Baseline OCT measurements in the idiopathic intracranial hypertension treatment trial, part II: correlations and relationship to clinical features

Abstract

Purpose: The accepted method to evaluate and monitor papilledema, Frisén grading, uses an ordinal approach based on descriptive features. Part I showed that spectral-domain optical coherence tomography (SD-OCT) in a clinical trial setting provides reliable measurement of the effects of papilledema on the optic nerve head (ONH) and peripapillary retina, particularly if a 3-D segmentation method is used for analysis.(1) We evaluated how OCT parameters are interrelated and how they correlate with vision and other clinical features in idiopathic intracranial hypertension (IIH) patients.

Methods: A total of 126 subjects in the IIH Treatment Trial (IIHTT) OCT substudy had Cirrus SD-OCT optic disc and macula scans analyzed by using a 3-D segmentation algorithm to derive retinal nerve fiber layer (RNFL) thickness, total retinal thickness (TRT), retinal ganglion cell layer plus inner plexiform layer (GCL+IPL) thickness, and ONH volume. The SD-OCT parameter values were correlated with high- and low-contrast acuity, perimetric mean deviation, Frisén grading, and IIH features.

Results: At study entry, the average RNFL thickness, TRT, and ONH volume showed significant strong correlations (r ≥ 0.90) with each other. The same OCT parameters showed a strong (r > 0.76) correlation with Frisén grade and a mild (r > 0.24), but significant, correlation with lumbar puncture opening pressure. For all eyes at baseline, neither visual acuity (high or low contrast) nor mean deviation correlated with any OCT measure of swelling or GCL+IPL thickness.

Conclusions: In newly diagnosed IIH, OCT demonstrated alterations of the peripapillary retina and ONH correlate with Frisén grading of papilledema. At presentation, OCT measures of papilledema, in patients with newly diagnosed IIH and mild vision loss, do not correlate with clinical features or visual dysfunction. (ClinicalTrials.gov number, NCT01003639.).

Keywords: OCT; intracranial hypertension; lumbar puncture; papilledema.

Figure 1

There was general agreement between the reading center and the clinical site investigators in the staging of papilledema, using the Frisén scale. The most frequent grades of papilledema were 2 to 4.

Figure 2

Scatter plots for OCT measures in study eyes, using Pearson correlations. Top of figure shows frequency distribution histogram for all parameters. GCL, GCL+IPL average thickness for the macular region; Line 3, ONH height measured by using Line 3 of the SD raster lines; N, number of study eyes with data for each OCT measure; ONH, total optic nerve head volume; p(r) = P value; Zeiss, percentile Zeiss controls.