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Accomodative Esotropia

Accomodative Esotropia. DR LIAM LIM RVEEH OMC JOURNAL CLUB SEPTEMBER 2007 EDITED BY LIONEL KOWAL. Types. Refractive Non refractive / Convergence Excess High AC/A Ratio (Parks) Abnormal Distance/Near Relationship DNR (Black). SEMINAL ARTICLES REVIEWED.

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Accomodative Esotropia

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  1. Accomodative Esotropia DR LIAM LIM RVEEH OMC JOURNAL CLUB SEPTEMBER 2007 EDITED BY LIONEL KOWAL

  2. Types • Refractive • Non refractive / Convergence Excess • High AC/A Ratio (Parks) • Abnormal Distance/Near Relationship DNR (Black)

  3. SEMINAL ARTICLES REVIEWED • 1. Abnormal accomodative convergence in squint (Parks 1957) • 2. Long term Study of Accomodative Esotropia (Ludwig, Parks 2003) • 3. The Influence of Refractive error Management on the Natural History and Treatment Outcomes of Accomodative Esotropia (Black, 2006)

  4. Parks (1957) • Part I Interrelationship btw AC/A ratio, onset of strabismus, degree of hyperopia • Part II Comparing treatments (5) for normalisation of AC/A ratio • Part III Increasing fusional divergence amplitude

  5. Part I • AC/A = normal vs abnormal • Abnormal = near and distance measurements ≥10 ∆ difference, with full cycloplegic correction

  6. Incidence Abnormal A:AC • 897 esotropes • 414 (46%) had abnormal A:AC ratio • 230 (26%) congenital, 667 (74%) acquired • 16% of congenital ET had abnormal AC:A • 57% of acquired ET had abnormal AC:A

  7. Degree of Hypermetropia Congenital • normal AC/A: mean +2.25D • Abnormal AC/A: mean +2.0D Acquired: • Normal AC/A : mean +4.75D (43%) • Abnormal AC/A : mean +2.25D (57%)

  8. Park’s conclusions • Amongst acquired esotropias, hyperopia and abnormal AC/A ratios are equally important in causing esotropia. • Without an abnormal AC/A ratio, a moderate amount of hyperopia is required to incite esotropia. With an abnormal AC/A ratio, a small amount is enough.

  9. Part II - Improving AC/A ratio • Time • Bifocals: only if straight in distance • Isoflurophate (DFP) [modern version: phospholine] • Orthoptics (dissociation exercises) • Surgery

  10. Results • Time (73): Spontaneous improvement rare <5y, up to 50% from 7-12y • Bifocals (151): few (19/151) improved • Isofluorophate (47): very effective in short-term. 4/15 <5yrs had lasting improvement vs 28/32 >7yrs. • Orthoptics (37): few had lasting improvement, but many converted from esotropia to esophoria. • Surgery (184): 205 operations on 184 pts. BMMR.

  11. Park’s conclusions • Time • Bifocals important in treatment, controls but doesn’t change AC/A • Isoflurophate and surgery both normalize abnormal AC/A • Isoflurophate useful especially >7yrs. • Surgery ONLY for distance ET not corrected by full cycloplegic refraction, not for correcting AC/A ratio.

  12. Part III • Fusional Divergence • Improved in about half of patients who underwent dissociation exercises • Approximately same level of success in those with decreasing regimen of isofluorophate

  13. Ludwig + Parks (2003) TAOS • “Long term study of accomodative ET.” • Large private practice. Data collected by “masked” research assistant. • Inclusion: ET<8yrs, alignment within 4∆ with spectacles, 5 year FU. • Exclusion: <1.5D anisometropia, >20/100 amblyopia, DVD, previous EOM surgery, <2 yr FU, mental retardation. • 354 pts identified out of 1307 pts.

