Flashes & Floaters
Flashes & Floaters


This page provides the information you need to help you understand retinal detachment, how it is treated and how it may affect your vision.

A retinal detachment is a medical emergency and if it is not assessed and treated you may lose all the vision in the affected eye.

Retinal detachment occurs when the retinal layers, specifically the sensory retina, separates from the retinal pigment epithelium rather like wallpaper peeling off a damp wall. The retina needs to be attached to the pigment epithelium to survive and work properly, so if a retinal detachment is not detected and treated quickly it can result in the loss of some or all the vision in your eye.

If you have a sudden onset of any of the symptoms associated with retinal detachment such as floaters, flashing lights and/or a dark shadow across your vision in one or both eyes, you should see your eye health care professional as soon as possible.

How your eye works

When you look at something, light passes through the front of your eye, and is focused by the lens onto your retina. The retina is a delicate tissue that coats the inside of your eye. The retina converts the light into electrical signals that travel along the optic nerve to your brain. The brain interprets these signals to "see" the world around you. The retina is made up of different layers. The sensory retina contains the light sensitive cells and its supporting layer is made up of the retinal pigment known as epithelium. The retina is also supplied with blood by a delicate network of blood vessels on its surface.

Light is focused onto a tiny area of the retina called the macula, which is about the size of a pinhead. This highly specialised part of the retina is vital, because it enables you to see fine detail when you are looking directly at something such as words, photos or the television. Your macula also gives you much of your ability to see colours. The rest of the retina, gives you side vision (peripheral vision). The eye is filled with a clear substance called the vitreous gel. Light passes through the gel to focus on the macula.


Most retinal detachments happen because a tear or hole in the retina allows fluid to leak between the retinal layers and this then causes the retina to detach. Holes in the retina can occur because of changes that happen as you age, whereas tears happen because the retina has been pulled and torn. Tears can be caused for example, by a blow to the head or if the vitreous gel suddenly becomes detached from the retina (known as acute posterior vitreous detachment or PVD - most gradual PVD does not result in retinal detachment). Retinal detachment caused by holes or tears is called Rhegmatogenous.

Other eye conditions such as diabetic retinopathy can result in fibrous scar tissue forming inside the vitreous and on the surface of the retina. This scar tissue can then pull on the retina (traction) causing a detachment. This type of traction on the retina can also cause tears that allow the fluid to leak in between the layers, again causing a detachment. This type of retinal detachment is called Tractional.

Fluid from the vessels behind the retina can also leak between the retinal layers. This is a less common cause of detachment and happens because of another condition such as an inflammation or tumour. This type of retinal detachment is called Exudative.


Rhegmatogenous retinal detachment is the most common form of retinal detachment and is still very rare. It only occurs in about 1 in 10,000 people each year. Retinal detachment can happen to someone of any age but is very rare under the age of sixteen and most commonly happens to people aged between 60 and 70 years.

Most retinal detachments occur because of a tear in the retina. A common cause of tears is a complete or acute posterior vitreous detachment . This happens when the vitreous gel filling the eye liquifies and collapses. Changes to the vitreous gel are very common in older people, occurring in 60 per cent of people over 70 years of age. For the vast majority of people these changes do not result in any serious complications. For more information, go to our pages on Posterior vitreous detachment. In a small number of cases the pulling away of the vitreous causes a retinal tear and in some cases this can lead to a retinal detachment.

The retina changes as you age and at its edges it can develop holes and weakened areas. These holes can, in some cases, lead to detachment. Holes are far less likely to lead to a detachment than a retinal tear. You have an increased risk of retinal detachment if you:

  • are very short sighted (more than minus 6.00 D)
  • have had a trauma (injury or blow) to the eye
  • already have had a detachment in one eye, then there is an increased likelihood of a detachment in the other eye. Between 2 and 10 per cent of detachments occur in both eyes)
  • have a family history of retinal detachment.

Symptoms that warn of a retinal detachment

Flashing lights

Many people experience flashing lights, most commonly around the edges of their vision. Flashing lights occur when the retina is stimulated by something within the eye rather than by the light entering the eye. They are often caused by the vitreous gel inside the eye moving and pulling on the retina.

In many cases flashing lights are caused by a gradual vitreous detachment and in most cases this doesn't cause any long term problems with your vision. However, flashing lights can indicate that there is a tear in the retina. There is no way you can tell whether your flashing lights are caused by your vitreous or by a retinal tear. If you suddenly experience flashing lights you should have your eye examined by an optometrist (optician) as soon as possible, usually within 24 hours.


Floaters are caused by debris in the vitreous casting a shadow on the retina. The brain then sees this as an object floating around in space. Floaters are very common and most people can expect to have a few as they get older. People who are short sighted or have had eye operations in the past often have more floaters. Floaters can take many shapes being described as rings, spiders' legs or cobwebs. They are not in themselves a cause for concern especially if you have had them for months or years.

However, if you experience a recent dramatic increase in the number of floaters or notice showers of dust-like floaters, this could be a sign that changes are happening at the back of your eye.

If you experience a recent onset of floaters or change to the nature or numbers of your floaters, you should have your eyes examined by an optometrist as soon as possible usually within 24 hours.

Dark shadow


If your retina does detach then it can't work properly anymore. You will see this as a dark shadow in the corner of your vision. If more of your retina detaches then the shadow will move towards the centre of your vision.

If you experience a dark shadow moving up, down or across your vision you need to attend your local eye clinic as soon as possible within the same day if possible or within 24 hours.

Blurring of vision

Your vision can gradually become blurred for many reasons and a visit to the optometrist will help you find out why. If your vision suddenly becomes blurred, especially if any of the other symptoms of flashing lights, floaters or a shadow are present, then this is more serious, and you need to consult your optometrist as soon as possible and usually within 24 hours.

Many people have flashes and floaters and this is normal for their eye. Not every person with flashes and floaters will develop a retinal detachment. However, if you do experience flashes or floaters for the first time, or your usual flashes and floaters change, then you should have your eyes examined.

If you experience a dark curtain or a sudden blurring of vision then this should always be checked as soon as possible preferably at an eye hospital.

If you have been checked for retinal detachment in the past you should have been given clear instructions on what to do if you have further symptoms and you should follow these. This usually involves contacting the hospital eye clinic if you have any concerns