Comparison of Pupilometer and Ultrasound of Optic Nerve Sheath Diameter in Estimating Intracranial Pressure (ICP)

Comparative Analysis of Pupilometer and Ultrasound Assessment of Optic Nerve Sheath Diameter in Estimating Intracranial Pressure (ICP)

The purpose of this investigator-initiated study is to compare the use of pupilometer and ultrasound assessment of optic nerve sheath diameter in predicting the ICP and to see if there is a value that could be used to indicate elevated ICP with either modality as these numbers are inconsistent throughout the literature. Patients that have either an external ventricular drain (EVD) or bolt placed will be enrolled in the study. After the EVD and bolt are placed the patient will undergo pupilometer examination (standard of care) followed by ultrasound assessment of the optic nerve sheath diameter (ONSD). The three values will be recorded. The same patient may have multiple readings performed if there is a change in ICP either spontaneously or due to intervention.

Inclusion Criteria:

• Age greater than or equal to 18 years old
• Intracranial pathology requiring either EVD or bolt placement for ICP measurement

Exclusion Criteria:

• Known disorder of lens or orbit including but not limited to glaucoma, cataract, blindness, lens implants.
• Patients unable to close eyelids as this would increase risk of corneal abrasion from ultrasound probe.