Retinal Disorders - RETINAL TEARS AND DETACHMENT
What is the Retina?
The retina is the nerve layer at the back of the eye that senses light and sends images to your brain.
The eye is like a camera. The lens in the front of the eye focuses light into the retina. You can think of the retina as the film that lines the back of a camera. The centre of the camera film is called the macula. The vitreous is a gel that fills the inside of the eye.
What is a retinal detachment?
A retinal detachment occurs when the retina is pulled away from its normal position. The retina does not work when it is detached because the nutrition does not reach the retina. Therefore the vision is blurred in the area of the retina detachment. A retinal detachment is a serious condition and causes blindness unless it is treated.
What causes retinal detachment?
The vitreous is a clear gel that fills the middle of the eye. As we get older, the vitreous may pull away from its attachment at the back of the eye. This is termed VITREOUS DETACHMENT. Usually a vitreous detachment does not cause significant problems.
Sometimes the vitreous may have strong attachment to the retina. Sometimes the vitreous pulls hard enough to tear the retina in one or more places. The fluid inside the eye then passes through the retinal tear and lifts the retina off the back of the eye. This is like wall paper peeling
off a wall.
A retinal tear and detachment may also result in bleeding into the interior of the eye termed a VIRTEOUS HAEMORRHAGE.
The following conditions may increase the chance that you might get a retinal detachment.
Near sightedness (Myopia).
Previous retinal detachment in the other eye.
Family history of retinal detachment.
Previous injury to the eye .
Weak areas that have been identified by your ophthalmologist (lattice degeneration).
What are the warning symptoms of retinal detachment?
These are the early signs that may indicate the presence of a retinal detachment.
- Flashing lights. These are bright and very rapid flashes lasting seconds.
- Changes to the existing floaters or new floaters,
- A black curtain moving across your field of vision.
How to diagnose a retinal detachment?
An ophthalmologist can diagnose retinal detachment during an eye examination after dilating the pupils of your eyes. Only after careful examination can your ophthalmologist tell whether a retinal tear or early retinal detachment is present.
What treatment is needed?
In uncomplicated vitreous detachments no treatment is required. However your Ophthalmologist will arrange follow-up to ensure that no further problems occur.
Retinal tears require treatment using laser surgery or retinal cryotherapy (freezing), which seals the retina to the back of the eye.
Laser is often performed using a lens placed on the eye as an outpatient procedure in the clinic. Retinal cryotherapy is performed in the day surgery using local anesthesia. These procedures do not involve open surgery and are associated with little or no discomfort.
Patients with retinal detachment require more major surgery to put the retina back in its proper position.
There are several ways to fix a retinal detachment. The decision of which type of surgery depends on the characteristics of your detachment. In each of the following methods, the Ophthalmologist will locate the retinal tears and use laser surgery or cryotherapy to seal the tear.
A silicone band (scleral buckle) is placed around the outside of the eye to counteract the force pulling the retina out of place. The Ophthalmologist drains the fluid under the detached retina from the eye, pulling the retina to its normal position against the back of the wall of the eye. A gas bubble is injected into the vitreous space inside the eye. The gas pushes the retinal tear close against the back wall of the eye. Your ophthalmologist will ask you to maintain a certain head position for several days in order to place pressure on the area of retinal detachment. The gas bubble will gradually disappear over days to weeks depending on the type of gas used.
The vitreous gel, which is pulling on the retina is removed from the eye and usually replaced with a gas bubble. In cases of advanced retinal detachment, long term pressure on the retina is required silicone oil or heavy liquid is required. Your body’s own fluids will gradually replace the gas bubble. Sometimes vitrectomy is combined with a sclera buckle.
What to expect after surgery?
You can expect some discomfort after surgery. Your ophthalmologist will prescribe eye drops for you and advise you when to resume normal activity. If a gas bubble was placed in your eye, you may be required to keep the head in special positions. This may continue for several days. Do not fly in an airplane or travel to high altitudes until you are told the gas bubble is gone. A rapid increase in altitude may cause a dangerous rise in eye pressure. You will be given a wrist bracelet to warn medical staff against giving nitrous oxide whilst gas remains in the eye. If gas is used during surgery, vision will be poor until the gas bubble is absorbed by your body.
