Mydriasis due to Anticholinergic Toxicity: This condition is characterized by the dilation of pupils due to the blockade of acetylcholine receptors in the eye, leading to loss of parasympathetic tone. It's a common cause of bilateral mydriasis and can be seen in various clinical settings, including drug overdose or exposure to certain medications.

Third Cranial Nerve (Oculomotor Nerve) Palsy: This condition can cause pupillary dilation due to the disruption of parasympathetic fibers that control pupil constriction. It can be caused by various factors, including aneurysms, trauma, or tumors.
Adie's Pupil (Tonic Pupil): A condition characterized by a dilated pupil that reacts poorly to light but has a more pronounced response to near vision. It's often benign but can be associated with systemic diseases.
Traumatic Mydriasis: Direct trauma to the eye can cause damage to the iris sphincter or the nerves controlling pupil size, leading to dilation.

Subarachnoid Hemorrhage: Although less common, a subarachnoid hemorrhage can cause sudden, severe headache and, in some cases, alterations in pupil size due to increased intracranial pressure affecting cranial nerves.
Brainstem Stroke: Strokes affecting the brainstem can lead to pupillary abnormalities, among other neurological deficits, due to the critical structures located in this area.
Pituitary Apoplexy: A medical emergency where a pituitary tumor suddenly hemorrhages or infarcts, potentially causing acute increase in intracranial pressure and affecting nearby structures, including cranial nerves.

Congenital Conditions (e.g., Congenital Mydriasis): Rare conditions present at birth that can affect the size and reactivity of the pupils.
Infectious Diseases (e.g., Neurosyphilis): Certain infections can affect the central nervous system and cause pupillary abnormalities, among other symptoms.
Parasympatholytic Drugs: Certain medications or substances that can cause mydriasis by blocking parasympathetic input to the eye.