Effects of Age and Vitreous Structure on Contrast Sensitivity

Abstract

Purpose : Contrast sensitivity (CS) declines with age, but the mechanism is not fully elucidated. Diminished CS has been associated with increased vitreous echodensity on quantitative ultrasonography (QUS; Mamou et al. IOVS 2015;56:1611-7) and decreased macular ganglion cell complex (GCC) thickness (JNO 2013;33(2):137-42). This study evaluated the relationship between vitreous echodensity, posterior vitreous detachment (PVD), GCC thickness, and CS as related to age. We tested the hypothesis that both PVD and increasing vitreous echodensity are associated with decreased CS.

Methods : One eye of 38 subjects with (n=15) and without (n=23) PVD (ultrasound diagnosis) had CS measured with Freiburg Acuity Contrast Testing (Weber index, %W; lower values indicate better CS). QUS was performed longitudinal to the macula to quantify acoustic scattering (Energy). GCC thickness in 5 locations in the papillomacular bundle was measured 1.5 mm from the fovea with optical coherence tomography. As a control, CS was further compared in a subgroup of 23 age-matched subjects; 9 with PVD (mean age 52.4 ± 2.79 years) and 14 without PVD (mean age 47.4 ± 1.5 years; p=0.104).

Results : Except for the age-matched subgroup, mean age was significantly different between subjects with PVD (60.5 ± 3.4 years) and those without PVD (43.0 ± 2.1 years; p<0.001). Mean CS was 53.9% worse (p<0.001) in eyes with PVD (2.97 ± 0.26 %W) compared to those without PVD (1.93 ± 0.13 %W), corresponding to a large effect size (Cohen’s d=1.26). Subjects with PVD had worse CS with increasing age (Fig 1; r=0.622, p=0.013), whereas those without PVD showed no such correlation (p=0.553). Increasing age was correlated with increasing vitreous echodensity in subjects with PVD (r=0.656, p=0.008), but not in those without PVD (p=0.387) (Fig 2). Mean GCC thickness was not correlated with either CS (p=0.354) or age (p=0.832). In the age-matched control subgroup there was still a 33.9% diminution in mean CS (effect size d=1.02) in eyes with PVD versus those without PVD (p=0.022).

Conclusions : PVD is associated with worse CS, independent of age. CS declines linearly with age in individuals with PVD but not in those without PVD. Individuals with PVD also experience progressive increase in vitreous echodensity with age, but those without PVD do not. Thus, there are structural and visual effects associated with PVD that worsen with increasing age, and in our patients age-related GCC thinning was not found.

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