Pupillometry as a method for monitoring of pupillary light reflex in ICU patients

Quantitative assessments of pupillary light reflexes in neurocritically ill patients

“…In addition, the percentage change (%CH) in pupil constriction was analyzed using the difference between the maximum and minimum pupil diameters. The NPi is calculated by a proprietary algorithm using multiple parameters, including latency, CVs, pupil diameter at baseline, percentage of change, and DVs (Table 1) [2][3][4][5][6][7][8][9][10][11][12][13][14][15]17,18]. In %CH, %CH ≥ 15% is considered a normal and brisk response, %CH < 15% is a sluggish response, and 0%CH indicates a fixed pupil response.…”

“…In addition, a PPI score < 4 is usually considered adequate for pain control [22][23][24][25]. Quantitative pupillometers provide more reliable, accurate, and objective measurements and have higher inter-rater reliability than manual pupil examinations [9,[13][14][15]17,18].…”

“…In addition, changes in PLR could strongly predict neurological worsening after acute brain injury [2,3,6,7]. Under normal conditions of pupillary reactive responses, the stimulant signal of retinal cells is carried through the synapse between the optic nerve and the optic tract in the pretectum of the midbrain, which projects to the Edinger-Westphal nucleus in the dorsal midbrain [2,4,8,9]. After stimulation of the Edinger-Westphal nucleus, the parasympathetic signal is delivered by the oculomotor nerve to the superior orbital fissure of the eye and ciliary ganglion.…”

“…After stimulation of the Edinger-Westphal nucleus, the parasympathetic signal is delivered by the oculomotor nerve to the superior orbital fissure of the eye and ciliary ganglion. The parasympathetic pupillary efferent signal stimulates the short posterior ciliary nerves that innervate the iris for pupil constriction [2,4,8,9]. Parasympathetic input for pupil constriction is balanced and controlled by sympathetic signals from the superior cervical ganglion for pupil dilatation.…”

“…Parasympathetic input for pupil constriction is balanced and controlled by sympathetic signals from the superior cervical ganglion for pupil dilatation. When the afferent and efferent pathways for pupil reactivity are intact in functional and structural processes, both pupils show equal sizes and brisk constriction responses when stimulated with bright light [2,4,8,9].…”