Squint Free Papers - aioseducation

Squint Free Papers
one eye. In recent years botulinum toxin has been most commonly used for
symptomatic relief.
Botulinum toxin works by causing a flaccid paralysis of the injected muscle
and the eye position changes allowing the visual axes to align. It is known that
contracture of medial rectus occurs even in patients who have recovered fully
and having small angle esodeviation. 2 Botulinum toxin acts as therapeutic
agent by preventing the contracture of the medial rectus muscle. Scott and
Kraft in 1985 used botulinum toxin for strabismus concluded that it helped
in achieving single binocular vision in many patients. 3 Contracture release
was explained as relaxation of sarcomere overlap occurring in the ipsilateral
antagonist (medial rectus muscle).
Botulinum toxin can be given directly in the muscle or subtenon’s space with
or without electromyographic (EMG) guidance in the office setting. 4,5
Ophthalmologists have used 2.5 units to as high as 15units in a single muscle
but the effect of toxin in terms of response as measured in prism dioptre of
deviation is not known whether used with or without electromyographic
(EMG) assistance. 6
To evaluate the effect, complications and dose response of botulinum toxin
A injection in the treatment of sixth nerve palsy without electromyographic
(EMG) assistance.
MATERIALS AND METHODS
• Design: Retrospective interventional case series.
• Inclusion criteria: Initial examination within three months of history of
sixth nerve involvement, Inability to abduct one eye, Diplopia in primary
position, Distance esotropia ≥ 10 prism dioptres, No previous botulinum
toxin or surgical treatment
• Exclusion criteria: History of strabismus prior to sixth nerve palsy, Any
other cranial nerve palsies, Pregnancy
• Data including age, sex, date of onset of palsy, etiology of palsy, systemic
condition, degree of abduction deficit and angle of deviation. The amount
of esotropia in primary position at 6m and 33cm was recorded by prism
and alternate cover test pre and post botulinum injection visits.
• Abduction deficit was graded by using the scale 0 (normal), -1 (can rotate
eye from midline to 75% of full rotation), -2 ( to 50% of full rotation), -3 ( to
25% of full rotation),-4 (to midline) and -5 (inability to rotate to midline).
• Injection technique: Botulinum toxin [Botox ® ] (Allergan) was be used in
all patients transconjunctivally under topical anaesthesia (Proparacaine)
967