Severe visual impairment in 1/1000 births. 50% of severe visual impairment is genetic:
• Identify causes amenable to treatment (e.g. congenital cataracts).
• Use non-visual stimulation (e.g. touch, speech) to aid development.
• Provide a safe environment.
A child is registered blind when the best-corrected vision is less than 3/60. The criterion for partial sight registration is a visual acuity better than 3/60, but less than 6/60.
• Trisomy 21.
• CHARGE association.
• Retinal dystrophy.
• Congenital infection, e.g. CMV, rubella.
• Retinopathy of prematurity.
• Hypoxic ischaemic encephalopathy.
• Cerebral damage.
• Optic nerve hypoplasia.
• Infection, e.g. ophthalmic herpes simplex.
• Juvenile idiopathic arthritis: iritis.
Babies with delayed visual maturation (DVM) appear blind in the first few months, but their visual behaviour improves with age. There are 3 forms:
• Isolated DVM: there is no underlying pathology and there is a rapid and full development of vision between 3–6mths of age. Motor development may also be delayed.
• DVM associated with cerebral visual impairment: e.g. infants with cerebral palsy may initially appear blind. The vision usually improves over years, but may be impaired.
• DVM associated with ocular disease: congenital ocular disease, e.g. cataracts, and nystagmus can interfere with early visual development. Vision improves over years, but with residual deficit.
Children with DVM should be monitored for general developmental issues. Visual impairment teachers should be involved to help parents to stimulate visual development