  14. Factors associated with deterioration • Increased AC/A ratio • Von Noorden : Low AC/A ratio -> ET worsens (gradient method) • Dickey Scott: no correlation (gradient method) • Raab: 13% deteriorated with normal AC/A, 21% with high AC/A (not statistically significant) • Amblyopia • Inferior oblique overaction • Early onset of accomodative ET

  15. Black (2006) • Study Population: single private practice, pts with ET. • Inclusion: >10∆ ET, hypermetroipia, <10∆ with full cycloplegic refraction, 2 y follow up.

  16. Questions • 1) What is the natural history of hyperopia in treated accomodative esotropes? • 2) Does full correction vs undercorrection affect this natural history? • 3) What factors are associated with deterioration of accomodative ET?

  17. Treatment • All ET >+1.5D, prescribed full cycloplegic refraction • At 4-6wk review, if ANY ET, repeat cyclo refraction and prescribe any extra +. • If at any rv, child is ortho or small esophoria, no extra plus prescribed, even if cyclo ret showed more hyperopia

  18. Hyperopia and ET • Natural history of hyperopia • Up to 7: unchanged or slight increase (0.15/yr) • After 7: slight decrease (0.17D/yr) • In this study, ET did not usually resolve. • 13% resolved (37/285 pts) • In these pts, initial hyperopia was lower (mean 3.2D vs mean 4.5D) • 31 out of 37 pts were refracted within 6mths of their 7th birthday -> mean decrease in their hyperopia was 0.37D

  19. Undercorrection of hyperopia • Safe to Undercorrect? • Orthophoria and 1st FU and last FU • Least successful if abnormal distance/near relationship • Total (193) = Group 1 full (63), Group 2 <1D undercorrection (85), Group 3 >1D undercorrection (45) • Undercorrection did not cause a greater rate of decrease of hyperopia • Undercorrection did not cause a greater resolution of accomodative ET.

  20. Deterioration of Control of AET MORE LIKELY • Age at diagnosis • Oblique muscle dysfunction • Abnormal near-distance relationship LESS LIKELY • Fully accomodative ET

  21. Abnormal Distance-Near relationship • 41% had abnormal DNR on at least one visit • 23% had abnormal DNR consistently • 51 pts had abnormal DNR, but not consistent. Of these 19 (37%) had increased hyperopia. DNR normalised.

  22. Discussion • Important for prescription of full cyclo refraction and for re-refraction if residual ET at followups. • Inadequate correction leads to higher DNR and higher deterioration of ET. • Atropine may uncover further hyperopia.

  23. Discussion • 1/3 of pts cannot be undercorrected. 2/3 can - but should they? This study does not show that undercorrection affects resolution of ET, or resolution of hyperopia. Undercorrection can affect fusional control and lead to deterioration of ET.

  24. Resolution of AET • 13% in this series. (cf Raab 24.4%) • Minimal change of hyperropia in this series • Natural history of hyperropia in literature is unclear. • Flitcroft suggested decreased emmetropization in pts wearing full cyclo refraction. • Atkinson’s series : hyperopic infants randomised to glasses, no change in emmetropization.

  25. Resolution of AET Ingram: • strabismic hyperopes do not emmetropize compared to non-strabismic hyperopes. • Spectacles retard emmetropization in non-strabismic hyperopes.

  26. Early Onset AET • 21 patients: Poor stereoacuty, high rate deterioration • Baker Parks (21pts): 48% deterioration/surgery. Dickey Scott (13pts): 77% surgery. • Probable overlap btw infantile eso and early onset AET.

  27. Deterioration of AET • High DNR associated with deterioration • Ludwig&Parks: same finding • Raab: high DNR not associated • Dickey Scott: gradient AC/A not associated *high DNR, not same as high gradient AC/A (Arnoldi Shainberg)

  28. Bifocals • Most high DNRs do not need bifocals. • Pts not treated had either • Esotropia on distance, or • Esophoria/intermittent ET on near • No difference in deterioration of AET in this study. • Pratt-Johnson: no better sensory outocome. • Arnoldi & Shainberg: better control amongst patients not wearing bifocals after 5 years.

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