Paradoxical pupillary reflex, also known as the reverse pupillary reflex or hippus, is a phenomenon where the pupils of the eyes appear to dilate in response to external light stimulation, contrary to the normal constriction response. This reflex is often seen in cases where the optic pathway or parasympathetic innervation to the iris is damaged or disturbed.
The normal pupillary reflex, known as the pupillary light reflex, involves constriction of the pupils when exposed to bright light to protect the retina from excessive light exposure. This reflex is regulated by the autonomic nervous system, specifically the parasympathetic nervous system, which causes contraction of the iris sphincter muscle.
In paradoxical pupillary reflex, however, the damaged or disrupted neural pathways interfere with the normal functioning of the autonomic nervous system, leading to abnormal pupil behavior. Instead of constricting when exposed to light, the pupils dilate or fluctuate in size, appearing to rhythmically expand and contract.
This paradoxical response may be indicative of various underlying disorders or conditions, such as damage to the optic nerve, oculomotor nerve dysfunction, or central nervous system abnormalities. It can also occur as a result of certain medications or drug effects.
The paradoxical pupillary reflex is typically diagnosed through a clinical examination of the eyes and neurological tests. Management of this condition involves addressing the underlying cause if possible, and treating any associated symptoms or complications.
In summary, paradoxical pupillary reflex refers to the abnormal dilation or fluctuation of pupils in response to light due to damage or disruption of the optic or parasympathetic pathways in the nervous system.
