Volumetric SS-OCT imaging of human anterior vitreous structure

Abstract

Purpose : To perform in vivo enhanced three-dimensional visualization of anterior vitreous opacities in subjects of different ages using a swept source OCT (SS-OCT) system.

Methods : This cross-sectional observational study included 100 eyes of 50 volunteers (mean age: 40.0±19.3 yo; age range: 9-77 years). The anterior vitreous behind the crystalline lens was imaged with a prototype SS-OCT operating at 1 μm in an enhanced vitreous imaging mode. In addition, axial length, ocular scattering index, ocular aberrations and contrast sensitivity function were measured for each subject. 3-D volumetric data sets (300×300 A-scans) of the anterior segment and the vitreous covering 8×8 mm² central area were acquired and registered using Elastix software. Different contrast enhancing approaches were implemented to effectively map vitreous opacities. Static and dynamic vitreous structures were segmented using ImageJ software. The vitreous opacity volume was compared with the corresponding measurements of axial eye length, aberrations, intraocular scattering and contrast sensitivity function (VCTS test).

Results : The high sensitivity of our SS-OCT instrument allowed for visualization of the microstructure and anatomy of the anterior vitreous body. Volumetric data sets generated en-face projection images of vitreous opacities as depth color-coded maps of the vitreous (Fig. 1). The projections and cross-sectional images revealed liquefaction as well as scattering from well-organized opacified structures in the anterior vitreous. The number of hyper-reflective voxels behind the crystalline lens enabled determination of an opacification grade that was correlated with the age (r = 0.8182, P < 0.05).

Conclusions : A custom SS-OCT allows for visualization of in vivo microstructural changes of the vitreous body that were associated with age-related opacification. The proposed method can be used for objective clinical evaluation and management of vitreous-related diseases.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1. Projection OCT image of the anterior vitreous. The depth behind the posterior lens interface was color coded.