## **Core Concept**
Horner's syndrome is a neurologic disorder characterized by a triad of ptosis (drooping eyelid), miosis (pupillary constriction), and anhidrosis (absence of sweating) on one side of the face. It results from disruption of the sympathetic nerves supplying the eye.
## **Why the Correct Answer is Right**
The correct answer, , indicates an increase in intraocular pressure. Horner's syndrome is actually associated with a decrease in intraocular pressure due to the interruption of sympathetic nerves that normally cause vasodilation of the ocular vessels and relaxation of the smooth muscle in the eye. The other options are all features of Horner's syndrome.
## **Why Each Wrong Option is Incorrect**
* **Option A:** Ptosis is a classic feature of Horner's syndrome due to the interruption of sympathetic nerves supplying the superior tarsal muscle, which assists in eyelid elevation.
* **Option B:** Miosis occurs because of the unopposed action of the parasympathetic nerves on the pupil, leading to constriction.
* **Option D:** Anhidrosis (lack of sweating) on the affected side of the face is another hallmark of Horner's syndrome.
## **Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that Horner's syndrome can be a sign of an underlying serious condition such as Pancoast tumor (a type of lung cancer) or a stroke, especially if it presents in adults.