Botox can help reverse crossed eyes says Chinese University academic

Botox is associated with those seeking beauty, but an academic says it has important medical benefits too. Besides smoothing out wrinkles, Botox can treat strabismus, or crossed eyes.

Flora Lau Hoi-shan, clinical assistant professor in ophthalmology and visual sciences at Chinese University, says Botox has been used to treat patients with crossed eyes in Hong Kong since 2009, and 71 injections have been given to 44 patients at the Hong Kong Eye Hospital.

Botox works by blocking nerve endings and paralysing muscles. While the effects are temporary in most patients and repeat injections are usually needed to keep the eye straight, the success rates are about 80 per cent for near vision and 60 per cent for distant vision.

Lau encourages Botox use for treating patients with convergent strabismus caused by treatment for nasopharyngeal cancer, one of the city's top seven cancers.

Radiotherapy is one of the main treatments for the cancer, but one of its key complications is sixth-nerve palsy, which can lead to crossed eyes when the muscles that move the eyeball outwards lose the strength to do so. The deficiency leads to double vision and poor depth judgment.

To correct this, Botox is injected into the medial rectus, the muscle used for inward eye movement. As this weakens, the two muscles become balanced and the eyeball returns to the middle position.