A case of paradoxical diplopia in large-angle consecutive exotropia.
OBJECTIVE
To describe the investigation and subsequent management of paradoxical diplopia in unsightly exotropia. A 32-year-old lady requested surgical correction of a large manifest consecutive exotropia which, on initial correction with any base-in prism, was accompanied by paradoxical diplopia.


METHODS
Botulinum toxin to the right lateral rectus reduced the deviation to 30 delta over a one-week period. The residual deviation was corrected with base-in Fresnel prisms which the patient wore constantly for another two weeks. Although there was demonstrable diplopia initially, it disappeared after 3-4 days of prism wear. Surgery was carried out comprising right lateral rectus recession (6 mm) and right medial rectus advancement from 12 mm to 6 mm posterior to the limbus.


RESULTS
There was no diplopia following the surgery and the residual exodeviation measured 6 delta for near and 16 delta for distance (fixing OD). The patient remains symptom-free and cosmetically excellent.


CONCLUSIONS
A gradual progressive reduction in the deviation using a combination of Botulinum toxin and prisms allowed a more informative conclusion to be made regarding the potential post-operative sensory status in this patient, by allowing her to slowly adjust to an altered ocular alignment. In patients with non-functional strabismus who may be at risk from post-operative diplopia, a trial with prisms over a few weeks with or without the addition of Botulinum toxin is advocated.
Deacon
Mark A
MA
Orthoptic Department, Leeds General Infirmary, Belmont Grove, Leeds, U.K. markadeacon@hotmail.com
D000328:Adult; D001905:Botulinum Toxins / Q000627:therapeutic use; D004172:Diplopia / Q000209:etiology* / Q000628:therapy; D005099:Exotropia / Q000601:surgery*; D005139:Eyeglasses; D005260:Female; D006801:Humans; D055095:Optics and Photonics; D011183:Postoperative Complications / Q000209:etiology* / Q000628:therapy; D015348:Vision, Binocular / Q000502:physiology
D001905:Botulinum Toxins