Evaluation of the ocular features of individuals presenting signs of idiopathic intracranial hypertension on magnetic resonance imaging without papilledema

Objectives: To evaluate the ocular characteristics of patients with findings of idiopathic intracranial hypertension (IIH) on magnetic resonance imaging (MRI) without papilledema on fundus examination. Materials and Methods: The study included 98 eyes of 50 patients with IIH findings on brain MRI without papilledema on ophthalmologic examination (papilledema (-) group), 39 eyes of 20 patients with papilledema on ophthalmologic examination (papilledema (+) group), and 86 eyes of 43 healthy control individuals. All participants realized detailed ophthalmologic examination and optical coherence tomography imaging and choroidal parameters, optic nerve head assessment, and volumetric measurements of macular inner retinal layers were performed based on these images. Findings were noted according to the participants' MRI reports. To allow for the analysis of data from two eyes and eliminate binocular bias, the generalized estimating equations model was used for statistical analysis. Results: There were no differences between the groups in terms of age and gender. In the papilledema (-) group, the thicknesses of the peripapillary retinal nerve fiber layer (RNFL) were higher in the inferior and global than the control group, but lower than the papilledema (+) group except for the temporal quadrant (p<0.05). In the papilledema (-) group, the macular RNFL volume was higher in the parafoveal and total areas than the papilledema (+) and control groups (p<0.05). In the papilledema (-) group, the subfoveal choroidal vascularity index (CVI) was lower than the papilledema (+) group (p<0.05). In the peripapillary choroidal analysis, stromal, luminal, and total choroidal areas (CA) were increased in the papilledema (-) group than the papilledema (+) group in all quadrants except the temporal quadrant (p<0.05), with no difference observed between the two groups in the inferior quadrant luminal CA. In the papilledema (-) group, the CVI was decreased in all quadrants compared to the control group, except for the temporal quadrant (p<0.05). In MRI findings, optic nerve tortuosity was found to be more frequent in the papilledema (-) group than in the papilledema (+) group, whereas no significant differences were observed between the groups for other MRI findings (p<0.05). Conclusion: The results of our study suggest that subclinical peripapillary, macular, and choroidal changes may accompany MRI findings in the papilledema (-) group. Keywords: idiopathic intracranial hypertension, papilledema, optical coherence tomography, magnetic resonance imaging, choroidal vascularity index.