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What is the macula?
The back of the eye is lined with a thin layer of tissue called the retina. The retina is like the film in a camera. It is the "seeing" tissue of the eye. When light hits the retina, a picture is taken. This picture is then sent to the brain through the optic nerve. This is how we see.
The retina has two parts; the peripheral retina and the macula. The macula is used to see very fine detail straight ahead, to read small print, and to recognise faces. The peripheral retina gives you your side vision.
A macular hole is an abnormal opening that forms in the centre of the macula. It usually develops over a period of several weeks to months.
In the very early stages of a macular hole forming, the vision can become blurred and distorted. If the hole progresses, a blind spot develops in the centre of vision. When this happens, central or detailed vision is lost. A blind spot develops directly in the centre of what you are looking at.
The peripheral vision remains normal. There is no pain associated with a macular hole forming.
Our eye is filled with an egg-white like substance called the vitreous. As a person ages, the vitreous becomes less like a gel and more like a fluid. Due to this movement of fluid, the vitreous begins to pull on the retina and separates itself from the retina. This is a normal process that eventually occurs in all people and very infrequently causes a problem.
In some people, however, the vitreous is attached very firmly to the centre of the eye, the macula. When the vitreous starts to contract and separate, it can sometimes pull a very tiny tear at the macula. The torn area gradually enlarges to form a round hole.
There are other causes of a macular hole, including injury or trauma, as well as long term swelling of the macula.
Your ophthalmologist can diagnose a macular hole by looking inside your eye with a special instrument called an “ophthalmoscope”. They will also ask you to look at a thin beam of light to determine whether the hole is fully formed or not.
You will require photographs to be taken of your eye to confirm the diagnosis. A special photographic study called a fluorescein angiogram may be performed to determine the extent of damage to the macula, as well as checking that there are no other problems with your retina. Optical Coherence Tomography (OCT) may also be performed, allowing us to examine a cross section of your retina.
Once a macular hole develops, vitrectomy surgery is the only treatment available that can repair a hole, and possibly improve the vision.
Vitrectomy surgery is performed under local anaesthesia. You will be given a small amount of sedation whilst your eye is put to sleep. This takes about five minutes. The eye surgeon will talk to you during your operation. The operation usually takes 45 minutes.
Using 23 gauge microsurgical instruments, the vitreous gel is removed from the centre of the eye. During the course of the surgery a fluid- which is similar to the fluid naturally produced by cells inside of the eye- is used to replace the vitreous.
This surgery is sutureless. The benefits of sutureless surgery include minimal conjunctival scarring, faster visual recovery, decreased discomfort in the eye, and overall increased patient satisfaction.
A special gas bubble is injected into the eye to help the hole heal and hold the retina in place. This gas bubble will slowly dissolve over a period of three to eight weeks.
Following surgery, the patient must posture in a special “face down” position for five days. This is so the gas bubble is kept in contact with the macula and can exert pressure on it. There are special beds or pillows available to help you maintain this face down position. You may have four breaks of half an hour spread out throughout the day where you do not have to keep your head in the "face down" position.
A successful visual result is very dependent upon a patient maintaining the correct face down positioning for the time required. If the macular hole closes, the eye will slowly regain part of the lost sight. The visual outcome may depend on how long the hole was present before surgery.
Surgery is not for everyone who has a macular hole. Some people who have normal vision in the other eye and are not affected by the macular hole may choose not to have the operation.
An untreated macular hole will never send you completely blind. Your central vision will deteriorate further as the macular hole enlarges, but your peripheral vision will remain intact. This means that it will become increasingly more difficult to recognise faces, read, and perform very fine work with the eye.
Like any surgery, there are always associated risks. The severe complications associated with this type of operation are very rare. These include infection, retinal detachment, haemorrhage, and loss of side vision.
The more common risks associated with surgery are the formation of a cataract, an increase in ocular pressure and small retinal tears. The complications that can arise from these more common risks can become severe if not treated. If a cataract forms this can be removed in time. If the ocular pressure increases this is usually short-term and can be treated with drops.
The most common risk is a retinal tear or break. These will usually be seen during the operation and the surgeon will often tell you that he is checking for any weak areas in your retina towards the end of the operation. These weak areas will be attended to immediately with a special freezing treatment called cryotherapy or with a laser. Left untreated, these breaks can sometimes lead to a retinal detachment.
It is very important that you do not fly in an aeroplane whilst a gas bubble is in your eye. It is also important that you let your ophthalmologist know if you will be travelling up to a higher altitude. A rapid increase in altitude can cause a dangerous rise in the pressure in your eyeball.
If you are having any other form of surgery and a gas bubble is still present in your eye, you must let the surgeon know as some forms of anaesthesia can affect the gas. You will be given a wrist bracelet to warn Medical Staff against giving nitrous oxide whilst gas remains in the eye.
Avoid any heavy lifting, swimming or very strenuous exercise for approximately three weeks following your operation.
You will notice the gas bubble slowly becoming smaller with time. This is normal. The vision should be clear above the gas bubble. Your doctor will tell you when it is time for you to change your glasses and will let you know when the gas has fully gone. If gas is used during surgery, vision will be poor until the gas bubble is absorbed by your body.
It is important to remember that a macular hole has a 10% chance of occurring in the other eye. There is nothing that you can do to prevent a macular hole from forming.
It is a good idea to have your eyes examined regularly by an ophthalmologist to detect any problems early.