Abstract
Purpose:
To provide quantitative object imaging to investigate the effects of papilledema in a multi-site clinical trial setting.The NEI sponsored Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) evaluated the efficacy of diet plus acetazolamide versus diet plus placebo in new patients with IIH and mild visual field loss. The accepted objective method for evaluating papilledema and monitoring the alterations in the optic nerve head, the Frisén scale, is a non-continuous grading based on descriptive features. High Definition Optical Coherence Tomography (HD-OCT) has the potential to provide continuous variable measurements which demonstrate structural changes in the optic nerve and retina due to papilledema.
Methods:
126 of 165 enrolled IIHTT subjects, prospectively evaluated with standard automated perimetry, Frisén grading of photos, and high and low contrast visual acuity, had OCT imaging, using the Cirrus HD-OCT. OCT data were analyzed using the proprietary and custom 3-D segmentation algorithms to calculate retinal nerve fiber layer (RNFL), total retinal thickness (TRT), optic nerve volume (ONHV), and retinal ganglion cell layer (GCL) measurements. Results for ‘study eyes’ (with worse perimetric mean deviation) were used for most analyses.
Results:
At study entry, OCT parameters of swelling, RNFL, TRT, and ONHV were increased in both eyes and all measures had strong (r >0.8) significant correlations for interocular comparisons and among all parameters. Of 126 study eyes, only 9 had GCL thinning (also with worse vision testing results). All OCT parameters of swelling showed a strong (r > 0.76) correlation with Frisén grade and mild (r > 0.24) but significant correlation with lumbar puncture opening pressure. For all eyes, neither visual acuity (high or low contrast) nor mean deviation of the field correlated with any OCT measure of swelling or GCL thinning.
Conclusions:
OCT provides continuous variables and quantified assessment on the effects of papilledema. In early IIH, the severity of papilledema does not correlate with vision loss. The low frequency of early GCL loss suggests that vision field and low contrast acuity loss should be reversible with treatment in most cases.
Keywords: 627 optic disc •
613 neuro-ophthalmology: optic nerve •
610 nerve fiber layer