Assessment of eccentric vitreous density in healthy subjects using optical coherence tomography

Abstract

Purpose : Optical coherence tomography (OCT) is widely used to perform quantitative assessment of retinal anatomy. It is accepted as an essential tool for diagnosis and monitoring of central retinal pathology and analysis of retinal nerve fibre layer thickness at the optic disc. Our group has previously demonstrated OCT as a novel modality in the assessment of vitreous haze in patients with uveitis and more recently developed and validated custom software to enable automated analysis of vitreous signal intensity (VITAN - VITreous ANalysis). We now wished to employ this software to examine the vitreous of healthy controls in a range of intra-ocular locations.

Methods : Twenty healthy individuals with no past history of ocular disease were included in this analysis. Images were acquired using the Heidelberg Engineering Spectralis spectral domain OCT scanner. For each patient, bilateral retinal images were acquired in the primary position (to examine central vitreous), up gaze (superior vitreous), down gaze (inferior vitreous) lateral gaze (temporal vitreous), and medial gaze (nasal vitreous). Three images were acquired in each position of gaze, and mean vitreous gel signal intensity calculated for each location using our VITAN software. Vitreous density was standardized against RPE density to control for potential lens opacity. Vitreous density was compared between each of the five imaging locations by one-way ANOVA repeated measures and Tukey post-test for multiple comparisons.

Results : Whilst variation was observed between individual patients, spectral domain OCT scanning demonstrated significant differences in mean vitreous density throughout the locations tested, being most dense inferiorly and least dense centrally. Using the central vitreous as a comparator, relative vitreous densities were 1.36 nasally, 1.47 temporally, 1.80 superiorly and 2.16 inferiorly. Inferior vitreous density was significantly greater than central, temporal and nasal locations (p<0.01 for all comparisons).

Conclusions : Spectral domain OCT scanning combined with our VITAN software has revealed variation in vitreous density across different intra-ocular locations in healthy subjects. Such anatomical variation has not previously been reported. This pilot study highlights a novel anatomical feature in healthy patients, and further demonstrates the potential utility of OCT scanning in quantitative assessment of the vitreous gel.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.