Causes of<unk>  range from benign (normal) to life-threatening conditions. Clinically, it is important to establish whether<unk>  is more apparent in dim or bright light to clarify if the larger pupil or smaller pupil is the abnormal one. *<unk>  which is worsened (greater asymmetry between the pupils) in the dark suggests the small pupil (which should dilate in dark conditions) is the abnormal pupil and suggests Horner's syndrome or mechanical<unk> . In Horner's syndrome sympathetic nerve fibers have a defect, therefore the pupil of the involved eye will not dilate in darkness. If the smaller pupil dilates in response to instillation of apraclonidine eye drops, this suggests Horner's syndrome is present. *<unk>  which is greater in bright light suggests the larger pupil (which should constrict in bright conditions) is the abnormal pupil. This may suggest Adie tonic pupil, pharmacologic dilation, oculomotor nerve palsy, or damaged iris. A relative afferent pupillary defect (RAPD) also known as a Marcus Gunn pupil does not cause<unk> . Some of the causes of<unk>  are life-threatening, including Horner's syndrome (which may be due to carotid artery dissection) and oculomotor nerve palsy (due to a brain aneurysm, uncal herniation, or head trauma). If the examiner is unsure whether the abnormal pupil is the constricted or dilated one, and if a one-sided drooping of the eyelid is present then the abnormally sized pupil can be presumed to be the one on the side of the ptosis. This is because Horner's syndrome and oculomotor nerve lesions both cause ptosis.<unk>  is usually a benign finding, unaccompanied by other symptoms (physiological<unk> . Old face photographs of patients often help to diagnose and establish the type of<unk> . It should be considered an emergency if a patient develops acute onset<unk> . These cases may be due to brain mass lesions which cause oculomotor nerve palsy.<unk>  in the presence of confusion, decreased mental status, severe headache, or other neurological symptoms can forewarn a neurosurgical emergency. This is because a hemorrhage, tumor or another intracranial mass can enlarge to a size where the third cranial nerve (CN III) is compressed, which results in uninhibited dilatation of the pupil on the same side as the lesion.
Anisocoria
Sclerocornea
Megalocornea
Leukocoria
Periorbital hyperpigmentation
Mechanical anisocoria
Papilledema
Macropsia