University of Edinburgh
 

Prematurity and Vision

Friday 3 March 2006

Dr Lyn Cresswell, Consultant Community Paediatrician
NHS Lothian

Functional Visual Assessment

  • Severe Visual Impairment
  • Vision Development - Anatomy
  • Vision Development - Physiology
  • Vision Development - Behaviour
  • Functional Visual Assessment

Severe Visual Impairment

  • Incidence 1 in 1000 - 1 in 2500;
  • High risk population < 32 week gestation < 1500g;
  • Scottish LBW study (<1750g) 1% blind 20-30% visual problems including refractive errors;
  • 30-40 MDVI with additional disability.

Vision Development - Anatomy

  • Retina complete at 4 m;
  • LGB neurons complete at 6 m;
  • Cortex neurons complete at 4 m then reduce;
  • Myelination most at 15 m but continues till adulthood.

Vision Development – Physiology

  • Fixing and Following 3m
  • Accomodation 6m
  • Convergence 4m
  • VEP visual evoked potential 4m
  • Colour retina birth
  • Colour cortical 3m

Vision development – Visual Acuity

  • Visual acuity VA 6/120 2m
  • VA 6/24 6m
  • VA 6/18 1 yr
  • VA 6/6 3yr

Vision development - Behaviour

  • Neonate blink to flash/turn to light
  • 6 weeks F&F 45 degrees of midline/watches adult
  • 3m hand regard
  • 4m convergence/watches adult at 1.5 m
  • 6m fixates smartie at 0.3m
  • 9m fixates static ball at 3m
  • 12m fixates static ball at 6m

Visual Assessment History

  • Visual behaviour – distance/near
  • Viewing objects/postures
  • Facial recognition
  • Depth perception - stairs/kerbs
  • Crowding-locating objects in a busy environment
  • Visual attention

Visual Assessment

  • Distance visual acuity - ability to discriminate between two adjacent points
  • Near visual acuity - print size
  • Visual field
  • Colour vision
  • Contrast
  • Visual perceptual skills - visual processing
  • Visuomotor skills

Visual Acuity

  • Ability to distinguish between 2 adjacent points
  • Clarity of vision
  • Angle subtended by 1 minute of arc
  • Normal vision is 6/6

Functional Vision Assessment

  • Eye movements
  • Depth perception
  • Visual attention
  • Crowding (complex visual material)
  • Stereoscopic vision
  • 2D/3D object recognition
  • Visual discrimination
  • Visual perception/visuomotor skills
  • Reynell Zinkin Developmental Scales for Young VI children

Visual Perceptual/Visuomotor Assessment

  • Embedded Figure test (>5 yr)
  • Ravens matrices (>5 yr)
  • Morrison Gardner non motor visual-perceptual skills
  • Facial recognition
  • Figure copying
  • Block design

CP 27.10.96

  • Infantile seizure encephalopathy
  • Global developmental delay
  • Severe cerebral visual impairment

Joint Visual Assessment

  • History from classroom staff – vision has improved and CP is noted to respond better in quieter environments.
  • Visual Acuity 6/120 Cardiff Acuity Cards – response not consistent.
  • Visual Field – no response to white ball or toys coming from side.
  • Functional VA – stills to noisy toys, responds by turning towards large objects at 8-10cm, does not look directly at objects when viewing them.