Diagnostic value of optical coherence tomography for intracranial pressure in idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH) is a condition of raised intracranial pressure (ICP) in the absence of space-occupying lesions or other known etiology. It primarily affects young obese females, and potentially causes permanent visual loss due to papilledema and secondary optic atrophy. The aim of this study was to evaluate the diagnostic value of optical coherence tomography (OCT) as a marker for CSF opening pressure in patients with idiopathic intracranial hypertension (IIH). We conducted a case-control study of 20 newly diagnosed, 21 long-term IIH patients, and 20 healthy controls. Investigations included measurement of peripapillary retinal nerve fiber layer thickness (RNFLT) and total retinal thickness (RT), automated visual field testing, and measurement of CSF opening pressure. An OCT elevation diagram was developed as a new diagnostic tool. The diagnostic ability of OCT as a marker of increased ICP (> 25 cmH(2)O) was investigated using multiple regression and receiver operating characteristic (ROC) curves. OCT elevation diagrams showed that in 60 % of patients newly diagnosed with IIH and in 10 % of patients with long-term IIH, 50 % or more of the OCT scans (RT and RNFLT) were above normal. The percentage of abnormal OCT scans was significantly associated with increased ICP (p < 0.0001). Estimated areas under the ROC curves increased from 77.1 to 86.9 by including OCT in multiple regressions. Autoperimetry pattern standard deviation was significantly increased (p = 0.0005) and mean deviation was significantly decreased (p = 0.0005) in IIH patients as compared to healthy controls. Increased peripapillary retinal thickness measured by OCT is associated with increased ICP in newly diagnosed IIH patients. OCT may thus serve as a valuable supplement to subjective assessment of papilledema in patients suspected of having IIH. In long-term IIH patients who have previously been treated, OCT appears to be of limited value in predicting ICP.