What are the risks of Surgery?
Any surgery has risks. However an untreated retinal detachment usually results in permanent severe vision loss or blindness. Some risks of surgery include:
- High eye pressure
Most retinal detachment surgery is successful, however a second operation is sometimes required. This may be due to scarring of the retina called proliferative vitreoretinopathy (PVR). This scar may pull on the retina causing it to tear and re-detach. If the retina cannot be reattached, the eye will continue to lose sight and ultimately becomes blind.
Will your vision improve?
Vision may take many months to improve and in some cases may never return fully. The more severe the detachment, the less vision returns. Therefore it is very important to see your ophthalmologist at the first sign of any trouble.
FLASHES AND FLOATERS
What are flashes?
Flashes are experienced as quick flashes of light which you see in your field of vision and may occur intermittently over days, weeks or months.
What causes flashes?
Filling the inside of your is a gel-like fluid called the vitreous. The vitreous is attached to the nerve layer which lines the back of your eye, called the retina.
Flashes are a symptom of your retina being irritated or stimulated by something.
As we grow older the vitreous gel changes in consistency and may separate from the retina. As the vitreous comes away from the retina it may pull at this delicate layer and cause flashes of light. This process is normal and only causes a problem if the vitreous is so firmly attached that the pulling creates a tear in the retina. The separation of the vitreous from the retina is called a posterior vitreous detachment. As well as being part of the ageing processes flashes may also occur in people who:
- Have experienced trauma to the head/eye
- Are near sighted (myopic)
- Have undergone laser or surgical procedures on the eye
- Have had inflammation inside the eye
Flashes may also be caused by migraine. These flashes normally appear in both eyes, may last for up to 20 minutes at a time and often look like jagged lines or “heat waves”. A migraine is caused by a spasm of blood vessels in the brain. If a headache follows the flashes we call this a migraine headache. If the flashes occur without the presence of a headache we call this ocular migraine. These flashes are not caused by the vitreous pulling at the retina.
Are flashes ever serious?
Flashes themselves are not serious but may be a warning sign that something serious is occurring inside your eye. If you notice a sudden onset of flashes you should see your Ophthalmologist as soon as possible for an examination of the retina.
How are flashes treated?
Flashes themselves cannot be treated. They are normally a symptom of detachment of the vitreous. If the vitreous tears the retina while it is detaching this can cause serious problems such as bleeding and detachment of the retina itself. These are serious complications and must be treated by an ophthalmologist as soon as possible.
What are floaters?
Floaters are tiny clumps of gel or cells inside the vitreous (the clear jelly-like fluid that fills the inside of your eye). You may see those as small specks or clouds moving in your field of vision. Often they are more obvious if you are looking at a plain background, like a blank wall or clear blue sky.
Even though the floaters look like they are in front of your eye, they are actually floating inside. What you see are the shadows they cast on the retina.
Floaters can have different shapes such as little dots, circles, lines, clouds or cobwebs.
What causes floaters?
When people reach middle age the vitreous gel may start to thicken or shrink, forming clumps or strands inside the eye and may pull away from the retina (posterior vitreous detachment). This is a common cause of floaters.
Are floaters ever serious?
Most people by the time they reach middle age will have floaters. Floaters themselves are not a serious problem but may be a warning sign that there is a serious problem occurring inside the eye. The detachment of the vitreous from the retina can cause tears and complications such as bleeding or retinal detachment. Retinal tears, bleeding and retinal detachment are very serious problems and must be examined by an Ophthalmologist. Urgent treatment such as laser or surgery may be required.
It is extremely important that if you notice sudden onset of floaters, an increase in existing floaters, or a shadow developing in your peripheral vision you should contact your Ophthalmologist right away.
How are floaters treated?
If the floaters are due to the changing consistency of the vitreous as part of the ageing process no treatment is required. Sometimes the floaters may interfere with work or activities of daily living and may be surgically removed.
If the floaters are a symptom of a more serious problem your Ophthalmologist will discuss treatment options with you.
