The effects of aging vitreous on contrast sensitivity function

Contrast sensitivity function (CSF) declines with age. When unassociated with cataracts, this is hypothesized to be due to macular ganglion cell complex (GCC) thinning. However, other studies found associations with increased vitreous echodensity and posterior vitreous detachment (PVD). We investigate the relationship between CSF, vitreous echodensity, PVD, and GCC thickness as related to age in the same subjects.

Age, CSF (Weber index: %W), vitreous echodensity (quantitative ultrasonography [QUS]), lens status (phakia or pseudophakia), best-corrected visual acuity (BCVA), and GCC thickness (SD-OCT) were evaluated in 57 eyes of 57 subjects with (n = 32, mean age = 62 years) and without (n = 25, mean age = 44 years) PVD (P < 0.001). A multivariate linear regression analysis was performed to assess the effects of independent variables on CSF.

CSF was 51.2% worse in eyes with PVD (2.98 ± 0.31 %W) compared to no PVD (1.97 ± 0.24 %W; P < 0.001). QUS was 55.8% greater in eyes with PVD than those without (P < 0.001). Among all subjects, PVD status, vitreous echodensity, and age were the only independent variables demonstrating significant effects on CSF. Lens status, BCVA, and GCC thickness did not demonstrate association with CSF.

PVD, vitreous echodensity, and age are determinants of CSF. PVD and increased vitreous echodensity are each associated with diminished CSF, independent of age. Thus, in the absence of GCC thinning and cataracts, vitreous changes may be a cause of decreased CSF with age.