Posterior Vitreous Detachment
The eye is like a camera with a lens at the front and a light sensitive film (the retina) at the back. Filling the space between these is a transparent jelly called the vitreous. As we get older the vitreous loses its volume and tends to pull away from the retina. As it comes away from the retina, it may cause flashes of light that lasts for less than a second. Small clumps form in the vitreous and these can be seen as ‘floaters’ in the vision (often mistaken for flies or cobwebs). This is called posterior vitreous detachment (PVD).
Usually a PVD does not cause any long term problems for vision. However rarely, the vitreous jelly may pull and tear the retina and if left untreated this can progress to a retinal detachment and cause blindness. It is thus very important not to ignore new symptoms of flashes, floaters or cobwebs in vision.
Most retinal tears are small and can be treated using laser or cryotherapy (freezing procedure). This seals the tear and reduces the risk of a retinal detachment.
This is a condition where the retina peels away from the wall of the eye. In most cases the retina detaches because a hole or a tear has formed in the retina allowing fluid to pass underneath the retina.
Treatment involves surgery whose main aim is to seal holes in the retina and reattach the retina. The two methods used in retinal detachment surgery are vitrectomy or scleral buckle or a combination of the two.
This procedure involves removing the vitreous gel (that has caused the retinal tear) from inside the eye. Then to seal the tear the surgeon uses either laser or a freezing probe to make a scar around the tear. A gas or silicone oil bubble is then inserted into the eye to support the retina while it heals. A gas bubble slowly absorbs over 2 to 8 weeks but a silicone oil bubble will need a small operation to remove it at a later date. Your vision will be very blurred initially due to the presence of the gas or oil bubble.
The retinal holes can also be sealed and supported by stitching a piece of silicone rubber or sponge to the outside of the eye. This acts as a ‘splint’ and produces a dent within the eye and pushes the outer wall of the eye up to the hole in the retina. The buckle is not visible on the outside of the eye and usually remains in place permanently.
Retinal detachment surgery can be performed under local anaesthetic or general anaesthetic. Under local anaesthetic you will be awake but you will not feel any discomfort as the eye will be numbed with an injection. You will not see the operation and the other eye will be covered. If a general anaesthetic is chosen then you will be fully asleep. The decision as to which type of anaesthesia is most suitable will be made following a discussion between you and your surgeon.
If you have been given any posturing instructions then these should be followed. You can bath or shower, but avoid splashing water near the eye. Generally you may do anything with which you are comfortable. Most people choose not to drive over the first few weeks. You must not fly until the gas bubble has gone and you must inform the anaesthetist if you require a general anaesthetic for any operation while there is gas in your eye.
Risks of Retinal Detachment Surgery
Retinal detachment surgery is not always successful. Every patient is different and some retinal detachments are harder to treat than others. Some patients may need more than one operation. These are the risks and benefits that will be explained to you before you give consent for surgery:
The success rate for retinal detachment surgery is approximately 90% with a single operation. This means that 1 in 10 people (10%) will need more than one operation. The reasons for this are new tears forming in the retina or the eye forming scar tissue which contracts and pulls off the retina again.
If a gas or oil bubble is used during surgery then you will usually develop a cataract in the eye within the first 18 months. A cataract is the lens of the eye becoming cloudy and will require a short operation to remove it.
Any surgical procedure carries a risk of haemorrhage and infection but in retinal detachment surgery this risk is very low (less than one in a thousand). Although it is rare, it does have serious consequences as it can cause blindness.