n.spots before the eyes caused by opaque cell fragments in the vitreous humor and lens
同义词：musca volitansfloaterspots
英汉双解大词典
muscae volitantes/ˈmʌsiː vɒlɪˈtæntiːz/
1.
N-PLURAL（复数型名词）
moving black specks or threads seen before the eyes, caused by opaque fragments floating in the vitreous humour or a defect in the lens 飞蝇症 [pathol]