The Harada–Ito procedure is an
eye muscle operation designed to improve the
excyclotorsion experienced by some patients with
cranial nerve IV palsy. In this procedure, the
superior oblique tendon is split, and the anterior fibers – the fibers most responsible for
incyclotorsion – are moved anteriorly and laterally. This selectively stretches and tightens these fibers, enhancing the incyclotorsion power of the superior oblique.
The most common indication for the Harada–Ito procedure is bilateral acquired cranial nerve IV palsy following closed
head trauma
A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
(particularly automobile accidents). In this clinical situation the vertical imbalance is often less symptomatically bothersome to the patient than the induced excyclotorsion. Affected patients have a particularly annoying type of double vision (
diplopia
Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...
), wherein the images are twisted (excyclotorted).
Patients with cranial nerve IV palsy whose complaints are not specifically limited to torsional diplopia, but instead also have significant vertical diplopia, are not good candidates for a Harada–Ito procedure. Instead, a recession of the
inferior oblique
The inferior oblique muscle or obliquus oculi inferior is a thin, narrow muscle placed near the anterior margin of the floor of the orbit. The inferior oblique is one of the extraocular muscles, and is attached to the maxillary bone (origin) and ...
muscle, or another
strabismus
Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. The eye that is focused on an object can alternate. The condition may be present occasionally or constantly. If present during a ...
operation may be indicated.
See also
*
Eye surgery
Eye surgery, also known as ophthalmic or ocular surgery, is surgery performed on the eye or its adnexa, by an ophthalmologist or sometimes, an optometrist. Eye surgery is synonymous with ophthalmology. The eye is a very fragile organ, and requ ...
References
* Metz H, Lerner H: The adjustable Harada–Ito procedure. Arch Ophthalmol 1981;9
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{{DEFAULTSORT:Harada-Ito procedure
Eye surgery