Dilated pupil is seen in all of the follow ing EXCEPT
**Core Concept**
A dilated pupil is characterized by a larger than normal diameter of the pupil, often resulting from paralysis of the parasympathetic nervous system or stimulation of the sympathetic nervous system. This can be caused by various conditions affecting the autonomic nervous system, including neurological disorders, trauma, or the use of certain medications.
**Why the Correct Answer is Right**
The correct answer is likely related to conditions that typically cause a constricted or pinpoint pupil, rather than a dilated one. This is often seen in conditions such as acute angle-closure glaucoma, which is caused by a sudden increase in intraocular pressure that stimulates the oculomotor nerve, leading to a constricted pupil. Other conditions, such as Horner's syndrome, may also result in a dilated pupil on the affected side due to disruption of the sympathetic nervous system.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option may be incorrect if it refers to a condition that typically causes a dilated pupil, such as trauma or the use of certain medications like atropine or cocaine.
* **Option B:** This option may be incorrect if it refers to a condition that typically causes a dilated pupil, such as third nerve palsy.
* **Option C:** This option may be incorrect if it refers to a condition that typically causes a dilated pupil, such as pontine glioma.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that a dilated pupil can have various causes, and a thorough history and physical examination are crucial in determining the underlying condition. In some cases, a dilated pupil may be a sign of a life-threatening condition, such as acute angle-closure glaucoma or third nerve palsy.
**Correct Answer: C. Pontine glioma.**