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What are floaters?
Floaters are shapes or shadows that you can see drifting across your vision in a matter of seconds. The floaters may appear as small dots or irregularly shaped strands. The hollow space in the middle of your eyeball is filled by a clear, jelly-like substance called the vitreous gel. Anything that fills that cavity that is not transparent will cause the sensation of floaters. You usually notice floaters when looking at something plain, like a blank wall or a blue sky. Floaters are generally harmless and can become less noticeable over time, however, in some cases, they can be an indication of serious eye conditions, especially when they are associated with flashes of light or a dark curtain.
Causes of floaters associated with retinal detachment
Posterior vitreous detachment (PVD)
The retina is a thin layer of nerve tissue that lines the back of the eye and gives you the ability to see, very much like the film of a camera. With ageing, the gel on the inside of your eye shrinks and pulls off the retina. This is very common and occurs in 75% of people over the age of 65. It is the process of the gel pulling on the retina that stimulates the retina, causing your brain to interpret it as a light flashing in your eye. With time the gel will totally release from the retina and the flashing should stop. In approximately half of all people, the vitreous gel has separated from the retina by the time they are 60. This doesn’t usually cause any problems, and most people aren’t even aware that it has happened.
Retinal tears
If the gel pulls too hard on the retina without releasing, it can pull a tear in the retina. If you have a tear in your retina, it can lead to the release of many cells that float around in the vitreous gel causing the sensation of a sudden and dramatic increase in floaters. 50% of patients with symptomatic horseshoe tears develop retinal detachments.
Retinal detachment
Once you have a retinal tear, the fluid from the inside of the eye can pass through the tear and cause a separation between the retina and the layer supporting it on the back of your eye. This is called a retinal detachment. In the area where the retina is detached, your vision will be poor, and it appears as a constant and progressive dark curtain in your vision. If the retinal detachment progresses to the central area of the retina used for fine visual tasks like reading, recognising faces and driving, it could lead to a dramatic and permanent loss of vision.
There are many other causes of floaters, including:
- Vitreous syneresis (Ageing of the gel of the eye)
- Vascular disorders
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- Diabetic related eye disease (Please see section on diabetic related eye disease for more information)
- Retinal vascular occlusion or aneurysms
- Age related macular degeneration/ Polypoidal choroidal vasculopathy
- Inflammatory disorders
When should you see a doctor urgently?
If you have a sudden and dramatic increase in flashes, floaters, or you see a dark curtain in your vision that does not go away, you should see an eye care specialist urgently. Patients at particular risk for retinal tears or retinal detachment are patients that have had surgery to their eyes, are very nearsighted or have had a retinal detachment in their other eye or a close family relative. How are floaters treated?
If you find that your floaters significantly affect your vision or quality of life, they can be removed. Surgery may be performed to remove floaters under local anaesthesia with sedation or general anaesthesia. A pars plana vitrectomy is performed where the gel as well as the floaters in the inside of the eye are removed and replaced with clear fluid.
How is posterior vitreous detachment treated?
Posterior vitreous detachment generally only requires observation unless it is associated with a dramatic increase in flashes, floaters or a dark curtain. If you experience any of these symptoms, you need to see an eye care specialist urgently.
How are retinal tears treated?
Almost all patients with retinal tears require laser treatment to avoid a sight-threatening retinal detachment. Laser surgery may be performed with local anaesthesia in the clinic or with local anaesthesia and sedation in theatre. During laser application, you will see green flashes of light and experience minimal discomfort. Directly after laser treatment, your eye will be patched and still feel numb from the local anaesthesia. Some patients experience a mild headache after surgery that is easily taken away with paracetamol. By the next day, you will be able to function with your vision as it was before the laser was applied. This treatment forms an adhesion between the retina and the layer underneath it (kind of like "Spot welding" the retina to the layer underneath). Once an adhesion is formed, the fluid can't spread to other areas underneath the retina and lead to a retinal detachment.
How are retinal detachments treated?
Retinal detachment needs to be treated with surgery. Please see our segment on retinal detachment to find out more about treatment.
“Vision is the true creative rhythm”
- Robert Delaunay