Vision & Visual Perception

Eye Movement Terminology

• Saccades: 

• Pursuits: 

• Convergence:

• Divergence:

Components of Vision

• vision: visual awareness, central vision, peripheral vision, acuity

  • Oculomotor & vision efficiency skills: pursuits, saccades, 

    • binocular fusion - eye teaming

    • depth perception

    • convergence

    • accommodation - focusing no things that change distance

    • vestibular ocular reflexes

  • Skills serve as the foundation for visual perception

• visual attention:

• visual memory:

• visual discrimination:

• object perception

  • form constancy

  • visual closure

  • figure ground

• spatial perception 

  • position in space

  • depth perception

  • topographical orientation

• visual imagery - ability to visual images in their absence

Typical Visual Development

• at birth: 20/200

• at 1 yr: 20/50

• at 2 yr: 20/20

• vision develops very late in utero

Uses of Vision in Development

• helps interpret the sensory & functional aspects of objects and the environment

• understanding the spatial relationship between self & other people/objects

• perception, visualization, & mental representations for abstract thinking

• understanding others (social cues & nuances; emotions)

• motivating

• required for learning 

Visual Impacts on Development

• developmental milestones are delayed including

  • cognition

  • communication

  • social skills

  • adaptive skills

  • gross & fine motor skills

Refractive Disorders 

• Changes with the shape of the eye

• Myopia: length of the eye is too long & child has trouble seeing items at a distance (nearsightedness)

• Hyperopia: length of the eye is too short & child has trouble seeing items up close (farsightedness)

• Astigmatism: due to elliptical curvature at the front of the eye & child has trouble with both near & far vision (blurred vision)

• Strabismus:

  • Esotropia: one eye is turned in

  • Exotropia: one eye is turned out

  • Hypotropia: one eye is turned down

  • Hypertropia: one eye is turned up

Service providers:

• each state runs their own agency to address low vision

• guaranteed services by the ADA

• MA: MCB

• CT: BESB

Evaluation

• developmental history, OP, observation

• criterion-referenced assessments (norm-referenced, standardized assessments are not normed on kids with visual deficits)

  • Hooper Visual Organization Test

• vision efficiency screening (depends on the degree of VI)

• visual perceptual/visual-motor skills (depends on the degree of VI)

• sensory processing & modulation

• interviews with O&M, TVI, developmental optometrist, MD, parent, other school staff

Intervention (Infant/Toddler)

• expand play repertoire

• social interaction

• functional mobility

• sensory processing

• feeding

• positioning

• in addition to medical interventions/developmental optometrist interventions

  • glasses

  • prism glasses - for misalignment of the eyes, bending the direction of the light coming into the eye

  • patching to avoid suppression

Intervention (Children/Youth)

• can focus on the use of residual vision and/or compensatory strategies to enhance participation

• self-care

• organization of materials/belongings

• sensory processing & modulation (including tactile discrimination)

• social participation

• motor acquisition/learning

• visual perception & visual motor skills

• development of skills for use of adaptive materials & specialized equipment

• environmental modifications & adaptations

• adaptive materials/aids - cane use, Braille