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) Surgical goals: 1 Alleviate symptoms 2 Reduce N deviation without altering D 3 Improve binocularity 4 Eliminate need for bifocals Group A Group B D- ortho or microtropia N- ET Good chance for binocularity and high grades of stereo D- ET Chance for binocularity low or absent

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)

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 Result Augmented BMR BMR+ faden Alignment 100% Bifocals 84% Spectacles 9/25 80% 57% 5/21

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

Augmented BMR by Wright for ET with high hypermetropia Standard Augmented 74% alignment + full correction 26% undercorrections 88% Alignment 12% XT + full correction Overcorrections were treated by reduction of “+” 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

Kushner: should you overcorrect and cut the plus? 22 pts with consec XT 8/22 14/22 Low + High + Low - < + 2.5D High - > + 2.5D High AC/A 88% 36% Low+ High+ Results Low + High+ Alignment Gross stereo(800) Good stereo<200 Reoperations 88% 75% 63% 13% 30% 14% 7% 29%

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

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%

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

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

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

main mechanism - mechanical restriction of movement through the pulley 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

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

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 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∆

3 recent pulley suture patients Patient 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

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

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