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M. M. Parks

Surgical management of partially accommodative ET with convergence excess DR ELINA LANDA OCULAR MOTILITY RVEEH JOURNAL CLUB EDITED BY LIONEL KOWAL. Convergence excess ET – ET with D/N disparity, where the near angle exceeds the distance by more than 10∆( with or without high AC/A ratio)

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M. M. Parks

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  1. Surgical management of partially accommodative ET with convergence excessDR ELINA LANDAOCULAR MOTILITY RVEEH JOURNAL CLUBEDITED BY LIONEL KOWAL

  2. Convergence excess ET – ET with D/N disparity, where the near angle exceeds the distance by more than 10∆( with or without high AC/A ratio) • Surgical goals: 1 Alleviate symptoms 2 Reduce N deviation without altering D 3 Improve binocularity 4 Eliminate need for bifocals

  3. M. M. Parks • BMR is the best surgery resulting in AC/A ratio improvement by 66% • Standard surgery for partially accom ET was based on residual deviation for dist with full correction. 50%- rate of undercorrections • Parks suggested (1975)to add 1mm to each MR rc in pts with conv excess ET : - significant undercorrection rate - no success in eliminating the bifocals (1/3 with bf)

  4. Augmented BMR by Kushner • Augmented rc- BMR+1mm if N-D 10∆ BMR+1.5mm 15 ∆ max 6.5mm BMR+2.0mm 20 ∆ “Comparison augmented BMR with BMR & faden” Outcomes:- alignment follow up 5 years - bifocals - spectacles

  5. Kushner: Augmented BMR 15y outcome • 22/25 were available • 86% good alignment: 27% alignment +correction for alignment 36% with correction for VA 23% w/o correction • 3/22 unsatisfactory results: 1/3- recurrent ET 2/3 XT

  6. Augmented BMR by Wright for ET with high hypermetropia • Pt: Dsc 40ET; Nsc 50E Dcc 20ET; Ncc 30ET • Standard Dsc+Dcc/2 25pd • Augmented Nsc+Ncc/2 40pd • Refr b/w +3 to +9 • Conv excess 10/30 SG 12/40 AG

  7. Kushner: should you overcorrect and cut the plus?

  8. Augmented BMR using the Prism Adaptation Test • The preoperative use of prisms to determine the max angle and estimate fusional potential • 60% - prism responders 50% - St BMR 50% Aug BMR • Alignment within 8pd 79% 72% nonresp 89% • Long-term (3y) results (Rosenbaum) Alignment 76% PA sx vs 31% non PA sx

  9. PAT in convergence excess ET • Kutschke -65 pts with conv excess ET 31 sx for near PAT 34 for dist PAT 95% alignment 86% alignment 0 – need in bf 2/3 – bf Overcorrection – 9%

  10. PAT in convergence excess ET • Kraft – 65pts 83% responders 17% non- responders 72% align.+fusion 55% align. + fusion 76% alignment 73% alignment Unsuccessful 13pts 9 undercorrections 4 overcorrections

  11. Strabismus surgery for elimination of bifocals • 16pts 13/16 PAT+ 3/16 PAT- 10/13 – 1 surgery 1/13 – 1 surgery 2/13 cons XT 2/13 – cons XT 1/13 rec ET • Surgery is based on PAT for near angle

  12. Faden operation • Aim of faden is to weaken the EOM only in its field of action, not affecting ocular alignment in primary gaze • Peterseim and Buckly : 95%- norm. AC/A 70% - good motor and sensory fusion for near • Vivian : 95% success in decrease of near deviation and stereo

  13. Posterior fixation sutures- permanent suturing of muscle belly to sclera near the equator • A. Scott (The fadenoperation: mechanical effects. Am Orthopt J 1977) suggested a mechanical explanation: -moving the effective insertion to the equator results in torque reduction ( b/c of shortening of muscle’s lever arm for rotation of the globe) • J Demer (Posterior fixation sutures: a revised mechanical explanation… Am J Ophthal 1999): suggested an explanation based on rectus muscle pulleys: main mechanism - mechanical restriction of movement through the pulley

  14. Modifications to the fadenoperation • Intraoperative forced duction test • Minimize the amount of sharp dissection • The optimum position of the suture may be at the most posterior extent of the blunt dissection exposing the EOM

  15. 9 pts : standard BMR posterior fixation surgery with scleral sutures: 2 – only scleral faden 7 – BMRc + scleral faden Postoperatively: 6/9 – imroved stereoacuity 8/9 – no longer needed bifocals  D/N disparity average of 12∆ 13 pts : BMR  pulley posterior fixation: 3 – only pulley posterior fixation 10 – BMR +pulley post fixation Postoperatively: 8/13 – improved stereoacuity 12/13 – no longer needed bifocals  D/N disparity average of 14∆ Medial rectus pulley posterior fixation is as effective as scleral posterior fixation for acquired ET with high AC/A R A. Clark, J L. Demer Am J Ophthalmol 2004

  16. 3 recent pulley suture patientsPatient 1 • 5yo • Dcc 30pd; Ncc 50pd • Refr RT +2.5D ; Lt +3.0D • Sx: BMR 5.5 (Parks) + pulley post fix • 1mo postop: Dcc 6pd; Ncc 12pd

  17. Patient 2 • 14yo. • Swimming pool ET L only. +4 DS OU • Dsc 35pd Nsc 40 • Dcc 6pd Ncc 16pd • Sx: Lt MR pulley • 1mo after Dsc 20pd Nsc 20pd

  18. Patient 3 • 5yo • Dcc 25pd; Ncc 45pd • LET; Lt amblyopia 6/36 • Refr: RT +4.5D Lt +5.5D • Sx: BMR 5mm (for 35pd) + pulley post. fix. • 1week postop.: Dcc 12pd; Ncc 14pd

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