Childhood Visual Impairment

Reduced visual function in a child that interferes with development, learning and daily life even with the best correction. It encompasses low vision (acuity worse than 6/18 to light perception) and blindness (acuity below 3/60 or field below 10 degrees).

• Global prevalence: about 1 to 2 per 1000 children in high income countries, up to 1.5 per 1000 in low income countries.
• Causes:
  • Cerebral visual impairment (leading cause in high income settings): perinatal hypoxia, prematurity with periventricular leukomalacia, hydrocephalus, infection, trauma, epilepsy, genetic disorders.
  • Ocular and anterior pathway: retinopathy of prematurity, congenital cataract, congenital glaucoma, optic nerve hypoplasia, albinism, retinal dystrophies (Leber congenital amaurosis, achromatopsia, congenital stationary night blindness, retinitis pigmentosa), coloboma, aniridia, microphthalmia and anophthalmia, uncorrected refractive error, corneal scarring (measles, vitamin A deficiency, harmful traditional eye medicines, ophthalmia neonatorum).
  • Nutritional: vitamin A deficiency (xerophthalmia).
  • Infectious: congenital rubella, toxoplasmosis, cytomegalovirus, syphilis, onchocerciasis, trachoma.
  • Tumours: retinoblastoma, optic pathway glioma, craniopharyngioma.

• Infants: no fixation or following by 6 to 8 weeks, roving eye movements, nystagmus, photophobia or light gazing, eye poking and pressing, lack of social smile and eye contact, delayed motor milestones.
• Older children: poor classroom performance, difficulty reading the board, holding objects near, avoiding the dark, bumping into things, crowding phenomenon.
• Cerebral visual impairment: preserved ocular examination but inattention to visual stimuli, preference for colour and movement, visual field defects (inferior), difficulty with crowded scenes and faces, visual attention fluctuation, light sensitivity, and associated cerebral palsy, epilepsy and learning impairment.
• Associated disabilities in more than 50 percent: hearing loss, intellectual impairment, cerebral palsy, epilepsy; psychological effects.

• Full assessment: history including birth, development, family history, and consanguinity.
• Functional vision: acuity (preferential looking, Cardiff cards, Lea symbols), fixation and following, contrast sensitivity, visual fields (confrontation, kinetic perimetry), colour vision, stereopsis; developmental assessment.
• Eye examination: cycloplegic refraction, slit lamp, dilated fundus examination (optic nerve hypoplasia, macular hypoplasia in albinism, retinal dystrophy), optical coherence tomography in older infants.
• Electrophysiology: electroretinogram (retinal dystrophy, Leber congenital amaurosis), visual evoked potentials (optic nerve and cortical function).
• Neuroimaging: MRI brain (periventricular leukomalacia, optic pathway hypoplasia, septo optic dysplasia, hydrocephalus).
• Genetic testing (panel testing for inherited retinal disease, albinism, anophthalmia) and metabolic screening, endocrine assessment (cortisol, thyroid, growth hormone) in optic nerve hypoplasia due to risk of hypopituitarism.
• Vitamin A level in children from endemic settings.

• Treat the cause: cataract surgery, glaucoma surgery, retinopathy of prematurity treatment, correction of refractive error, treatment of amblyopia, anticonvulsants for epilepsy.
• Optical and low vision aids: spectacles, magnifiers (hand and stand), telescopes, electronic magnification, large print, high contrast materials, tinted lenses for photophobia, and good lighting.
• Early intervention services: visual stimulation, habilitation, parent guidance, orientation and mobility training, Braille where needed, assistive technology (screen readers, text-to-speech), inclusive education with a teacher of the visually impaired.
• Cerebral visual impairment: simplify the visual environment, reduce crowding, use movement and colour, give extra time, position materials in the best field.
• Vitamin A for xerophthalmia: 200,000 IU orally on days 1, 2 and 14 (100,000 IU for age 6 to 12 months, 50,000 IU under 6 months) with dietary support; immunisation (measles).
• Endocrine replacement for hypopituitarism (hydrocortisone, levothyroxine, growth hormone) when present.
• Genetic counselling for inherited disease; gene therapy (voretigene neparvovec for RPE65 mutation) where available.
• Registration or certification of visual impairment, social support, psychological support, and transition planning for adolescents.