Assessment and management of strabismus conquest 10 feb 2011

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Assessment and management of strabismus conquest 10 feb 2011

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

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