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.