As we get older, the gel in the middle of eye, known as the vitreous, starts to degenerate and break down; a process known as posterior vitreous detachment or PVD. As this occurs, opacities can form within the gel, which cast a tiny shadow on the back of the eye or retina. These shadows are what we see as floaters, and they can take many shapes – spots, lines, squiggles etc. As these floaters are sitting in the vitreous gel, when we move our eye the floaters move around the gel, and therefore seem to move around in front of our vision. While these floaters can be annoying, they do tend to become less noticeable over time.

As the vitreous degenerates, it also collapses towards the centre of the eye. In some people, the vitreous has firm attachments to the surrounding retina, and when it collapses, exerts traction on the retina. This traction irritates the retina, producing what is perceived as a flashing light.

In most cases, the attachment between the retina and vitreous will separate, usually over a few weeks, and the flashing lights will stop. In a small percentage of people however, the vitreous does not separate from the retina, and instead pulls on the retina and produces a tear in the retina. This is important as the tear provides an access point for fluid in the vitreous to pass through the tear, and go under the retina, producing what we call a retinal detachment. A retinal detachment is an urgent sight threatening condition, which needs to be treated with surgery relatively quickly.

Fortunately if a tear is detected, a retinal detachment can be prevented by performing laser around the tear. By creating a barrier around the tear, laser prevents fluid from being able to get under the retina.

Flashes and floaters are very common, but there is no way of knowing if you have a retinal tear without a proper dilated retinal examination. If you have flashes and/or flashes, it is important to see your ophthalmologist as soon as possible for a full retinal check.