The pupil, the dark center of the eye, typically functions as a single opening that adjusts in size to control the amount of light reaching the retina. In rare instances, however, an eye can present with what appears to be multiple pupils. This ophthalmic condition, known as polycoria, can significantly affect how an individual perceives the world.
Understanding Polycoria
The medical term for having multiple pupils in one eye is polycoria (ICD-10 code Q13.2). This extremely rare condition involves the iris, the colored part of the eye, containing more than one pupillary opening. In cases of true polycoria, each distinct opening possesses its own functional sphincter muscle, allowing it to constrict and dilate in response to light. A typical pupil adjusts its size to regulate light entry, protecting the retina and ensuring clear vision.
Causes and Classifications
Polycoria is generally a congenital anomaly, meaning it is present from birth, though its exact cause is often unknown. It is categorized into two primary types: true polycoria and pseudopolycoria (false polycoria).
True polycoria involves multiple, fully functional pupils, each with its own light-responsive sphincter muscle. This form is exceptionally rare, with only a few reported cases globally.
Conversely, pseudopolycoria is more common, yet still uncommon. It involves holes or defects in the iris that resemble additional pupils but lack a functional sphincter muscle, meaning they do not actively constrict or dilate.
Pseudopolycoria can arise from various factors, including congenital iris defects, ocular trauma, inflammation, or degenerative processes. It is also associated with other developmental abnormalities or syndromes such as Axenfeld-Rieger syndrome, Iridocorneal endothelial (ICE) syndrome, Seckel syndrome, posterior polymorphous dystrophy, and juvenile glaucoma.
Visual Impact and Other Concerns
The presence of multiple pupils can lead to a range of visual disturbances because light enters the eye through multiple apertures. Individuals with polycoria may experience blurred vision, reduced visual sharpness, or dim vision. Glare sensitivity (photophobia) and the perception of halos around lights are common symptoms, particularly in bright environments.
The severity of these visual challenges can vary significantly among individuals, depending on factors such as the number, size, and specific location of the pupils. In some cases, polycoria may be accompanied by other ocular issues, including strabismus (misaligned eyes) or nystagmus (involuntary eye movements).
Diagnosis and Treatment Approaches
Diagnosis
Diagnosing polycoria involves a comprehensive eye examination by an ophthalmologist or optometrist. This process includes assessing visual acuity and performing a slit-lamp examination to inspect the iris and pupils under magnification. Pupil light response tests determine if each pupil is functional, and specialized imaging like optical coherence tomography may confirm the diagnosis.
Treatment
Treatment goals are to improve visual function and alleviate bothersome symptoms. Management strategies are highly individualized, as some individuals with minimal visual impact may not require intervention.
For those experiencing significant visual difficulties, options may include prescribing special contact lenses (opaque or cosmetic) to block light from the extra pupils, or tinted glasses to reduce glare. Surgical intervention, specifically pupilloplasty, reshapes the iris to create a single, more functional pupil (ICD-10 code 08Q0XZZ).