Guanethidine is used in the treatment of which of the following condition?
Thyrotoxic ophthalmopathy
Ptosis
Bell's palsy
Horner's syndrome
Guanethidine (10%) eye drops is useful in decreasing lid retraction in Thyrotoxic ophthalmopathy. It is an adrenergic neuron blocker which acts by inhibiting the release of noradrenaline in response to nerve stimulation.