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 Emergency Department Evaluation of Anisocoria

Determine if the anisocoria is more pronounced in the light or in the dark by measuring the pupil diameters... The elimination of recent onset Horner syndrome and 3rd nerve paresis in the ED is essential to ensure that conditions requiring emergent treatment are not missed. If no emergency is present an evaluation in neuro-ophthalmology is appropriate.

 Evaluation of anisocoria

The most important question in the evaluation of anisocoria is whether both pupils are normally reactive to light or is one (or both) poorly reactive. If both pupils are reactive, the smaller pupil is abnormal and the lesion is likely in the sympathetic pathway because pupillary constriction (parasympathetic pathway) is intact. If one pupil is poorly or non-reactive (and there is no relative afferent pupillary defect), the larger pupil is abnormal and the lesion is likely in the parasympathetic pathway.

 The assessment of pupils and pupillary reactions

Examination of the pupils and pupillary reflexes are crucial in obtaining an accurate diagnosis of an ophthalmological problem and many other systemic conditions. It is a relatively simple examination that can be performed at most patients’ bedsides and is a skill all doctors should have.

 The Truth Behind David Bowie’s Eyes

I couldn’t believe my eyes when I was scrolling through my Facebook feed on Monday. First, I was shocked to hear of the passing of David Bowie, but I also noticed that along with this news, there were several stories about his iconic eye appearance. I had always been told, and always believed, that David Bowie’s unusual eye appearance was due to heterochromia iridis… I guess I was wrong! After reading a few of these articles, I found that the real reason David Bowie’s eyes appeared to be different colors was because he had anisocoria! Did you know that? Or had you also been duped into believing he had heterochromia?!

 Tox Pupils

Why do we love the pupils in the poisoned patient? The pupil is the window to your poisoned soul. What happens to the pupils after poisoning is a wildly complicated topic masquerading as a simple outcome; they either dilate (mydriasis) or they constrict (miosis). In order to understand how toxins affect the pupils, you have to understand how the pupils work in the first place.

Articles of Interest

Abnormalities of the Pupil

Although pupil anomalies are commonly benign, they may be the first or only manifestation of a serious or even life-threatening disorder.

Adie’s Tonic Pupil

A tonic pupil results from parasympathetic denervation at the level of the ciliary ganglion. It is characterized by a large, regular pupil with decreased response to light but preserved or enhanced constriction to accommodation, segmental iris constriction, vermiform movements of the pupillary border, and hypersensitivity to pharmacologic constricting agents.

An Asymmetrical Pupil

The diagnosis of physiologic anisocoria is clinical, based on history and physical examination findings. Reviewing old photos or driver's licenses of the patient can assist in establishing the diagnosis because physiologic anisocoria is a persistent and long-standing condition. The anisocoria is usually equal in light and darkness

Anisocoria in the ED: Pathophysiology, Evaluation, and Management

The possible etiologies for anisocoria are broad and can range from benign conditions to potentially life-threatening pathologies. It is estimated that physiologic anisocoria, also called simple or essential anisocoria, is present in 10-30% of the population.

Conditions that Affect the Pupil

Up to 20% of healthy people have pupils that are different sizes – some are normal but others are signs of a serious health issue.

Eye: Unequal Pupils

When evaluating the patient with anisocoria, the emergency physician must answer two critical questions: Which pupil is abnormal, the smaller or the larger? and Is this abnormality acute or chronic?

How to examine the pupil

Normal <1mm difference in pupil size.

Pupil Disorders

Pupil size results from the activity of sympathetic and parasympathetic stimulation to the muscles of the iris. Under normal circumstances, bright light causes pupil constriction (miosis) due to increased parasympathetic activity, which stimulates the pupillary sphincter muscles. Dimly lit conditions cause pupil dilation (mydriasis), which results from sympathetic stimulation of the pupillary dilator muscles. Pupil constriction also results from the accommodation reflex, the process responsible for focusing vision on a near object. It is important to note that pupil examination should always be performed under bright ligh

Pupillary responses can signal potentially serious problems

This is a quick way to gauge the integrity of the afferent and efferent systems and can help direct the differential diagnoses and management.

“The eyes are the windows of the soul”...

Altered autonomic responses can be observed in patients in the intensive care unit (ICU), and these changes in abnormal autonomic responses are known to be associated with patient prognosis.

Resources

North American Neuro-Ophthalmology Society

Anisocoria cannot make you go blind. Though many causes of anisocoria are benign and some people only notice some blurry vision and/or light sensitivity, it can be a sign of a serious and potentially life-threatening neurological problem.

StatPearls

Anisocoria is a condition characterized by unequal pupil size. The etiology of anisocoria is complex, ranging from benign to potentially life-threatening causes. Potential etiologies of anisocoria include systemic drug use, topical ophthalmic drug use, headaches, trauma, ophthalmologic diseases, and autonomic ganglion pathology.