University of Edinburgh
 

The Assessment of Visual Functions in Children with Visual Impairment

Presented on Saturday, 11 December 2010

The Changing Face of Paediatric Visual Impairment

Prof A J Jackson PhD, MCOptom, FAAO, FBCLA

Global Childhood Blindness and Low Vision (1)

  • 1 million blind in Asia
  • 300,000 blind in Africa
  • 50% of children die within 2 years of onset of blindness
  • 500,000 new cases of childhood blindness occur every year
  • 98% of blind children don’t have access to education

Global Childhood Blindness and Low Vision (2)
Principal Causes

  • Corneal Scarring (Vit A Def, Measles) 500,000
  • Cataract 200,000
  • Retinal pathology (ROP) 300,000
  • Glaucoma 100,000
  • Others 200,000

Gilbert 1993, Foster 1988

Global Childhood Visual Impairment
Principal causes vary according to location

Europe & USA:

  • 40-50% genetic
  • 20-30% perinatal

Asia (Middle East):

  • 70-90% genetic

Africa:

  • 50-80% infective

kratoconus

Pedigree of the kindred with keratoconus with cataract showing alleles of marker loci
Dash, Silvestri, Frazer, Willoughy et al

Childhood Visual Impairment (NI)

Of 354,000 school age children 0-15 yrs (population 1.7m), 761 are known to receive specialist educational services for visual impairment.

  1. Specialist school for visually impaired (Jordanstown) (53)
  2. Support services for mainstream schooling (613)
  3. Support services of children with complex needs (148)

Only 221 children are, however, registered as blind or partially sighted. Services provided by 10 Peripatetic Teachers

Community Based Survey NI (1)

Of 47,110 children in East Belfast, age <19 years, 76 were identified using triangulation methodology (n=6) as having significant visual problems (1.61 per 1000) (Mean age 10.5 ± 4.8 years / M:F ratio 6:7)

  • 68% exhibited developmental abnormality
  • 21% mild to moderate learning disability
  • 43% global delay with severe learning disability

Other Associations

  • Cerebral Palsy 33% (n=25)
  • Co-Existing congenital abnormality (heart defect) 41% (n=31)
  • Behavioural difficulties 11%

Flanagan et al, 2003

Community Based Survey NI (2)

survey

In 33 cases, near acuities were recordable N5-N6 = 11; Only 17 were registered (11 blind/6 partially sighted); Only 2 were Braille users.

Community Based Survey NI (3)

survey

Community Based Survey NI (4)

  • Of those with CVI (34), 12% were totally blind, 26% had PL and 62% had low vision.
  • Only 2 were registered Blind or Partially Sighted.
  • Only 18% of CVI children used LVAs.
  • 76% attended schools for children with learning disability.
  • All of these children had other complex problems : CP (21), Epilepsy (19), Hydrocephalus (11), Hearing impairment (8)

History of Educational Services for those with Visual Impairment in the UK

  • 1791 - First UK school for the indigent blind (Liverpool)
  • 1793 - Asylum for the industrious blind (Edinburgh)
  • 1870 - 12 educational establishments for the blind (UK)
  • 1872 - Foster Education Act - Elementary Education for All Royal Commission - Compulsory education for the blind aged 5-16 years
  • 1909 - Sight saving classes for myopes
  • 1934 - Blind and PS children were being educated in 55 schools for VI (UK)
  • 1941 - Certification of defective children
  • 1972 - Vernon Report: residual vision
  • 1978 - Warnock Report: integration
  • 1986 - Educational statementing

Educational Developments NI (Jordanstown)

  • 1831 Congregational Church School for the Deaf: Belfast, King's Street
  • 1836 The Ulster Institute for the Deaf, Dumb & Blind: Belfast, College Street
  • 1845 Transfer to purpose built school: Belfast, Lisburn Road (75 pupils/23 Blind)
  • 1920 Blind Persons Act Provision of state funding for Education of the Blind
  • 1941 Evacuation to Donaghadee
  • 1945 Return to the Lisburn Road, Belfast
  • 1961 The move to Jordanstown
  • 2009 New Build-Potential for Regional, National cooperation

Jordanstown School Attendance 1980 - 2000

school attendance

Jordanstown School Current Educational Profile 2001/2002

  • Currently 53 pupils (32 VI / 21 HI)
  • Primary Department 17 Children
  • Secondary Department 36 Children
  • 45 Sighted Methods/ 3 Braille or Moon Users/ 2 Other Non-Sighted Methods
  • Between 1831 and 1931 those educated included 1300 HI pupils and 500 VI pupils

Primary Ophthalmic Diagnosis Jordanstown School 1980 - 2000

ophthalmic diagnoses

Distance & Near Visual Acuities Jordanstown School 1980 – 2000 (n = 254)

visual acuities

Conclusions

  • The proportion of children attending Jordanstown school, with Albinism has increased consistently over a 20 year period.
  • The proportion of children attending Jordanstown School with cataracts has decreased significantly over a 20 year period.
  • There has been a recent trend towards a reduction in the numbers of children attending the Primary Education Dept of Jordanstown.
  • There has been no significant change in the visual status of children attending Jordanstown School over the last 20 years.
  • Eighty percent of those with usable vision have near acuities correctable to N10 or better.
  • Only 11% of the current student population use non-sighted educational methods.
  • Optimal Low Vision care of children in a specialist school for the VI involves providing Appliances and Aids appropriate for the task.

Low Vision Aids

A Low Vision Aid is any device which can be used to optimise residual vision once refractive error has been corrected with spectacles or contact lenses.

Paediatric Low Vision Hardware

Optical Aids

  • Hand Magnifiers
  • Stand Magnifiers
  • Spectacle Magnifiers
  • Near Vision Telescopes
  • Distance Telescopes

Non Optical Aids

  • CCTVS etc
  • Large Print etc
  • Lighting (Task Specific)
  • Tactile Materials
  • Audio Materials

Computer Technology can supplement most things.

Biometrics of Refractive Error in CP

Refractive errors more common & correlate with axial length (r 0.91)

refractive errors

Refractive errors not due to unique ocular growth profile in CP.

Low Contrast acuity in CP

low contrast acuity

Notes: Dashed lines are normative CS data (Vistech) from Larrson et al (2006) 10 year old kids - blue line are full term controls and purple line premature children. Black solid line are mean data from 35 subjects in CP study (6-19 years old) showing shift in CS curve related to poorer VA and generally poorer CS. 

Children with Albinism (NINA)

children with albinism

Case Scenarios

Four cases which collectively illustrate the essence of paediatric/childrens Low Vision Services