Adjustable Sutures in Strabismus Surgery

Why use adjustable sutures? Allows binocular alignment to be refined after strabismus surgery Useful in patients in whom standard surgical dosages may not apply i.e. complicated strabismus surgery such as re-operations, orbital fracture, Graves orbitopathy

Adjustable suture technique Advantages – Reduce rate of re-operations Disadvantages – Muscle slippage (7-41% when adjustable suture surgery performed on IR) Function of: – Magnitude of recession performed – Nature of strabismus ( ↑ with fibrotic muscles) – Specific muscle (IR and MR) – Generally tied within 24 hours of initial procedure

Semi-adjustable suture procedure Co-developed by Spielmann & Campo 1 st described in 1993 Aim: decrease the incidence of postoperative muscle slippage yet retain advantages of adjustable suture surgery Involves suturing the corners of the muscle firmly to the sclera at the desired recession point but also placing an adjustable suture through the centre of the muscle

Kushner This study evaluates the procedure wrt muscle slippage In 2000 it became his standard technique for:  Recessing the IR in those patients who he wished to do an adjustable suture  If recessing MR > 12 mm from limbus

Method I 2 groups: 1. Primary treatment group= never undergone surgery OR had but had not previously slipped muscle – 57 patients on 61 muscles – 55 IR and 6 MR 2. Secondary treatment group= semiadjustable suture suture on muscles but had slipped muscle – 7 patients Primary outcome: occurrence of muscle slippage within 6-months after surgery

Method II After the muscle was disinserted, the 2 corner sutures were sewn through the sclera at desired recession distance ~ 5mm apart with needle tracks directed toward each other – Bunches muscle at new insertion – Permits centre of muscle to sag 1-2mm Double-armed suture securing centre of muscle was brought out through insertion and secured with 6.0 polyglactin cinch & tightened to level of 2 corners Reference knot ~ mm anterior to cinch

Method III Postoperative alignment performed on the morning after surgery After adjustment, the distance between the cinch and the knot is measured again, the difference representing the amount of muscle adjustment

Criteria for muscle slippage “Suspect” if: 1. Angle of misalignment changed by > 4 Δ in the direction away from the field of action of the muscle between the measurement taken immediately after post operative suture adjustment to 6 month outcome 2. Versions demonstrated > 1 unit of change in the direction of ↑ underaction (5 point scale 0 to -4) from the 1-week r/v to 6 month outcome Surgically explored (n=4) If not surgically explored, counted as slipped muscle

Results Primary treatment group  n=0 had muscle slippage Secondary treatment group  n=1 had muscle slippage  51 year old male  Left orbital floor # with IR entrapment  3 prior adjustable suture procedures on IR  Found 13.5 mm from insertion  Advanced using non-adjustable technique

Limitations of Semiadjustable suture Limited efficacy for ↑ recession, target an initial overcorrection

Short Tag Noose Technique for Optional & Late Suture Adjustment Aim: to evaluate a new technique which allows the second-stage suture adjustment to be skipped or delayed if the immediate postoperative alignment is satisfactory Evaluate for: 1. Alignment 2. Reoperation 3. Complications

Method Retrospective study Simple and complex strabismus surgery All patients treated by a single surgeon from were evaluated

Method II Fornix incision Recession: standard hang-back Resection: extra 1-3mm of muscle resected and allowed to hang back by same amount to allow for an ↑ or ↓ at adjustment Standard adjustable-suture sliding noose Noose sutures were trimmed to 3mm (short tag noose) and buried under conjunctiva

Method III Patient assessed in recovery room 1-2 hours ± adjusted after procedure and > 24 hours Alignment success: 1. ≤ 10 horizontal 2. ≤ 6 Δ vertical

Alignment Results at 2 months 120 procedures – Children n=27 (22.5%) – Adults n=97 (80.8%) Post operative adjustment n=65  Same day n=56 (46.7%)  Performed or repeated after ≥ 2 days n=18 (15.0%) HorizontalVertical Alignment Success81.0%70.7% Re-operation rate10.0%19.0%

Reoperation Results No statistical difference in:  Success or re-operation rate for simple or complex strabismus  Success rates in time patients adjusted  Success or re-operation rate with children & adults

Complications Slipped muscle n=1 Granuloma n=2 Recurrence of diplopa n=1