Purpose : To characterize age-related changes in anterior vitreous with 3-D high-resolution Swept Source Optical Coherence Tomography (SS-OCT) and evaluate associations with vision.
Methods : This cross-sectional observational study included 49 phakic eyes of 49 patients (25 men and 24 women, mean age: 40.0 ± 19.3 yrs, range: 9-78 yrs). The anterior vitreous and the crystalline lens were imaged with a prototype SS-OCT operating at 1 μm in an enhanced vitreous imaging mode. OCT-derived parameters were: Vitreous Optical Density (VOD), Vitreous Opacification Ratio (VOR), and Lens Optical Density (LOD). Axial eye length (AL) was measured with optical biometry. Retinal point spread function was measured with a double-pass system to obtain objective scatter index (OSI). Contrast sensitivity was measured using a visual simulator, and area under log-log contrast sensitivity function (AULCSF) was calculated.
Results : The high sensitivity SS-OCT instrument allowed for visualization of the anatomy of the anterior vitreous body including gel vitreous, lacunae of liquefied vitreous, Berger’s space, retrolental laminar structures, and fibrous opacified structures. VOD, VOR, and LOD showed high reproducibility (intraclass correlation coefficients 0.968, 0.975, and 0.998, respectively). VOD was highly correlated with VOR (Pearson’s R=0.96, p<0.000001). VOD, VOR and LOD correlated with age (R=0.48, 0.58, and 0.85; p<0.001 for each). VOR and LOD correlated with OSI (R=0.36; p=0.0094, and R=0.3630, p=0.0096, respectively). Furthermore, VOR negatively correlated with AULCSF (R=-0.53, p<0.00009). Multivariable regression confirmed a strong independent association between age and LOD, which seemed to mediate the relationships between age and VOD or VOR. AULCSF was linked to OSI.
Conclusions : SS-OCT enables visualization of age-related microstructural changes of the anterior human vitreous. Opacification of the anterior vitreous is associated with increased heterogeneity, and more scattering with degradation in contrast sensitivity function. While anterior vitreous opacities might induce CSF degradation, this more likely reflects central and posterior vitreous opacification, and can thus serve as a useful index for management of vision degrading myodesopsia.