Age-related macular degeneration, often called AMD or ARMD is the degeneration of the macula, which is the part of the retina responsible for the sharp, central vision needed to read or drive. Because the macula is affected in AMD, central vision loss may occur.
Macular degeneration is diagnosed as either dry or wet.
Dry Macular Degeneration (non-neovascular) is an early stage of the disease and may result from the aging and thinning of macular tissues, depositing of pigment in the macula or a combination of the two processes.
Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate in and around the macula. Gradual central vision loss may occur with dry macular degeneration but usually is not nearly as severe as wet AMD symptoms.
Wet Macular Degeneration (neovascular). Dry AMD may progresses to the more advanced and damaging form of the eye disease. The wet form of ARMD is where new blood vessels grow beneath the retina and leak blood and fluid. This leakage causes permanent damage to light-sensitive retinal cells, which die off and create blind spots in central vision.
Both dry and wet AMD cause no pain.
For dry AMD: the most common early sign is blurred vision. As fewer cells in the macula are able to function, people will see details less clearly in front of them, such as faces or words in a book. Often this blurred vision will go away in brighter light. If the loss of these light-sensing cells becomes great, people may see a small--but growing--blind spot in the middle of their field of vision.
\For wet AMD: the classic early symptom is that straight lines appear crooked. This results when fluid from the leaking blood vessels gathers and lifts the macula, distorting vision. A small blind spot may also appear in wet AMD, resulting in loss of one's central vision.
Slowing dry AMD's progression from the intermediate stage to the advanced stage will save vision from progressively worsening. The management involves taking specific high-dose formulation of antioxidants and zinc significantly to reduce the risk of advanced AMD and its associated vision loss.
Wet AMD can be treated with laser surgery, photodynamic therapy, and injections (ie.Lucentis) into the eye. None of these treatments is a cure for wet AMD. The disease and loss of vision may progress despite treatment.
although there are no drugs to restore vision lost to macular degeneration, there are some available that help prevent vision form getting worse or even improve the remaining vision. One of the latest advancements in treatment of macular degeneration is Lucentis. This drug targets the VEGF(vascular endothelial growth factor) protein, which is responsible for later stages of MD(“wet”) by promoting growth of abnormal vessels in the retina. Lucentis blocks this VEGF, which results in the reduction of abnormal vessels in the retina. Lucnetis blocks VEGF, which results in the reduction of leaking and swelling in the retina.
Lucentis is administered through an injection into the eye. It is a day procedure, which is done under a local anesthetic. After the injection, an antibiotic drop is used in the eye for a week to prevent any infections.
avastin is a monoclonal antibody that was developed for use in the treatment of certain cancers.
Like Lucnetis, it blocks the transmitter called VEGF, which is involved in growth and development of blood vessels.
In the eye, Avastin has been found to be useful in treating certain conditions where VEGF is thought to be involved. These conditions often involve leaking or bleeding blood vessels. Examples of such conditions include age-related macular degeneration, diabetic retinopathy, occluded retinal blood vessels, macular oedema. By blocking the action of VEGF, leakage and swelling in the retina can be reduced and even shut down.
Avastin is also given via an injection into the eye. It is a dry procedure, which is done under a local anesthetic. After the injection, an antibiotic drop is used in the eye for a week to prevent any infections.
Triamcinolone is a steroid, which is usually given via an injection into the eye. It is done under local anesthetic, and as a day procedure. After the injection, an antibiotic drop is used in the eye for a week.
Triamcinolone injections are used to treat macular oedema (swelling of the macula). The cause of the macular oedema may be related to macular degeneration, diabetic eye disease or post operative inflammation. The steroid acts to reduce the amount of accumulated fluid that thus settles the inflammation.
Immediately after the injection you will most likely notice a “black blob” in your vision. This is the triamcinolone suspended in the vitreous gel of the eye. Within two weeks the steroid will break up, and you may notice smaller “blobs” floating through your vision.
The main risks of injections into your eye include bleeding, infection and retinal detachment. Overall the risks of a severe adverse event are low, and probably less than 1 in 1000. Some patients experience a rise in eye pressure following the triamcinolone injection. This can usually be treated with drops or medications to lower the pressure.
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