Retinal dystrophy associated with syndromes

• Optic nerve anomalies associated with midline facial and brain anomalies

• Metabolic, storage diseases and neurologic diseases may be associated with blindness.

DIAGNOSIS

HISTORY

• Family history of infancy blindness and congenital ocular disease

• Maternal prenatal exposure to infection or teratogen

• Birth history

• Other known associated anomalies or developmental delay

PHYSICAL EXAM

• Ocular signs in infant:

– Constant deviation of one eye

– Nystagmus

– Wandering eye movements

– Lack of response to familiar faces

– Staring at bright lights

– Eye poking/gouging (oculodigital sign)

– Absence of dampening on vestibular induced nystagmus

– Absence of eye-popping reflex of infancy

• Systemic examination for anomalies and infections (toxoplasmosis, rubella, CMV, HSV, congenital syphilis)

• Ocular findings:

– Corneal opacity, abnormal size

– Lens opacity

– Retinal findings:

– Macular scars: Toxoplasmosis

– Macular hypoplasia: Albinism, aniridia

– Coloboma

– Retinopathy of prematurity

– Optic nerve hypoplasia, congenital optic atrophy, and other anomalies

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Based on suspected etiology

Imaging

• Consider brain MRI in cases of blindness due to optic nerve anomalies or in the absence of ocular disease that explains visual loss.

• Ultrasound to assess ocular anatomy in cases of media opacity.

Diagnostic Procedures/Other

• Examination under anesthesia as needed

• Electrophysiology testing in cases of blindness without significant ocular finding or if retinal pathology suspected

Pathological Findings

Depends on cause of blindness

DIFFERENTIAL DIAGNOSIS

• Delayed visual maturation

• Developmental delay

• Functional/hysterical visual loss

TREATMENT

MEDICATION

As appropriate for underlying disorder

ADDITIONAL TREATMENT

General Measures

• Correct refractive error

• Amblyopia treatment

• Safety glasses if poorly seeing eye <20/60

• Low vision intervention including low vision aids, mobility training, and individualized education plan

Issues for Referral

• Genetic counseling

• Consult infectious disease specialists for blindness due to infectious etiology

• Consult pediatric/genetic specialist when blindness is associated with systemic diseases

SURGERY/OTHER PROCEDURES

• Cataract extraction

• Glaucoma surgery

• Retinopathy of prematurity treatment: Laser or vitreoretinal surgery

• Strabismus surgery

IN-PATIENT CONSIDERATIONS

Admission Criteria

Admission only indicated if underlying disease warrants

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• Close cooperation with neonatologists, geneticist, pediatricians, and school

• Ongoing low vision and educational assessment

Patient Monitoring

• Annual eye exam to monitor the condition and the child/family progress and adaptation. More frequent if it is indicated

• Provide information and recommendation for social service and school.

PATIENT EDUCATION

• Genetic counseling

• Low vision intervention

• Family support network – National Federation of the Blind (NFB) (http://www.nfb.org), American Council of the Blind (ACB) (http://www.acb.org/resources/parents.html), and National Association for Parents with Visual Impairments (http://www.spedex.com/napvi/)

PROGNOSIS

Depends on etiology and access to treatment/intervention

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