Clinical Implications of Quantitative Infrared Pupillometry in Neurosurgical Patients

Abstract

Pupillometry has been widely employed in the evaluation of a large number of pathological conditions, including intracranial pathology. The recent introduction of a portable, user-friendly, infrared pupillometer (ForSite, NeurOptics Inc., Irvine, CA) has enabled the accurate and reproducible measurement of several pupillary parameters, such as maximum and minimum apertures, constriction and dilation velocities, and latency period. It should be noted that various clinical conditions, especially neurological and ocular diseases, as well as numerous medications, may interfere with the measurements. Furthermore, a number of physiological parameters, such as the intensity of retinal illumination, the level of patient's alertness, the intensity of ambient light, as well as the time of day that the examination is performed may alter the obtained values. The potential implications of pupillometry in the clinical assessment of neurosurgical patients, including its complex relationship to intracranial pressure changes, mandate the undertaking of prospective clinical studies validating the clinical significance of this noninvasive, diagnostic modality.

Noninvasive Assessment of Cerebrospinal Fluid Pressure

“…28 Furthermore, it is unclear whether the initial findings in head trauma will translate to other causes of increased ICP.…”

Interrater Reliability of Pupillary Assessments

“…Next, a burst (0.8 s) of light is emitted at a fixed distance from the patient and a high-speed video recording of the pupillary response is used to measure the maximum pupil size, minimum pupil size, constriction velocity and neuro pupillary index (NPi TM ) [20]. Automated pupillometry may reduce observer bias and provide insight to intracranial pathology [21,22]. However, three citations, a case study [23], a study of healthy volunteers receiving phenylephrine versus sterile water [24], and an interrater reliability including only nurse examiners find limitations in pupillometry [25].…”

Exploratory study comparing dysautonomia between asthmatic and non-asthmatic elite swimmers

“…Though, it must be highlighted as a strength of our study, that a highly controlled evaluation was performed for all variables known to possibly interfere with the pupillometry. 8 Also, this is the first study to address the question of dysautonomia assessed by pupillometry related with swimmers asthma and AHR. Previous studies using this method to evaluate autonomic nervous system have not addressed the relationship with bronchial outcomes.…”

“…The first visit was in the morning (from 8 to 11 am) because of the circadian rhythm of the size of the pupil. 8 Medical history and potential medication were reviewed to determine eligibility. The eligible ones answered a structured questionnaire, and performed pupillometry, spirometry and skin prick testing.…”