A retinal detachment occurs when the light-sensitive layer (retina) separates from the back of the eye. The retina is the part of the eye where a picture is focussed. Without the retina in place the eye is not able to send visual information to the brain and so its detachment leads to profound loss of sight.
The lifetime risk of retinal detachment is about 1 in 300, although it becomes much more common with increasing myopia and when there is a family history of the condition. For people with very high levels of myopia the lifetime risk is about 1 in 20.
Most retinal detachments originate from a break in the retina that allows fluid to pass through and lift the retina from the inside of the eye, much like a bubble under wallpaper.
The retinal break is often the result of traction from the vitreous gel as it peels away in a posterior vitreous detachment. The overwhelming majority of posterior vitreous detachments are not associated with any significant problems; those that do result in a retinal break are usually is eyes where there are pre-existing unusually firm vitreoretinal attachments or a particularly fragile retina. It is for these reasons that most retinal detachments occur in myopia, an optical defocus caused by an eyeball that is too long and associated with a relatively stretched retina with degenerative areas at its edge.
Trauma is another cause of breaks in the retina, and consequently retinal detachment.
Less commonly the retina becomes detached by a different mechanism to that described above. The contracture of fibrotic tissue at the back of the eye in advanced diabetic retinopathy can pull the retina and produce a tractional detachment.
Most retinal detachments starts at a retinal break at the edge of the retina, and this leads to a dark patch at the edge of vision that enlarges as the detachment extends. However, the onset of the condition is more commonly noticed by the symptoms of new floaters and flashes .
- Sudden increase in the number of floaters
- Flashes of light
- Dark shadow that starts at the edge of vision and extends centrally
- Impression of a veil or curtain over vision
It is not possible to confidently differentiate between a harmless posterior vitreous detachment and one associated with a retinal detachment on the basis on symptoms alone. This is why anyone who is experiencing new floaters or flashes should undergo a dilated eye examination.
Most people with a retinal detachment will need prompt surgery to avoid blindness. It is not always possible to restore vision completely, and this is more likely when the retina has been detached for a few days.
The first part of surgery is to reposition the retina. Afterwards, multiple small burns are applied using a laser or a cryoprobe is used to freeze that area around the retinal break. The scarring is achieved by small applying burn or acts to stick the retina down and so prevent the passage of fluid through the break and thus reoccurrence of the retinal detachment.
A gas bubble or silicone oil bubble is injected into the eye and floated to the area of detachment the retina back in place. A laser is then used seal the retinal break.in the eye. When the gas bubble is used, patients may have to keep their heads tilted for several days to keep it in contact with the retinal hole. This often makes the treatment impractical when the retinal tear occurs in the lower part of the eyeball.
Scleral buckle surgery
One or more silicone bands are tied to the outside of the eyeball. These bands push the wall of the eye against the retinal hole, closing the hole and allowing the retina to reattach. The bands do not usually have to be removed.