Sitting at the back of our eyes, the retina is the thin layer of nerves that enables our brains to receive light and transform it into images.
We can think of it as wallpaper lining the inner surface of the globe. Sometimes, however, the retina separates from the eye wall, causing visual loss perceived as a dark shadow spreading centrally from around the edge of our vision. Prior to this it is common to see floaters and flashing lights. We call this a retinal detachment – and while the condition is most common in people over the age of 40, it can happen to anyone at any time. Retinal detachments need to be treated quickly in order to prevent your vision from getting worse. Fortunately, they usually respond very well to surgery: the operation prevents further deterioration and should enable you to achieve a good level of vision afterwards, although this depends on whether or not the central vision has been damaged.
Retinal detachment is what happens when the light-sensitive retina – the nerve layer responsible for receiving light from the lens and converting it into signals for the brain – separates from the wall of the eye. This usually starts towards the periphery of the retina and spreads to the centre. Separation prevents the retina from functioning normally, leading to a worsening loss of vision. If the damage is not repaired promptly, it will result in permanent visual impairment, or even blindness in the affected eye.
It is common for the vitreous gel – the clear, jelly-like substance within the eye – to separate from the retina. This is known as posterior vitreous detachment, or PVD. This condition doesn’t cause permanent loss of vision, though you may find that floaters and misty vision become troublesome. However, since the vitreous gel is attached to the retina more firmly in some places than in others, the retina can tear as the gel separates.
Where does the retina sit within the eye? Learn more about the biology of your eyes.
Anyone can develop a retinal detachment at any time; it is unlikely that you have done anything to cause it. Some people, though, are at greater risk of developing this condition than others.
Some of the risk factors include:
- Age: As we grow older, our chances of developing posterior vitreous detachment (PVD) increase; this in turn brings a greater risk of retinal detachment.
- Myopia (short-sightedness): Short-sighted people are much more susceptible because their eyes are larger than average. This results in a thinner and more fragile retina. People with myopia also tend to develop PVD earlier, and are more prone to weakness of peripheral retina.
- Trauma: A direct impact to the face or eye can cause a detachment.
- Cataract surgery: Any form of intraocular surgery slightly increases the risk of detachment.
- Familial retinal detachment: When you inherit a retinal weakness in your genes – though this is rare.
If you have a retinal detachment in one eye, you are at greater risk of developing a similar change in the other.
We will examine your other eye to see if it might need preventative laser treatment.
What is Posterior Vitreous Detachment (PVD)? Find out more about this common eye condition.
Common symptoms of posterior vitreous detachment (PVD) are:
- flashes of light seen as arcs in the periphery of vision. These will be more noticeable in dim conditions.
- new floaters, which may vary from small spots or “cobwebs”, to larger patches of mistiness that flick across the field of vision when you move your eye.
Common symptoms of retinal detachment are:
- a shadow that spreads across the vision, starting on the peripheries and then moving to the centre.
- central vision that is blurred or distorted; this implies that the central macular retina is involved.
! Action Point: If you are experiencing these or any other symptoms of retinal detachment or PVD, you should report them as a matter of urgency to your optometrist or local eye casualty.
Comparison of a healthy eye and an eye with retinal detachment.
There are a number of different ways to treat retinal detachment. The most appropriate treatment for you will depend on the type, location and extent of your detachment. In repair surgery, the goal is to reposition the retina onto the inside wall of the eye. In 90% of cases this can be achieved with a single operation. The reason for proceeding with surgery is to prevent blindness.
Many retinal detachments constitute a medical emergency. There is a limited window of opportunity to repair the detachment before permanent visual loss occurs. The aim of surgery is to intervene before the detachment progresses to the central macula, which you would perceive as a cloud or curtain coming across the centre of your vision.
While your peripheral vision will improve following a detachment repair, central vision never fully recovers if it has been affected. If the loss of central vision is recent, however, urgent surgery to reattach the macular retina can achieve a substantial improvement in central vision.
Occasionally, a longstanding detachment with limited progress will leaves the central vision unaffected. In these cases, surgery is not urgent.