Asthenocoria, also known as Arroyo’s sign, refers to a condition in which the pupils exhibit slow dilation or constriction in response to changes in light intensity. Patients may experience photophobia if pupillary constriction occurs gradually. The abnormal pupillary response may be unilateral or bilateral.

Pathophysiology

Normal pupillary responses are mediated by the autonomic nervous system: parasympathetic fibers constrict the pupil via the sphincter pupillae, and sympathetic fibers dilate the pupil via the dilator pupillae. In asthenocoria, this reflex is slowed due to dysfunction of these autonomic pathways, commonly secondary to systemic disorders such as adrenal insufficiency or neurological impairment. Impaired adrenal hormone levels can affect sympathetic tone, leading to delayed pupillary reactions.

Examination Technique

• Patient positioning: Seated comfortably in a dimly lit room.

• Observation: Inspect both pupils for symmetry, size, and shape.

• Light response test: Shine a penlight into each eye separately, observing for the speed and extent of pupillary constriction and dilation.

• Accommodation test: Ask the patient to focus on a near object, then a distant object, noting the speed of pupillary constriction and dilation.

• Documentation: Record whether the abnormal response is unilateral or bilateral and whether photophobia is present.

Clinical Utility

• Indicator of systemic disease: Asthenocoria may signal underlying adrenal insufficiency or autonomic dysfunction.

• Supportive diagnostic clue: It is not pathognomonic; additional laboratory and imaging studies are often required.

• Monitoring: Changes in pupil response over time may assist in evaluating disease progression or response to therapy.

Differential Diagnosis

History and Physical Examination

History

 Ask about systemic symptoms (fatigue, hypotension, GI disturbances), medication use, recent infections, or endocrine disorders.

Examination:

Assess for other signs of autonomic dysfunction (orthostatic hypotension, dry skin, abnormal sweating), adrenal insufficiency (hyperpigmentation, salt craving), and neurological deficits.

Diagnostic Approach

• Laboratory tests: Serum cortisol, ACTH, electrolytes, and fasting glucose.

• Autonomic function tests: Heart rate variability, blood pressure response to posture changes.

• Ophthalmologic assessment: Slit-lamp examination, pupillometry, and neurological evaluation.

• Imaging: Brain MRI or CT if central lesions are suspected.

Management

• Underlying disorder treatment:

  • Adrenal insufficiency: Lifelong glucocorticoid and mineralocorticoid replacement.

  • Autonomic neuropathy: Optimize underlying disease control (e.g., diabetes management), and symptomatic therapy for orthostatic hypotension or GI symptoms.

• Symptom relief: For photophobia, use tinted lenses or dim lighting as needed.

• Medication review: Adjust drugs affecting autonomic function if appropriate.

Patient counseling

• Explain the importance of monitoring pupillary changes as part of evaluating systemic or neurologic conditions.

• Educate patients about symptoms of adrenal insufficiency and autonomic dysfunction.

• Advise on regular follow-up for laboratory and ophthalmologic evaluations.

• Reassure that the pupillary abnormality itself is not harmful but signals an underlying condition requiring attention.

Pediatric considerations

• Rare in children; when present, evaluate for congenital adrenal disorders, autonomic dysfunction, or neurologic lesions.

• Monitor for associated systemic symptoms.

Geriatric considerations

• Pupillary responses naturally slow with age; differentiate normal age-related changes from pathological asthenocoria.

• Consider polypharmacy and comorbidities affecting autonomic function.

Key points

• Asthenocoria is a clinical sign indicating slow pupillary reaction to light.

• Often associated with adrenal insufficiency and autonomic dysfunction.

• Not diagnostic alone; requires evaluation of systemic, neurologic, and ophthalmologic status.

• Management focuses on underlying disorder and symptomatic relief.

References

1. Buttaro TM, Tybulski J, Bailey PP, Sandberg-Cook J. Primary Care: A Collaborative Practice. St. Louis, MO: Mosby Elsevier; 2008. p. 444–447.

2. McCance KL, Huether SE, Brashers VL, Rote NS. Pathophysiology: The Biologic Basis for Disease in Adults and Children. 8th ed. Maryland Heights, MO: Mosby Elsevier; 2019.

3. Fraunfelder FW, Roy FH. Current Ocular Therapy. 6th ed. Philadelphia, PA: Elsevier; 2018.

4. Tintinalli JE, Stapczynski JS, Ma OJ, Yealy DM, Meckler GD, Cline DM. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. New York, NY: McGraw-Hill; 2020.