Global prevalence of asteroid hyalosis and projection of its future burden: a systematic review and meta-analysis

Asteroid hyalosis is defined by the presence of white, snowball-like non-crystalline vitreous opacities that move with the vitreous and appear to be anchored to its matrix. Asteroid hyalosis commonly occurs in the absence of other identifiable ocular abnormalities and is usually an incidental finding. The vitreous opacities are usually invisible to the patient and asymptomatic, but asteroid hyalosis can be a significant obstacle to the examination of the fundus. The prevalence increases dramatically with age. The aetiology is unknown. We systematically reviewed the literature for epidemiological data, qualitatively reviewed available studies, conducted meta-analyses with demographical stratifications, evaluated temporal changes and estimated the future prevalence using forecasting analysis. Nine eligible studies were identified with data on 104 569 individuals. The overall population prevalence of asteroid hyalosis was 0.75% (95% confidence interval: 0.39-1.21%); however, the prevalence was highly age-dependent, ranging from 0.27% (95% confidence interval 0.12-0.49%) in individuals aged 0-39 years and gradually increasing to 3.07% (95% confidence interval 1.90-4.50%) in individuals aged >= 80 years. Male gender was an additional risk factor (odds ratio 1.80, 95% confidence interval 1.32-2.45, p = 0.00017). The estimated global prevalence was 10.7 million subjects in year 1950, which is expected to increase to 41.5 million in year 2020 and 91.2 million in year 2100. The prevalence of asteroid hyalosis is relevant because it impacts the utility of diagnostic strategies, especially screening methods for conditions such as diabetic retinopathy.