Normally, light has a unobstructed journey from the lens to the retina. Any objects in the vitreous humour will cast shadows on the retina, obscuring your vision.
Causes of eye floaters
Click to Enlarge
Floaters are caused by small pieces of debris that float in your eye. They occur between your lens and retina, actually inside your eye. The lens is a small, clear structure that focuses light as it enters the eye. The retina is the light-sensitive tissue lining the inside surface of the back of the eye.
Your eye is full of vitreous humour, which is a clear, jelly-like substance that fills the space in the middle of the eyeball. It is 99% water and it is here that you’ll find the debris that causes floaters.
Floaters occur naturally as you age. Some people may have posterior vitreous detachment (PVD), where the vitreous jelly comes away from the retina. This may cause a sudden increase in the number of floaters.
Causes of vision flashes
Flashes occur when the retina is manipulated in some way. This can be by the vitreous jelly as is pulls away from the retina through PVD, or as a results of a retinal tear. If the cause of the floaters is PVD, they may well be accompanied by flashing lights.
How aging affects your eyes
As you get older, the vitreous humour in your eyeball becomes softer, making the collagen in your eye more visible. As you move your eye, you might be able to detect the collagen as a swirling pattern on your vision. This is a perfectly natural cause of eye floaters and is common in people in their 60s and 70s.
Around three quarters of people over 65 suffer from PVD. As your eye ages, the central part of the vitreous humour becomes more liquid, and the outer part, the cortex, starts to shrink away from the retina. Eye floaters develop as the collagen clumps together enough to become visible.
As the jelly-like humour pulls at the retina as it withdraws, it stimulates the retina, causing your brain to believe that there is a flashing light present. This is what causes the sensation of flashing lights.
Retinal Tears & Retinal Detachment
Around 50% of people have the vitreous humour separated from their retina by the time they’re 50. In some cases, this process can cause the delicate blood vessels in the eye to burst and bleed into the vitreous humour. This manifests as darker dots on your vision.
In other cases, the jelly-like vitreous humour remains attached to the retina in parts and causes worse tears as it comes away. In this case, retinal pigment cells bleed into the humour, causes a sudden shower of floaters and sometimes even bursting flashes like lightning strikes.
Visit Eyesite Today
Floaters and flashes do not usually cause long term impairment to your vision. However, they could be an indicator of a more serious condition. Retinal tears can lead to full retinal detachment.
We recommend that if you experience new floaters and flashes that you visit your local Eyesite branch and book an examination with one of our expert optometrists with some degree of urgency.