The vitreous is the jelly like material that fills the back of the eye. When we are born it is a solid gel, firmly attached to the retina. With age the adhesion between the vitreous and the retina loosens and the vitreous separates from the retina. This process is like peeling sticky tape from paper and usually the vitreous peels off the retina without problems. In some cases, the vitreous remains stuck at the macula, causing Vitreo-Macular Traction (VMT).
The macula is the most important part of the retina, which is like the film in a camera. The macula is the part of the retina that gives us sharp central vision for reading. In VMT the vitreous pulls on the macula and starts to stretch and split the retina. In some cases the pulling (traction) remains mild and does not significantly alter the vision. In other cases, the pulling continues to worsen and this may damage the macula and cause the vision to become distorted and blurred. If the pulling continues to progress, permanent damage to the central vision may occur.
What is the treatment for VMT?
If VMT is mild and not interfering with your vision, no treatment is required. An annual review and OCT scan to monitor for progression are important. In some cases the VMT can remain stable and in some cases it may resolve spontaneously. In other cases, the VMT progressively gets worse with more distortion and worse vision. Once the membrane begins to cause progressive damage to your vision, it should be fixed surgically, with a vitrectomy.
Fig 1. OCT view of a normal macula
Fig 2. OCT scan of Vitreomacular Traction
What is vitrectomy surgery like?
Modern surgery allows us to very successfully correct vitreomacular traction. This is performed using very fine microsurgical “keyhole” instruments to gently peel the vitreous from the retina. These tiny instruments are smaller than a blood test needle and usually no sutures are required. The surgery takes less than one hour, and is usually performed using local anesthetic with “twilight” sedation. An anaesthetist will provide relaxant medication and the eye is completely numb with anaesthetic so there is no pain. It is day surgery and you do not need to stay in hospital over night.
Occasionally we will need to use a gas or air bubble to help repair your eye. As long as you do not have a retinal detachment you will NOT need to position face down after surgery.
What is the chance of my vision improving?
In more than 90% of cases, once the membrane is removed, the distortion and the vision will improve. How much vision is restored depends on your general health, the health of your eye and the length of time that the traction has been present. In general, most people regain around 50 % of the vision they have lost, however some will gain more and some less. The earlier the VMT is diagnosed and treated, the better the final outcome. Your vision will continue to improve slowly for up to one year.
What happens after the surgery?
Following surgery, the vision will be mildly blurred for the first week due to mild swelling. For the first 24 hours it is best to rest at home. Computer work and watching television are fine.
A protective shield is recommended for sleeping, for the first week after the surgery and you will be required to have eye drops for one month. You can resume light activities a few days after surgery. Depending on your type of work, some people return to work within a few days, others may require a week or longer off for heavy physical activity. New glasses may be required a few months after surgery.
What are the risks of surgery?
Although Vitrectomy surgery is a very successful surgery, one should be aware that all surgery has risks, and occasionally problems can arise :
- A cataract may develop earlier than would be expected during the normal aging process.
- The eye may develop increased pressure (glaucoma) and medication may be required.
- Retinal tears or detachment of the retina may develop during surgery, or following surgery, and may require further surgery to correct these.
- Infection and haemorrhage are very rare risks which may occur with any surgery. If you notice pain or decreased vision following surgery, Dr Donaldson’s consulting rooms should be contacted on 3831 0101 as soon as possible. Infections often treatable if detected early. A severe infection or severe bleeding can result in permanent blindness, but this is very rare, much less than 0.1%.
- The chance of this being required is generally less than 1%. If you have a gas bubble it is very important not to sleep on your back, or lie on your back for extended periods, as in this position the gas bubble will rub on your lens
- While a bubble is present, you MUST NOT FLY in an airplane. This could result in blindness as the bubble expands with altitude.
- If you need to travel over the Toowoomba ranges please mention this to your doctor.
- If you require surgery of any other kind over the following two months you must tell the anesthetist about the gas bubble as nitrous gas anaesthetics will cause the bubble to expand and cause severe vision threatening pressure rises.