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Assessment and management of strabismus conquest 10 feb 2011
 

Assessment and management of strabismus conquest 10 feb 2011

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    Assessment and management of strabismus conquest 10 feb 2011 Assessment and management of strabismus conquest 10 feb 2011 Presentation Transcript

    • Assessment and Management of Strabismus Fiona Crotty Head Orthoptist East Sussex Hospitals
    • Overview
      • Development of Visual Acuity
      • Assessment of Vision in Infants & children
      • What is BSV and how does it develop?
      • Classification of squint
      • Assessment of squint
      • Management of squint
    • Development of Visual Acuity
      • Dependent upon normal anatomical and physiological development
      • Eye relatively well developed in full-term infant
        • Shorter axial length (more hypermetropic)
        • Shallow anterior chamber
        • Poorly differentiated fovea (complete by 4 months age)
        • Accommodation 90% accurate by 2 – 3 months
    • Development of Visual acuity (VEP’s) * Tested with single optotypes Age Visual Acuity Newborn 6/240 1 month 6/180 – 6/90 4 -6 months 6/18 – 6/6 3 years 6/6*
    • Assessment of Vision Birth to 12 months – forced choice preferential looking
    • Assessment of vision 12 months – 2 years Cardiff Cards
    • Assessment of Vision - Cardiff Cards
    • Assessment of Vision – occluding glasses
    • Assessment of Vision 2 – 4 years Kay Pictures
    • Assessment of Vision 4 – 6 years Crowded logMAR
    • Assessment of Vision – LogMAR vs. Snellens Type
      • Snellens:
        • Traditional method
        • 6 metre test distance
        • Recorded as fraction e.g.6/60, 6/9
        • Inconsistent numbers & spacing of letters per row
      • logMAR:
        • Decimal value, 0.0 =6/6 equivalent, 0.2 = 6/9.5 etc
        • Equal number of letters per row, consistent spacing
        • Greater range of acuity values & can be used at 3m
        • Preferred method for research and amblyopia testing
    • Assessment of Vision
      • Snellens Chart
      • logMAR Chart
    • What is BSV?
      • Definition of Binocular Single Vision (BSV)
        • The ability to use both eyes simultaneously so that each eye contributes to a common single perception
      • 3 levels
        • Simultaneous perception ( 2 images seen)
        • Fusion (Interpreting 2 images as one)
        • Stereopsis (3-D appreciation)
    • Development of BSV
      • Newborn reflexes present – essential for BSV development
      • Require continued use and normal visual experience
        • Postural reflexes: static (head position to body) and stato-kinetic (head relative to space)
        • Fixation reflexes: fixation (foveal) and re-fixation (target to target and maintained to moving object)
    • Development of BSV
      • Most neonates show coarse re-fixation
      • Conjugate fixation 1 st to develop (eyes follow object together)
      • Disjugate fixation (follow approaching object – convergence)
      • Fusional reflex (correct for change in image position)
      • Kinetic reflex (controlled accommodation & convergence)
    • Development of BSV
      • From aet 4/52 Attempts at convergence seen
      • 5-6/52 conjugate fixing and brief following – neonatal misalignment common
      • 4/12 saccadic eye movements develop, neonatal misalignments reduce
      • 6/12 – 8/12 normal BSV established
    • Risk Factors for Development of Squint
      • Prematurity
      • Neuro-developmental delay
      • Motor control disorders eg cerebral palsy
      • Refractive error, failure to emmetropise
      • Family history
    • (Brief) Classification of Squint
      • Manifest (Heterotropia)
        • Esotropia (convergent)
        • Exotropia (divergent)
        • Vertical
        • Unilateral or alternating
        • Constant or intermittent (in Primary position, or in certain positions of gaze)
        • Accommodative
    • (Brief) Classification of Squint
      • Latent (Heterophoria)
        • Esophoria
        • Exophoria
        • Vertical ‘phoria
        • Fully compensated
        • Poorly compensated
    • Left Esotropia
    • Cover Test, Esotropia (1 & 2)
    • Pseudo Esotropia
    • Right Exotropia
    • Cover Test, Alternating exotropia (3)
    • Intermittent Squint Brown’s Syndrome
    • Intermittent Squint Duane’s Syndrome
    • Cover Test, Esophoria (4)
    • Cover Test, Exophoria (5)
    • Assessment of squint
      • Visual Acuity
      • Cover Test
      • Ocular Movements
      • Convergence
      • Fusion/Stereopsis?
      • Measurement of angle (prisms)
    • Management of Squint
      • Orthoptic assessment
      • Cycloplegic refraction & fundoscopy
        • Correct significant refractive error
        • Allow for refractive adaptation (up to 18/52)
        • Occlusion treatment for amblyopia (patches, atropine)
        • Orthoptic exercises (intermittent deviations)
        • Surgery
    • Summary
      • Early intermittent neonatal misalignment common between birth and 2-4 months
      • BSV well established from 6 months
      • Sensitive period for development of vision and binocular reflexes
      • Suspected squint after 4 months (corrected) age should be referred for Orthoptic assessment
    • Acknowledgements
      • Thank you to Manuel Saldana for his kind permission to use the video clips
    • Thank you