RETINA

Retinal Detachment
Retinal detachment occurs when the thin lining at the back of your eye called the retina begins to pull away from the blood vessels that supply it with oxygen and nutrients.

Without prompt treatment, it will lead to blindness in the affected eye.

Symptoms
Initial symptoms of retinal detachment include the sudden appearance of floaters – black dots, specks or streaks that float across your field of vision.

Some people experience a kind of cobweb effect of lots of little floaters, while others report a single large black floater that looks like a housefly.

Usually only one eye is affected by floaters. Another common symptom is seeing flashes of light in the affected eye. These last no more than a second.

Without treatment, you will go on to experience increasing loss of vision in the affected eye. Most people report a shadow or “black curtain” spreading across their vision.

Causes
The most common cause of retinal detachment is when tiny holes develop inside the retina.
The holes then allow the fluid that is normally only found in between the retina and the lens of the eye to leak through underneath the retina.

If too much fluid builds up underneath the retina it can cause the retina to start pulling away from the blood vessels that supply the retina with blood. Without a constant blood supply, the nerve cells inside the retina will begin to die.

It is thought that the main reason these holes develop in the retina is that it becomes narrower and weakened with age.

People who are very short-sighted have the greatest risk of developing age-related retinal detachment (though in relative terms the risk is still very small) because they are often born with a retina that is thinner than normal in the first place. Previous eye surgery, such as a cataract removal, may also make the retina more vulnerable to damage.

In some cases, holes can develop if the eye experiences a sudden injury such as a punch to the face or a person being accidentally hit in the eye with a flying object.

Less common causes
Described below are less common causes of retinal detachment.

The fluid in front of the eye becomes unusually thick and it begins to pull the retina away from the blood vessels. This can sometimes occur as a complication of poorly controlled diabetes , the inherited blood disorder sickle cell anaemia and in babies who are born prematurely.
The retina remains unbroken but fluid from other sources gathers behind the retina. This can sometimes occur in conditions that cause inflammation and swelling inside the eye such as uveitis (which is where the middle layer of the eye becomes inflamed) and some rare types of cancer that develop inside the eye.

Diagnosis
The ophthalmologist can use a device called an ophthalmoscope, which is like a magnifying glass connected to a bright light source. This is used to study the back of your eye, check for any holes in your retina and see if the retina is out of position.

An ultrasound scan can also be used to obtain an image of your retina as well as the fluid in front of a retina. An ultrasound scan is a painless test where sound waves are used to build up an image of the inside of your eye.

Treatment
If retinal detachment has occurred, the only way of re-attaching the retina is with surgery.

Without surgery, total loss of vision is almost certain. In 90% of cases, only one operation is needed to re-attach the retina.

Surgery
Surgery for retinal detachment may be done under a general anaesthetic (where you are put to sleep) or a local anaesthetic (where drops are used to numb your eye and surrounding tissue).

You will be asked not to eat or drink anything for six hours before the operation. Afterwards, you may need to stay in hospital for one or two days, or you may be able to leave on the same day, depending on the circumstances.

Before you are given the anaesthetic, you will be given eye drops to widen your pupil. The retina is usually re-attached in a procedure using either scleral buckling or vitrectomy. These are explained below.

Scleral Buckling
Scleral buckling is the preferred way of re-attaching the retina if it has a tear or hole in it. Fine bands of silicone rubber or sponge are stitched onto the outside white of the eye (the sclera) in the area where the retina has detached. The bands act like a buckle and press the sclera in towards the middle of the eye, so the torn retina can lie against the wall of the eye.

Laser or freezing treatment is used to scar the tissue around the retina (see the box, right), which creates a seal between the retina and the wall of the eye and closes up the tear or hole.

The bands can be left on the eye and should not be noticeable after the operation.

Vitrectomy
Vitrectomy works by removing the fluid from the inside of the eye and replacing it with either a gas or silicone bubble. This holds the retina in position from the inside.

A vitrectomy may be recommended if the fluid in front of the eye is unusually thick and dense and is pulling the retina away from the underlying blood vessels.

Tiny dissolving stitches are used to close the wound. It is also possible to perform such surgery without the use of stitches, using smaller instruments. While this may lead to less discomfort, it is not known whether it is more effective.

After the procedure, you will be asked to keep your head in a certain position for a while, known as “posturing”, so the bubble lies against the retina.

If you have had a gas bubble put in your eye, you will not be able to travel by air for a while. Your doctor will tell you when it is safe to fly again. If you need another operation requiring general anaesthetic, you must tell your doctors about the gas bubble in your eye.

Complications
There is a small chance of developing complications during or after surgery, including:

bleeding inside the eye
more holes in the retina
bruising around the eye
high pressure or swelling inside the eye (glaucoma)
the lens of the eye becomes cloudy (cataract)
double vision
allergy to the medicine used
infection in the eye (this is very rare)
These complications are not common and can usually be treated. Sometimes you may need more than one operation to fix the retina.

Recovery
After the operation, your eyelids may feel itchy and sticky and some fluid may leak from your eye. There may be some bruising around the eye. These symptoms are perfectly normal and any discomfort should go away after a couple of days. You can take a simple painkiller such as paracetamol to relieve the discomfort.

A day after the operation, your doctor will give you some eye drops to reduce the swelling and prevent infection. It is important not to rub the eye while it heals, which will usually take two to six weeks.

If you have had a gas bubble in your eye, your vision will be very blurry for a while. This is only temporary.

It can take many months for vision to improve after surgery and in some cases you may experience some degree of permanent vision loss (but not complete blindness).

The amount of vision that can be successfully restored depends, for the most part, on how much of the retina was detached and for how long.

Prevention
There’s no way to prevent retinal detachment. However, being aware of the warning signs of a detached retina – floaters, bright flashes of light, or a shadow or curtain that seems to fall across your visual field – could help save your vision. If you notice any of the warning signs of retinal detachment, particularly if you’re over age 40, you or a family member has had a detached retina, or you’re extremely nearsighted, contact your ophthalmologist immediately.