Widefield Whole Eye SSOCT Measurement of Retinal Curvature for Screening of Elevated Intracranial Pressure

Abstract

Purpose : Magnetic resonance imaging (MRI) can visualize posterior eye flattening in the presence of elevated intracranial pressure (ICP). In contrast to MRI, optical coherence tomography (OCT) is a more common and available ocular imaging technique. We used a custom whole eye OCT system that provides simultaneous wide fields of view of the anterior and posterior eye to measure posterior eye flattening as an additional sign for non-invasively identifying elevated ICP.

Methods : We developed a custom whole eye swept-source (λ₀=1045nm; 100 kHz) OCT system to simultaneously image both the anterior and posterior eye in a single volume. Six subjects (N = 11 eyes) seen in the Duke neuro-ophthalmology clinic with elevated ICP were imaged with whole eye OCT under an IRB approved protocol. For morphometric analysis, we segmented OCT volumes to obtain subject distance from imaging system, ocular axial length, and the location of the retinal pigment epithelium (RPE, Fig. 1A). These parameters were corrected for system and subject optical distortions to obtain the radius of curvature (R_c) of the retina. MRI (Fig. 1B) and lumbar punctures (LP) were performed as part of the subjects’ standard of care prior to OCT imaging. Three control subjects (N = 6 eyes) were imaged for comparison to the high ICP group using Wilcoxon tests. Because OCT was performed after LP in subjects with elevated ICP, we compared the high ICP population to the controls for each modality.

Results : Curvature, R_c, measured by OCT (10.72±0.64mm) was not significantly different from MRI (10.49±0.35mm) in the control population (paired p = 0.57). For the elevated ICP population, the measured curvature was significantly different from controls for both modalities – high ICP OCT: R_c = 14.58±2.41mm, p = 0.004 and high ICP MRI: R_c = 33.71±15.24mm, p = 0.001.

Conclusions : We have demonstrated a readily available imaging method (OCT) for assessing ocular flattening in subjects with elevated ICP. This offers the potential opportunity to non-invasively monitor longitudinal changes in a patient’s ICP during treatment.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

A) Whole eye OCT from right eye of subject with elevated ICP. Slice from repeated radial volume. RPE of retina segmented. B) MRI from right eye of same subject.