Describe blepharospasm and lid retraction.

Blepharospasm and Involuntary Lid Closure

• Benign essential blepharospasm is a focal dystonia causing involuntary, bilateral, forceful contraction of orbicularis oculi.
• It is a disorder of the basal ganglia, not of the eye or the lid.
• Features — onset in the fifth to seventh decade, commoner in women; bilateral and synchronous; beginning as increased blinking and progressing to sustained closure that may render the patient functionally blind despite normal eyes

Lid Retraction

• Lid retraction is present when the upper lid margin lies AT or above the superior limbus, exposing sclera above the cornea, or when the lower lid lies below the inferior limbus
• Thyroid eye disease is much the commonest cause, and lid retraction is its most frequent single sign — occurring through sympathetic overstimulation of MULLER’S muscle, fibrosis and contracture of the levator, and secondary over-action of the levator where a tethered inferior rectus demands increased innervation to elevate the eye
• The named signs of thyroid lid retraction — dalrymple sign (retraction in primary gaze); von GRAEFE sign (lid lag on downgaze, the lid failing to follow the globe); stellwag sign (infrequent blinking); KOCHER sign (a staring frightened appearance); and moebius sign (convergence weakness)
• Other causes — dorsal midbrain (parinaud) syndrome, in which bilateral retraction is collier’S sign, with light-near dissociation and convergence-retraction nystagmus, classically from a pineal tumour; contralateral ptosis, in which the increased innervation driving the ptotic lid raises the normal one by HERING’S law — so correcting the ptosis abolishes the "retraction", and lifting the ptotic lid manually demonstrates it; aberrant third nerve regeneration; over-correction of ptosis surgery; scarring of the anterior lamella; proptosis of any cause; and neonatal transient retraction
• The consequences — a staring appearance with cosmetic and social distress; exposure keratopathy of the superior and inferior cornea; and ocular discomfort
• Management — treat the cause and wait for stability; in thyroid disease no surgery should be undertaken until the disease has been inactive and stable for at least 6 months, and the correct order of surgery is decompression, then squint, then lids.
• Measures — lubricants and taping; botulinum toxin to MULLER’S muscle as a temporary measure; and lid lengthening surgery — levator recession with Muller muscle excision for the upper lid, and a spacer graft for the lower
• Exclude reflex blepharospasm before injecting toxin; dry eye and lid margin disease cause it and are treatable at the surface