Bright Sight

Oliver Backhouse, Consultant Eye Surgeon www.cataract.org.uk

Cataracts and uveitis

The lens inside the human eye is transparent and, due to the ability of it to change shape, allows fine focusing to take place. When it turns cloudy, this is called a cataract. Cataract is extremely common in the elderly although it can occur at any age.

Uveitis is a name given to a large group of disorders causing inflammation inside the eye. This inflammation can cause a cataract to form that may produce blurred vision. When this becomes a problem an operation to remove the cataract can be considered. Laser can not remove a cataract.

CATARACT SURGERY

Removing a cataract is the most common operation performed by eye surgeons and happens thousands of times each year at this hospital. Modern techniques have made the operation extremely reliable.

Cataract operations can be performed under local (drops / injection to ‘numb’ the eye) or general anaesthetic (when the patient is put to sleep). Only a few patients need to be admitted to hospital to stay the night. The operation usually takes under 20 minutes. During the operation a small incision is made at the upper edge of the cornea, underneath the upper eyelid. The cataract is removed and a synthetic lens put in place of it. This helps the eye to focus after the operation and stays in the eye for life. This artificial lens can not change shape so glasses will be needed after the operation to achieve the change of focus at various distances (eg. distance to reading). The eyes are tested for glasses after a few weeks. Eye drops are required after the operation to help control any inflammation from the surgery.

CATARACT SURGERY IN PATIENTS WITH UVEITIS

If your cataract has arisen as a complication of uveitis, an operation to remove it is less straightforward. This will vary from patient to patient and the issues will be discussed with you in the clinic before any decision is made.

1. Inflammation:

Even a normal cataract operation produces inflammation inside the eye but in patients with uveitis there is more inflammation than usual. This may be minimal or severe.

Special precautions are taken to minimise the inflammation –

  • Wait for the eye to be free of inflammation before surgery is undertaken.
  • If this is not possible, reduce the inflammation with frequent drops / tablets for a few weeks before the operation.
  • At the time of surgery and afterwards, more treatment is given. Steroid treatment is then reduced over several weeks after the operation, with the aim of returning to pre-operation treatment within 3 months.

2. The Operation:

The operation can be technically more difficult due to the scarring inside the eye from the uveitis and so the operation can take longer. Due to this and the frequent young age of the patients, more general anesthesia is used. Sometimes it is preferable to stay in hospital overnight after surgery.

3. The Lens Implant:

The best way to get good vision following a cataract operation is to put a synthetic lens into the eye. Contact lenses or thick glasses are an alternative. Occasionally putting a synthetic lens into the eye causes the inflammation to be worse. The benefits and risks of putting a lens into the eye will be discussed with you before any decision is made. In most cases it is safe.

4. After the Operation:

Frequent outpatient attendance is required in the first few weeks after the operation to keep a close watch on the eye. Generally, you will be seen weekly for the first 4 weeks and then the intervals between visits will be increased. A combination of frequent drops will be prescribed and it is very important that you take them as directed. Glasses will be looked into after a few weeks.

5. Reading glasses:

It is normal, usually sometime after the age of 40, to need reading glasses as the lens inside the eye looses its ability to alter focal distance. The various types of synthetic lens used in cataract operations have a fixed distance of focus and so glasses will be needed to change the focus of the eye (eg from far to reading) following cataract surgery. As many people with cataract due to uveitis are under the age of 40, they will experience a need for glasses in order to acquire the best vision possible in their eye following cataract surgery.

6. Possible complications of a cataract operation:

No operation is entirely without risk. A cataract operation is perhaps one of the most reliable operations in medicine today, but very uncommonly, complications occur. Rarely, problems with the anesthetic (either local or general) can be dangerous to life. Very uncommonly an infection develops inside the eye after the operation. This, and other rare complications can make vision worse after the operation than it was before. However, the overwhelming majority of cataract operations are uneventful and successful.

In addition to the above complications which may rarely affect any patient undergoing a cataract operation, there are some which are more common in patients with uveitis. The problem of inflammation has already been mentioned. There are various other issues:

A) Expectation of improvement.

People with uveitis have poor vision, not only because of cataract, but also because of other problems inside the eye. Some of these problems may be permanent. Sometimes it is useful to remove a cataract, on the understanding that other problems may limit the improvement in vision. Occasionally it is not possible to predict whether the vision will improve much, if at all, when a cataract is removed. Each patient is different. It is always important, when deciding to remove a cataract in a patient with uveitis, to balance the likelihood of improvement against the risks of surgery.

B) Glaucoma.

Some patients with uveitis develop high pressure inside the eye, which over a period of time may cause damage to vision. This is called glaucoma. Sometimes glaucoma develops after a cataract operation or, if already present, may require more treatment. Glaucoma can usually be controlled using eye drops, but sometimes an operation is necessary.

C) Floaters.

Some patients with uveitis form opacities which float around inside the eye. These can be seen as ‘floaters’ in the vision when viewed against a bright background. Floaters are not removed by a cataract operation. On the contrary, after a cataract operation they sometimes become more visible again. If floaters are very dense and begin themselves to obscure vision, it is possible to perform an operation to remove them. This is a more major operation than a cataract operation, and is only performed when necessary.

D) The Retina.

The retina is the nerve cell layer at the back of the eye which forms images. It can be permanently damaged by uveitis. The most common way in which it can be damaged is by swelling caused by an accumulation of fluid. This will eventually lead to scarring, which will have a permanent effect on vision, and for which there is no treatment. This swelling is common in some forms of uveitis, and there are treatments which attempt to prevent it from causing permanent scarring. The condition may occur only as a result of a recent cataract operation, and is one of the important risks which may affect outcome.

Disclaimer: Adapted from Manchester uveitis patient leaflet.