History
This 66-year-old woman sustained closed head injury in a car accident 14 months earlier. She also sustained multiple lower limb fractures and uses a walker. Since the accident, her eyes have crossed and she is bothered by constant diplopia.

Examination
Visual acuity with correction is OS 20/25-2 and OS 20/20-1. Glasses are OD +2.00+0.50 X 180 degrees and OS +2.00+0.50 X 10 degrees with a +2.50 add. Adduction is normal in both eyes. Abduction is slightly limited (-1) in the left eye. The right eye does not abduct even to the midline. Approximately 60 prism diopters of right esotropia is present in the primary position while fixing with the left eye. The esotropia increases when fixing with the right eye and in right gaze. The esodeviation is less in left gaze. Saccadic velocity is moderately brisk to the left in the left eye. A floating saccade is present in attempted abduction in the right eye as the eye moves from the adducted position to just short of the midline.

Diagnosis
Bilateral traumatic sixth nerve palsy more severe in the right eye.

Treatment/Surgery
Full tendon transfer shifting the right superior rectus and right inferior rectus to the right lateral rectus was performed. At surgery this patient was noted to have a flaccid right lateral rectus muscle. Because of this, in addition to the full tendon transfer, a 10 mm plication-tuck was done on the right lateral rectus, sparing the anterior artery. Five units of Botox were then injected into the right medial rectus muscle because passive adduction of the right eye was moderately restricted.

Comment
Posteratively the patient had anterior segment ischemia of the right eye characterized by flare and cell, keratic precipitates, and a dilated fixed pupil. This resolved for the most part after intense topical steroid therapy consisting of 1 drop of 1% prednisolone in the right cul-de-sac every 2 hours while awake. This was reduced gradually over the next 4 weeks to 2 drops a day as the anterior chamber flare and cell reaction subsided. Atrophy of the iris stroma persists from the 9 to 12 o’clock meridians. The pupil is also eccentrically dilated to approximately 6 mm with a reduced reaction to light. In addition, during this period, the patient developed cystoid macular edema with visual acuity reduced to 20/200 in the right eye. The retinal lesion was not treated. After 6 weeks, vision improved to 20/30, but the residual pigmentary changes in the macula and a slight increase in the cataract indicate that visual acuity may not improve beyond this level. Primary position alignment is 10 prism diopters of exotropia, and the patient has single binocular vision with a slight left face turn.

This case may demonstrate the vulnerability of an eye in an older patient to anterior segment ischemia after detachment of the vertical recti. It is not clear what role the Botox injection in the medial rectus or for that matter the lateral rectus plication played in the anterior segment ischemia. However, I have seen two other cases of anterior segment ischemia occurring after Botox injection in similar cases where we thought sufficient anterior ciliary circulation remained.