Pupil Anomalies: Aetiology Overview

Pupil Anomalies: Aetiology

• Benign vs. Serious: Many pupil anomalies are benign, but some indicate serious, even life-threatening, underlying conditions.
• Scope: This guideline focuses on physiological and pathological pupil abnormalities, excluding traumatic, surgical, or pharmacological causes.

Physiological Anisocoria

• Definition: Unequal pupil sizes without a pathological cause.
• Characteristics: Idiopathic, stable, long-standing, and varies with illumination (up to 20% of individuals). Prevalence increases with age.
• Prevalence: Up to 20% of individuals, increasing with age.

Tonic (Adie's) Pupil

• Cause: Parasympathetic denervation at the ciliary ganglion.
• Demographics: Most common in women aged 20-40, a prevalence of 2 per 1,000.
• Potential Associations: Often idiopathic, but can be linked with viral infections (e.g., varicella-zoster), connective tissue diseases (e.g., Sjögren's, rheumatoid arthritis), and general peripheral or autonomic neuropathies.
• Holmes-Adie Syndrome: Associated with absent or poor tendon reflexes.

Horner's Syndrome

• Cause: Interruption of oculosympathetic innervation from the hypothalamus to the orbit (congenital or acquired).
• Age Range: Occurs at any age; birth prevalence ≈ 1 in 6250 (congenital).
• Potential Associations (Serious): Often benign or post-surgical; can indicate carotid dissection, stroke, multiple sclerosis, or neoplasia (e.g., Pancoast tumor).
• Painful Horner's: A common ocular sign of internal carotid artery dissection.
• Pain Presentation: Ipsilateral orbital, facial, or neck pain is reported in up to 58% of cases with internal carotid artery dissection.
• Common Cause in Children: Birth trauma is the most frequent cause in children.

Argyll Robertson Pupil

• Cause: Lesion in the midbrain affecting the pupillary light reflex pathway but sparing the near reaction pathway.
• Association: Commonly associated with neurosyphilis.
• Presentation: Observed during tertiary or late stages of syphilis infection.

Predisposing Factors

• Tonic Pupil: Female gender.
• Horner's Syndrome: Birth trauma (in children).
• Argyll Robertson Pupil: Syphilis

Symptoms of Pupil Abnormalities

• Generally Asymptomatic: Many abnormalities cause no symptoms.
• Possible Symptoms: Pain, photophobia, or visual disturbance may accompany some pupil abnormalities.

Signs of Pupil Abnormalities

• Physiological Anisocoria: Unequal pupil sizes (≥0.5mm) are usually a finding that is simple.

Explore the aetiology of various pupil anomalies, including benign and serious conditions. This quiz covers physiological anomalies such as anisocoria and the Tonic (Adie's) pupil, highlighting their definitions, prevalence, and associations. Test your understanding of these important eye-related topics.