Harada-Ito procedure – Fell’s modification

Originally described in 1964 by Harada and Ito, the procedure is based on the premise that the anterior portion of the superior oblique tendon is primarily concerned with incyclotorsion. Therefore, transposing this part of the tendon anteriorly will manipulate the rotational vectors on the eye in cases of cranial nerve 4 palsy. In the original description, the tendon fibres were not disinserted.

Since the initial description, the procedure has had variation in is execution. Fell modified the original technique in 1974, whereby the anterior portion of the tendon was disinserted, before reinserting it anteriorly and lateral to the insertion of the lateral rectus muscle. Other variations include the use of adjustable sutures to modify the procedure post-operatively to improve accuracy.

Significant excyclotorsion of the eye with symptomatic torsional binocular diplopia in cases of acquired cranial nerve 4 palsy.

Patients who have measured excyclotorsion but are not symptomatic should not have surgery. Patients who have significant vertical diplopia or have a history of definitive abnormal eye muscle anatomy (for example a tight superior oblique) are not good candidates for the Harada-Ito procedure either.

Ophthalmic speculum; St Martins forceps – to complete forced duction testing; fixation of the globe – fixation forceps (straight or curved) or traction suture; Wescott scissors; conjunctival forceps; Fison retractor; simple squint hook; Jameson squint hook; small artery forceps; non-locking curved needle holders; 6-0 double armed absorbable suture; ophthalmic measuring calipers; 8-0 single armed absorbable suture

Communicate with the anaesthetist during muscle manipulation to avoid unwanted complications due to the oculocardiac reflex, death has been reported to occur. Preference on globe fixation is not particularly relevant; the use of fixation forceps or a traction suture are both effective. Removal of the eyelid speculum once the Fison retractor is within the tenons capsule can allow better visibility if required. It is important to ensure the anterior fibres are free of tenons and superior rectus adhesions to maximise the desired surgical outcome.

Repeatable orthoptic measurements using a synoptophore demonstrating a pronounced excyclotorsion with minimal vertical deviation is the key indication for this procedure. Be sure a masquerading diagnosis such as myasthenia gravis is not the cause. The patient must be aware of the risks of general anaesthetic and risks of surgery, including the required post-operative recovery period in relation to driving, work and/or leisure (for example no swimming for a minimum of 2 weeks). They must be aware of the alternatives to this procedure, including simple patching of the eye to abolish double vision or doing nothing.

The superior oblique tendon can have a varied insertion on the globe, which can affect surgery. The width and location of the insertion can be variable, and the presence of tendon bifurcation or dual head insertion has been described. There are principles that can standardise the surgical approach. For example, the superior oblique tendon is always beneath the superior rectus, and isolating this muscle first is crucial. Furthermore, by instrumental strumming or painting the tendon (with the patients’ blood) you can improve visualisation of this thin, translucent tissue. The use of an operating microscope is advisable to aid in this regard further.

Vortex veins can complicate any eye muscle surgery with significant bleeding. Usually, the superotemporal vortex vein is located temporal to the superior oblique tendon, away from the surgical field. But occasionally the vein can be located at the point of tendon insertion or even split tendon fibres. Therefore, prior to manipulating the superior oblique tendon, adequate visualisation is key to avoid potential damage of the vein and subsequent bleeding.

Intraoperative complications: Conjunctival bleeding is usually easily controlled with light cautery; vortex vein bleeding is rare but difficult to control and may require prolonged pressure to the bleed site, elevating the head and/or abandonment of the surgery including close follow up for other complications such as choroidal haemorrhage and very rarely orbital compartment syndrome post-operatively; accurate suturing of tendon fibres reduces the risk of tendon/muscle slippage; if there is a suspicion of scleral perforation whilst suturing then examination of the retina to visualise any retinal break/haemorrhage is compulsory.

Post-operative complications: A sore, gritty, watery and/or red eye is unavoidable and transient; tenons cyst formation and/or conjunctival inflammation often settles with topical steroids and observation, but cysts occasionally need further surgery; undercorrection or overcorrection are often accompanied with continued or worse symptoms and can be quantified by orthoptic assessment, the need for further surgery may be discussed; visual loss due to infection or retinal detachment is very rare and requires case by case management.

Operating on the incorrect eye or incorrect muscle may be noted intra- or post-operatively, this is rare but if it occurs or is suspected to have occurred then full disclosure to the patient and options available must be discussed.

None.

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Fells P. Surgical management of excyclotorison. Int Ophthalmol Clin. 1976; 16:161–170.
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