Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment, the entire retina may detach. This will lead to vision loss and blindness.
The retina is a thin layer of light-sensitive tissue on the back wall of the eye much like film in a camera. Its job is to translate what we see into neural impulses and send them to the brain via the optic nerve. Most retinal detachments occur spontaneously due to a tear in the retina, which can occur during vitreous separation. Occasionally, injury or trauma to the eye or head may cause a small tear in the retina. This will allow fluid to seep through and peel it away like a bubble in wallpaper.
Rhegmatogenous retinal detachment
An rhegmatogenous retinal detachment occurs due to a hole, tear, or break in the retinal that allows fluid to pass into the subretinal space between the sensory retina and the retinal pigment epithelium.
Exudative or secondary retinal detachment
An exudative retinal detachment occurs due to inflammation or injury that results in fluid accumulating underneath the retina without the presence of a hole, tear or break.
Tractional retinal detachment
A tractional retinal detachment occurs when fibrovascular tissue, that has developed on the surface of the retina caused by an injury, inflammation or diabetes pulls the sensory retina from the underlying layer of the tissue.
The risk of retinal detachment in otherwise normal eyes is around 5 per 100,000 per year. Detachment is more frequent in the middle-aged or elderly population, with rates of around 20 per 100,000 per year. The lifetime risk in normal eyes is about 1 in 300.
- Retinal detachment is more common in those with severe or extreme myopia (above 5-6 diopters) as their eyes are longer and the retina is stretched thin. The lifetime risk increases to 1 in 20. Myopia is associated with 67% of retinal detachment cases. Myopic patients are often younger than non-myopic ones with detachments.
- Retinal detachment can occur more frequently after surgery for cataracts. The estimate of risk of retinal detachment after cataract surgery is 5 to 16 per 1000 cataract operations. The risk may be much higher in those who are highly myopic, with a frequency of 7% reported in one study. Young age at cataract removal further increased risk in this study.
- Tractional retinal detachments can also occur in patients with proliferative diabetic retinopathy or those with proliferative retinopathy of sickle cell disease. In proliferative retinopathy, abnormal blood vessels (neovascularization) grow within the retina and extend into the vitreous. In advanced disease, the vessels can pull the retina away from the back wall of the eye, causing a traction retinal detachment.
Although retinal detachment usually occurs in one eye, there is a 15% chance of developing it in the other eye.
People who suffer from retinal detachment feel no pain. A retinal detachment is commonly preceded by a posterior vitreous detachment which gives rise to these symptoms:
- **Flashes of light (photopsia): Very brief in the extreme temporal (outside away from the nose) part of vision.
- A sudden dramatic increase in the number of **floaters.
- A ring of floaters or hairs just to the temporal side of the central vision.
- A slight feeling of heaviness in the eye.
Although most posterior **vitreous detachments do not progress to retinal detachments, those that do produce the following symptoms:
- A dense shadow that starts in the peripheral vision and slowly progresses towards the central vision.
- The impression that a veil or curtain was drawn over the field of vision.
- Straight lines (scale, edge of the wall, road, etc.) that suddenly appear curved (positive Amsler grid test).
- Central visual loss.
There are several methods of treating a detached retina, all of which depend on finding and closing the holes (tears) which have formed in the retina.
Scleral Buckle Surgery
Scleral buckle surgery is a common treatment in which the eye surgeon sews one or more silicone (bands or reinforcements) to the outside of the eyeball. The bands push the wall of the eye against the retinal hole, closing the hole and allowing the retina to re-attach. The bands do not usually have to be removed. The encircling band used in the repair of retinal detachments may elongate the eye and increase myopia.
This is another method of repairing a retinal detachment in which a gas or bubble is injected into the eye. The bubble floats to the area of the detachment where it must remain to apply light pressure against the hole and help push the retina back into position. The surface tension of the air/water interface seals the hole in the retina and allows the retinal pigment epithelium to pump the subretinal space dry. This enables the retina to be pulled back into place. 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.
** VITRECTOMY is a widely used treatment for retinal detachment in countries with modern healthcare systems. It involves the removal of the ** VITREOUS GEL using microsurgery combined with filling the eye with a gas bubble and laser.
Cryopexy and Laser Photocoagulation
Cryotherapy (freezing) and laser photocoagulation are treatments used to create a seal or scar around the retinal hole to prevent further fluid from accumulating behind the retina and to keep the retina from re-detaching. Cryopexy can be used to seal anterior retinal tears and photocoagulation to seal posterior breaks.
After treatment, patients gradually regain their vision, although the visual acuity may not be as good as it was prior to the detachment. This is the case particularly if the **MACULA was involved in the area of detachment. However, if left untreated, total blindness will result.
Retinal detachment can be prevented in some individuals. The most effective way of preventing retinal detachment is educating people to seek ophthalmic medical attention if they suffer symptoms suggestive of a posterior vitreous detachment. Early examination allows detection of retinal tears which can be treated with laser or cryotherapy. This reduces the risk of retinal detachment in those who have tears.
There are some known risk factors for retinal detachment.
Cataract surgery can increase the risk of retinal detachment even a long time after the operation. The risk is higher if there are complications during cataract surgery. In general, the risks of detachments have decreased with modern cataract surgery.
Trauma is a less frequent cause. Activities which cause direct trauma to the eye (boxing, kick-boxing, karate and others) can cause a particular type of retinal tear called a retinal dialysis. This type of tear can be detected and treated before it develops into a retinal detachment. For this reason, governing bodies in some of these sports require regular ophthalmic examination.
Individuals prone to retinal detachment due to a high level of myopia are encouraged to avoid activities where there is a risk of shock to the head or eyes.