The following is a summary of “Describing Anisocoria in Neurocritically Ill Patients,” published in the November 2023 issue of Critical Care by Saju et al.
Anisocoria, or unequal pupil size, is defined as a difference in pupil size of at least 0.3 mm but up to 2.0 mm. Researchers started a retrospective study to identify optimal cut points for anisocoria based on quantitative pupillometry findings.
They conducted an exploratory, descriptive study using international registry data, including initial observations of patients with paired left and right quantitative pupillometry measurements. Pupil size was measured before and after exposure to light to check for anisocoria.
The results showed 5,769 patients (mean [SD] age, 57.5 [17.6] years; female sex, 2,558 patients [51.5%]; White race, 3,669 patients [75.5%]). Anisocoria, defined as a pupil size difference exceeding 0.5 mm, was found in 1624 patients (28.2%) before light stimulus, and 645 of them (39.7%) also exhibited anisocoria after light stimulus (P<.001). Additionally, anisocoria, defined as a pupil size difference exceeding 2.0 mm, was present in 79 patients (1.4%) before the light stimulus, with 42 of them (53.2%) showing anisocoria after a light stimulation (P<.001).
Investigators concluded that wide variation in anisocoria prevalence using different cut points highlights the need for a universal definition.