[The application of botulinum toxin A in the treatment of restrictive strabismus in thyroid associated ophthalmopathy].

OBJECTIVE

To observe the clinical effects of botulinum toxin A in the treatment of restrictive strabismus in thyroid associated ophthalmopathy (TAO).

METHODS

Clinical data in 33 patients with restrictive strabismus in TAO treated with botulinum toxin A were analyzed retrospectively. Botulinum toxin A was injected into extraocular muscles guided by electromyography. Clinical data included the eye position, the eye movement and diplopia.

RESULTS

There were 25 cases of vertical strabismus, 3 horizontal strabismus and 5 vertical combining horizontal strabismus in this group. The average degree of horizontal deviation was 35. 00+/-20. 53 (20 - 80 , M = 27. 59 ) , the average degree of vertical deviation was 29. 33+/-17. 27 ( 10 - 100 , M = 27. 5 ) . The average follow-up time was ( 17. 04+/-12. 77) months (5. 00+/-67. 73 months). Sixty one extraocular muscles were injected, including 31 inferior rectus, 16 medial rectus, 10 superior rectus and 4 lateral rectus. Each rectus was injected 6. 48+/-2. 12 times (4 -11times, M = 6). The interval between injections averaged (2.96+/-0. 70) months (0. 50 - 26. 00 months). The deviation degrees was decreased after injections, 15 cases were cured and did not require further surgery, 12 cases were improved and 6 cases showed poor response. The dosage for each injection averaged (8. 16+/-1. 43) U.

CONCLUSIONS

Botulinum toxin A injection has a good effect in the treatment of restrictive strabismus in TAO. Better results were obtained when treated earlier. Compare with paralytic strabismus and comitant strabismus, the dosage of botulinum toxin A in each injection in TAO is higher, the mean changes of degree of deviation is slighter, the interval between injections and the duration of effect is shorter. Injection dosage should increase after repeated injections. Intolerable diplopia could be eliminated in some patients, therefore, a muscle surgery could be avoided.