What is the term for an enlarged pupil indicating either contraction of the dilator muscle or relaxation of the iris sphincters?

The term for an enlarged pupil is "dilated pupil." This condition typically occurs when there is contraction of the dilator muscle of the iris or relaxation of the iris sphincters, leading to an increase in the size of the pupil. Pupil dilation may be a response to low light conditions or can also occur due to certain medical conditions, medications, or emotional states.

Understanding the mechanism behind pupil dilation is crucial in the context of ophthalmic practice. The autonomic nervous system regulates pupil size, with the sympathetic nervous system responsible for dilation and the parasympathetic nervous system controlling constriction. Therefore, a dilated pupil indicates an active sympathetic response or a reduced parasympathetic tone.

The other terms do not accurately describe an enlarged pupil: "constricted pupil" refers to a smaller size due to contraction of the iris sphincters, "normal pupil" describes pupils that are of standard size and shape under typical conditions, and "fixed pupil" indicates that the pupil does not react to light or changes in accommodation, which can signify serious medical conditions.