Abstract
Purpose:
To investigate the relationship between changes in intracranial pressure (ICP) with changes in ocular pulse amplitude (OPA) in idiopathic intracranial hypertension (IIH) patients. The purpose of this study was to evaluate whether a reduction in ICP through drainage of cerebrospinal fluid (CSF) during a lumbar puncture (LP) leads to a change in OPA.
Methods:
Subjects were recruited through presentation with symptoms of headache, visual disturbances, and possibly the presence of papilledema upon slit lamp examination. If an LP was ordered for diagnostic purposes, then ocular pulse pressure waveforms were obtained in the supine position immediately before and after LP. A contact lens with an embedded sensor from the PASCAL Dynamic Contour Tonometer (DCT) or modified Perkins handheld tonometer with a DCT tip, both supplied by the manufacturer (Ziemer, Port, Switzerland), was used to measure intraocular pressure (IOP) and OPA. Systemic blood pressure was acquired, with systolic, diastolic, and the difference of the two, referred to as pulse pressure (PP), being noted. Opening and closing pressures of the LP were also recorded; the difference between CSF pressures was used as a surrogate for the change in ICP. The lack of closing pressure caused exclusion of 2 subjects, leaving a total of 7 right eyes of 7 subjects with 1 suspected IIH patient and 6 known IIH patients with recurring symptoms. Regression analyses were performed to determine relationships between pre and post LP data in terms of ΔIOP, ΔOPA, ΔIOP/OPA, ΔICP, and ΔPP.
Results:
No relationship was found between ΔICP and ΔOPA. However, there was a significant relationship between ΔICP and ΔIOP/OPA (r2= 0.8072; p= 0.0383). This was due to the linear relationship between IOP and OPA, such that if IOP increases then OPA increases. There was no significant relationship between ΔICP and ΔPP. Thus, the findings demonstrated a significant correlation between ΔICP with ΔIOP/OPA before and after LP, indicating a change in OPA as ICP is decreased.
Conclusions:
Anatomically, the results imply that peaked ICP waves due to increased ICP are transmitted from the cerebrospinal fluid surrounding the optic nerve into the eye itself, influencing OPA. Clinically, the results also indicate that IOP/ OPA may be a parameter that clinicians can use to monitor changes in ICP non-invasively in IIH patients.
Keywords: 568 intraocular pressure •
612 neuro-ophthalmology: diagnosis