Final answer:
Unilateral pupil dilation can stem from ocular drugs like phenylephrine or neurological issues such as Horner's syndrome and oculomotor nerve damage. Phenylephrine causes mydriasis by acting on specific eye muscle receptors, while Horner's syndrome can result from thoracic tumors affecting sympathetic nerves.
Step-by-step explanation:
Unilaterally dilated pupils without an altered mental state can be caused by several factors, including local ocular conditions, pharmacological agents, or neurological concerns. For example, mydriasis, which is the dilation of the pupil, can occur when substances such as phenylephrine mimic the action of norepinephrine on the radial fibers of the iris' smooth muscle. Compounds like phenylephrine are often used as eye drops in a medical setting. As a result, the pupil dilates despite no changes in mental state.Another condition that can cause changes in pupil size is Horner's syndrome, characterized by pupil constriction, ptosis (drooping eyelid), and decreased facial sweating. A tumor in the thoracic cavity can impact the sympathetic pathway, leading to these symptoms. On the other hand, an optic nerve or oculomotor nerve damage can manifest as an abnormal pupillary light reflex.
Testing this reflex with light shined in the patient's eye helps determine if there's nerve damage resulting in abnormal pupil response.Unilaterally dilated pupils without altered mental state can be caused by Horner's syndrome, which is a condition that affects the autonomic functions of one eye, such as pupillary constriction. Horner's syndrome can be caused by a tumor in the thoracic cavity, which can affect the autonomic nervous system. Another possible cause is damage to the optic nerve on one side, resulting in a lack of response to light in that eye.