From the Research
Adie's tonic pupil is a neurological condition characterized by a pupil that responds slowly to light but constricts more completely and for longer periods when focusing on near objects, due to damage to the ciliary ganglion or postganglionic parasympathetic fibers that innervate the pupillary sphincter and ciliary muscles, as reported in the most recent study 1. The physiology of Adie's tonic pupil involves denervation hypersensitivity, where the pupillary sphincter becomes supersensitive to cholinergic substances.
- The affected pupil is larger than normal in ambient lighting and constricts slowly or minimally to direct light stimulation.
- It shows enhanced constriction with near vision (accommodation) due to aberrant reinnervation of the ciliary muscle fibers to the pupillary sphincter.
- This explains the characteristic "tonic" response where the pupil constricts slowly during near vision and dilates even more slowly when looking at distant objects. Diagnosis can be confirmed using dilute pilocarpine (0.125%), which causes marked constriction in the affected pupil due to denervation hypersensitivity but has minimal effect on normal pupils, as demonstrated in a case report 2. Adie's tonic pupil is often benign and part of Adie's syndrome when accompanied by diminished deep tendon reflexes, but patients should be monitored for other neurological symptoms that might indicate a more serious underlying condition, such as Sjögren's syndrome, which has been associated with bilateral tonic pupils 3. The condition has been studied extensively, with earlier reports providing valuable insights into its characteristics and associated conditions, including a study from 1977 that highlighted the importance of serologic tests for syphilis in patients with Adie's syndrome 4. However, the most recent and highest-quality study 1 provides the most relevant and up-to-date information on the physiology of Adie's tonic pupil.