Patient with anisocoria...
A. Diagnostic approach: key questions to ask in the evaluation of the patient with anisocoria
1. The first question to ask: Which eye is abnormal?
2. The second question to ask: Could the abnormal pupil be due to primary ocular disease?
3. If intraocular disease is not present, a neurologic cause of anisocoria is sought.
4. If the mydriatic (dilated) pupil is abnormal - is it an afferent (retina, optic nerve) or efferent (parasympathetic) lesion?
5. If the miotic (constricted) pupil is abnormal - is it a pre-ganglionic or post-ganglionic sympathetic lesion?
B. How do you determine which eye is abnormal?
1. In most patients with anisocoria, only one eye is abnormal.
Less often, both eyes are abnormal. May see with brain trauma (see later) or multiple separate primary ocular disease conditions.
2. How to look for pupil asymmetry
a. Examine from an arm's length away from patient so you can see both eyes simultaneously.
b. Dark room - use retroillumination to view tapetal reflex through pupils.
3. Which is abnormal - the miotic or mydriatic pupil?
a. Examine in light: if the mydriatic pupil fails to constrict, it is abnormal.
b. Examine in the dark: if the miotic pupil fails to dilate, it is abnormal.