Under normal conditions, pupils are round with smooth edges. Deformations in pupils are typically linked to local iris diseases but can also occur due to issues with the innervation of the pupil’s motor system at various levels. It’s important to differentiate between pupil deformations caused by local diseases and those resulting from internal organ diseases that affect the central nervous system.
When changes in pupil shape are noted in one eye, they usually indicate a potential disease. There are eight types of pupil deformations:
Changes in pupil parameters observed in one eye are often indicative of a disease and can also appear in both eyes as signs of hereditary predisposition. Deformed pupils that result from “melting” of certain parts of the pupillary margin, rather than a shift in the pupillary belt stroma, are considered false variants. Multiform deformations are frequently seen in patients with brain tumors.
When using a slit lamp, a flatness of at least one-sixth of the pupil’s circumference (equivalent to 2 hours on a clock face) is considered significant for diagnosis. Computer software can now detect changes with up to four times more precision, identifying variations as small as 0.1 hours.