Optical coherence tomography assessment of structural changes in the optic nerve head and peripapillary retina in idiopathic intracranial hypertension

Abstract

Introduction. Reliable detection of papilledema is essential for establishing the diagnosis of Idiopathic Intracranial Hypertension (IIH). The ophtalmoscopic fundus examination of the optic nerve head (ONH) is a subjective measurement, limited by the examiner’s experience, the patient’s degree of collaboration and the optics of the ophthalmoscope, making it often unreliable in detecting early edema and in assessing initial improvements or worsening. The objective of the study was to assess the role of optical coherence tomography (OCT) in diagnosing and monitoring papilledema in IIH. Materials and methods. The study period consisted of 3 years (October 2014- October 2017) in which we evaluated how OCT parameters correlated with the clinical grading of the optic nerve head (ONH) edema according to the Frisén’s scale. We included 11 patients (6 adults and 5 adolescents aged 15 years and above) with recently diagnosed IIH in the University Emergency Eye Hospital and ‘Prof. Dr. Al. Obregia Psychiatry Hospital, Bucharest, Romania. Patients underwent clinical evaluation and OCT examination in the Retina Clinic, Bucharest, Romania. The measurements were compared to a group of 13 subjects with demographic characteristics similar to the study lot, without IIH (7 adults and 6 adolescents over 15 years). Results. The average retinal nerve fiber layer (RNFL) thickness in the study lot was 165.8 μm, (95% CI ± 33 μm) compared to 116 μm (95% CI, ± 4.3 μm) in the control group, P= 0.001. We demonstrated a significant difference between the average RNFL thickness correlated to papilledema severity (r=0.967, N=22, P = 0.001), with an average value of 117 μm (95% CI, ± 16μm) in case of mild edema, 165 μm (95% CI, ± 89μm), in moderate cases and 269 μm (95% CI, ± 31 μm) in severe cases. Conclusions. Fundal photographs and optical coherence tomography can be used with clinical assessment and other visual tests for the diagnosis of papilledema. Frisén grade determined by direct fundus examination was significantly correlated with OCT parameters reflecting optic nerve head edema. Following the peripapillary RNFL thickness over different check-ups provides a quantitative and sensitive measurement of changes in the papilledema.