What causes an opaque grey floater in the eye?

An opaque grey floater in the eye is often caused by changes in the vitreous gel, which is the clear substance filling the eye. As we age, the vitreous can become more liquid and shrink, leading to the formation of clumps or strands that cast shadows on the retina, resulting in floaters. In some cases, these floaters can indicate more serious conditions, such as retinal tears or detachments, so it's important to consult an eye care professional if they appear suddenly or are accompanied by other visual disturbances.