Optical Coherence Tomography Visualization of Optic Nerve Head Structure Detects Acute Changes in the Intracranial Pressure (P2.293)

OBJECTIVE: To determine whether dynamic changes in optic nerve head (ONH) structure, as measured by high definition optical coherence tomography (HD-OCT), occur immediately after lowering intracranial pressure (ICP). BACKGROUND: Biomechanical changes in the ONH with sustained elevation in ICP are well-established. However, the time course of structural changes in ONH with elevated ICP has not been studied. It is not known whether acute ICP changes will cause dynamic measurable changes in the ONH. HD-OCT allows in-vivo enhanced depth imaging of papillary sub-structures. DESIGN/METHODS: We conducted a prospective pilot study in 5 female patients with idiopathic intracranial hypertension (IIH) undergoing a clinically indicated lumbar puncture (LP) after IRB approval. The Cirrus HD-OCT (Carl Zeiss Meditec) was positioned to acquire images in the lateral decubitus position. Optic disc cube 200x200 and HD5 Line Raster scans centered on the ONH were obtained immediately before and after draining cerebrospinal fluid (CSF) in the left lateral decubitus position. Retinal nerve fiber layer (RNFL) thickness, peri-papillary retinal pigment epithelium/bruch’s membrane (RPE/BM) angulation, transverse diameter of neural canal at level of RPE/BM, and highest vertical point of internal limiting membrane (ILM) from transverse diameter were measured. Descriptive statistics are presented. RESULTS: The mean opening and closing CSF pressures were 31.6±11.8 and 11.6±3.3 cmH2O, respectively. Average RNFL thickness decreased after LP in all subjects (mean; pre LP: 151±71µm; post LP: 129±40µm). The mean decrease in average RNFL thickness was 32±36µm. The neural canal diameter (mean; pre LP: 1985±559µm; post LP: 1590±228 µm) and RPE/BM angulation (mean change; 5.8±2.0 degrees) decreased in all subjects. A decrease in papillary height was seen in 3 of 5 subjects (mean; pre LP: 976±274 µm; post LP: 938±300 µm). CONCLUSIONS: There is an acute change in ONH biomechanical parameters with change in ICP in IIH patients. A larger prospective study is needed to determine the utility of OCT as a non-invasive method for monitoring ICP. Disclosure: Dr. Anand has nothing to disclose. Dr. Pass has nothing to disclose. Dr. Calvillo has nothing to disclose. Dr. Tang has nothing to disclose. Dr. Cajavilca has nothing to disclose. Dr. Urfy has nothing to disclose. Dr. Suarez has nothing to disclose. Dr. Rao has nothing to disclose. Dr. Bershad has nothing to disclose.