Abstract
Purpose :
Asteroid Hyalosis (AH) is characterized by yellowish-white, round structures in vitreous composed of lipids complexed with calcium, phosphates, and O2 (Khoshnevis et al: Surv Ophthalmol 64:452-62, 2019). It is commonly believed that the smooth spherical structures of AH do not disturb vision, but to date only visual acuity has been assessed. This study explores the relationship between AH and contrast sensitivity (CS).
Methods :
AH was diagnosed in 45 eyes of 41 patients (19♂ & 21♀), 17 who chose vitrectomy (PPV; age = 72.6 ± 7.5 yrs), and 28 who elected observation (OBS; age = 70.4 ± 5.5 yrs). Posterior vitreous detachment (PVD) was present in 9/17 (53%) PPV eyes and 17/28 (60%) OBS eyes. Quantitative ultrasonography (QUS) measured vitreous density with a clinical scanner (Lumibird/Quantel, France) and a 15 MHz probe (AVISO) as previously described (Mamou et al: IOVS 56:1611–7, 2015). CS was measured using Freiburg Acuity Contrast Testing, where higher %W = worse CS.
Results :
Vitreous echodensity was over 10-fold greater in AH subjects (mean = 9031 AU) than previously observed in non-AH patients with floaters (815 ± 217 AU in myopic eyes, 613 ± 159 AU in non-myopes; Nguyen et al: AJO 224:246-53, 2021). QUS was even greater in AH patients who chose vitrectomy (13578 ± 3093 AU) than observation (6270 AU; p < 0.0001). While visual acuity was normal and no different in PPV (20/35) than OBS subjects (20/30), CS was worse in subjects with AH who chose vitrectomy (6.82 ± 2.30 %W) than OBS (3.68 ± 1.50, p < 0.0001). In all AH subjects, there was worse CS with increasing vitreous echodensity: R = 0.63, p = 0.00003 (see figure). Post-operatively, both QUS and CS improved: QUS by 94%, p < 0.0001; CS by 44%, p < 0.0001.
Conclusions :
AH is associated with increased vitreous density that is 10-fold greater than in non-AH patients with floaters. Moreover, increased vitreous echodensity is even greater in AH patients who chose vitrectomy than in those who chose observation. Although this study confirmed that visual acuity is largely unaffected by AH, there is profound degradation in contrast sensitivity, which substantially improves following vitrectomy. Although previous hypotheses postulated that light scattering by the smooth spherical surfaces of asteroid bodies is not as disturbing to vision as intravitreal collagen aggregates in myopia and aging (PVD), that appears to only be true for visual acuity, since contrast sensitivity is severely degraded by AH.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.