What is a typical concentration of Pilocarpine used in the diagnosis of Adie's tonic pupil?

Pilocarpine is a muscarinic agonist used in the diagnosis of Adie's tonic pupil, which is characterized by a dilated pupil due to insufficient parasympathetic function. In this condition, low concentrations of pilocarpine are typically employed because they will elicit a greater response in the affected eye compared to healthy eyes.

The concentration of 0.125% pilocarpine is particularly effective in differentiating Adie's tonic pupil from other causes of pupil dilation, as it is strong enough to provoke constriction in the denervated pupil while having minimal effect on normal pupils. This is due to the supersensitivity of the muscarinic receptors in the affected eye, allowing for noticeable constriction.

Higher concentrations, such as 0.5% or 1%, may cause significant constriction in normal pupils as well, making it less useful in this diagnostic context. A concentration of 0.025% is too weak and may not produce a noticeable effect. Therefore, the use of 0.125% pilocarpine is considered optimal for confirming the presence of Adie's tonic pupil by demonstrating a markedly stronger response in the affected eye.