A Mechanical Device for Blepharospasm

Overview

Idiopathic blepharospasm (IB) is a rare but well characterised adult onset focal dystonia that may cause severe visual disability. The most effective treatment is with periodic injections of botulinum toxin into the pre-tarsal and / or pre-septal orbicularis oculi muscles bilaterally. However, even with treatment, practical visual function often remains compromised. A subset of IB sufferers find that eye opening improves with focal unilateral digital pressure usually on a specific point on the temple. The Investigators have developed a spectacle mounted spring-loaded prosthesis (the "Pressop" device) to apply continuous individually localised focal pressure on the temple to mimic the effect of finger pressure. The Investigators recommended a trial of this simple safe device in those IB patients who report improvement in eye opening with focal digital temple pressure.

Idiopathic blepharospasm is a rare chronic neuro-ophthalmic disorder that causes substantial visual handicap \& compromises quality of life. It affects adults, women more than men, usually beginning in the 5th or 6th decade and consists of repeated forceful bilateral spasms of eye closure with photophobia and ocular surface discomfort. In up to a third of cases there are synchronous mid and / or lower facial spasms and the spectrum of disorder extends to cranial dystonia involving jaw \& neck muscle spasms (e.g. antecollis or retrocollis). Practical visual function is variably affected but most patients will have to stop driving, many cannot work, manage the house or even leave the house unaccompanied. Leisure activities such as reading \& watching television are compromised or impossible, and secondary mood dysphoria and depression are common. In some cases, patients have discovered that applying focal finger pressure, usually to the temple, relieves or even abolishes the spasms for the duration of the application. It is, however, difficult for the patient to sustain the finger pressure and impossible to apply it during activities when eyesight is important e.g. driving, typing or other bimanual tasks. The phenomenon can be regarded as the equivalent of the sensory trick (ST or geste antagonistique) seen in some cases of spasmodic torticollis whereby finger tip pressure on the chin prevents or reduces the muscle spasms in the neck and allows the head to be held straight. In this study, the Investigators explored the hypothesis that the benefit of the finger-tip pressure sensory trick could be replicated by a spring-loaded, spectacle mounted device applying focal pressure to the temple. Following preliminary design trials, the investigators commissioned a manufacturer to develop a light easily handled pressure device that could be fixed to the frame of most spectacles. The "Pressop" device fulfils these criteria and was adopted for the trial.