What is a characteristic of a tonic pupil?

A tonic pupil is characterized by its dilated appearance and sluggish or slow response to light stimuli. This condition, which can result from damage to the postganglionic fibers of the ocular sympathetic pathway, leads to a notable discrepancy in how the pupil reacts compared to a normal pupil. In addition, when light is shone into a tonic pupil, it responds poorly, often appearing to remain dilated and reactive over a prolonged period rather than constricting quickly.

The nature of this pupil being dilated and showing a delayed reaction is pivotal in differentiating tonic pupils from other types, such as a normal or constricted pupil, which would react more swiftly and effectively to light. Understanding these characteristics is crucial for diagnosing underlying neurological conditions that could lead to such pupil changes.