Sunday, September 14, 2008

Botulinum toxin injection plus refractive surgery play complementary roles


Botulinum toxin injection can be a useful adjunct to refractive surgery used either before surgery to treat existing oculomotor anomalies or postoperatively to address a secondary deficit of motor fusion, said Silvia Brogelli, MD at the XXVI Congress of the ESCRS.

Dr Brogelli presented findings from a retrospective review that identified 50 adult patients who had been treated between 1988 and 2008 with botulinum toxin injections into hyperactive extraocular muscles and also underwent refractive surgery.

The series represented two subgroups. Group 1 comprised 31 patients who had previously received one or more botulinum toxin injections for ocular misalignment or nystagmus and subsequently underwent refractive surgery. Group 2 included 19 patients with a history of refractive surgery who were subsequently treated with botulinum toxin to improve ocular motility. Cases with blind deviated eyes were excluded.

Considering that the benefit of botulinum toxin is time-limited and permanent stable binocular cooperation is reached in few cases, the time interval between repeated injections was used as a surrogate measure of comfortable binocular single vision and the criterion for measuring treatment efficacy.

There were no complications associated with the combination treatment. In patients who were receiving botulinum toxin as primary treatment for ocular misalignment, the mean interval between subsequent injections increased significantly after refractive surgery. Among the patients who received botulinum toxin to treat a secondary deficit of motor fusion after refractive surgery, all attained stable binocular cooperation either permanently (63 per cent) or with annual botulinum toxin injections (37 per cent).

“The sensorial changes caused by refractive surgery can affect oculomotor balance. Considering the well-recognised beneficial role of correcting hypermetropia in treating refractive accommodative esotropia, this change may be useful. On the other hand a potential for strabismic complications after refractive surgery exists,” said Dr Brogelli, Centro Oculistico, Firenze, Italy.

“Our experience shows that improving vision with refractive surgery in patients with intermittently deviated eyes being treated with botulinum toxin enhances fusion. In addition, botulinum toxin treatment provides patients the opportunity to be considered candidates for refractive surgery if they have been excluded because of poor binocular vision associated with hyperactive extraocular muscles.”

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