1. Examination under anaesthetic (EUA)
Most babies and children initially have to be examined under anaesthetic. If their eye pressure is found to be raised, then surgery will usually be carried out at the same time to save a further anaesthetic. Every time a child is examined under anaesthetic, there is a chance that a further procedure may be required and parents should be aware of this. Generally speaking, a child can be examined without anaesthetic after the age of 5 years, but this can vary.
This is often the first operation to be performed. An incision is made into the filter system to open up the filter system that did not open properly as the eye developed. To get a good view sometimes the surface skin of the cornea needs to be removed. This regrows rapidly and heals within a day or two. However, during this period, the eyes will be uncomfortable and the child may not sleep well because of the discomfort.
Painkilling syrup (paracetamol, Calpol) may be prescribed. If a goniotomy is performed, both eyes will sometimes be operated on at the same time. In the majority of cases this operation lowers the IOP, but a second goniotomy may be required if the lowering of pressure is not sufficient. Another operation to create a new drainage channel (trabeculectomy) may be required if the eye does not respond to a reopening of the filter system.
In this operation, a very fine probe is threaded into the main collector channel (Schlemm's canal). This delicate probe is pushed through into the front chamber of the eye, creating a new drainage channel. This operation is used in certain types of glaucoma or when the cornea is not clear enough to perform a goniotomy. It can be combined with a trabeculectomy, where another new drainage channel is made in the eye.
This is when an entirely new drainage channel is made in the eye. A small flap is created by the surgeon, usually in the part of the eye just underneath the upper lid. This flap is secured with extremely fine stitches and is covered with the white skin of the eye (conjuctiva). The fluid accumulated underneath the skin of the eye then flows out of the eye and gets absorbed into the blood vessels surrounding the eyeball.
Following the operation, a tiny bump (known as a bleb) can sometimes be seen under the upper lid. This is a small collection of fluid draining away under the skin of the eye.
In some children a special drainage tube has to be inserted into the eye, to drain fluid out to a reservoir at the back of the eyeball. The reason for using this tube is that, in certain circumstances, it works better than the flap valve that is created during a trabeculectomy, and it will stay in the eye for an indefinite time. Anti-scarring treatment is used and a small stitch is sometimes left in the eye to control the amount of flow going through the tube. This stitch can easily be removed if the eye pressure rises in the future. Sometimes, one or two weeks after surgery, it may be necessary to put gas or jelly into the eye to adjust the pressure if it has become too low.
The child will not 'outgrow' the tube and some people have had them implanted for over 25 years.
Occasionally a small amount of scar tissue forms around the operation site after a trabeculectomy, or even after a drainage tube is implanted. This can sometimes be released by loosening some of the scar tissue with a very fine small needle (this procedure is called needling). After this procedure is carried out, anti-scarring treatment can be given, and sometimes a jelly-like substance is used to increase the effect of the anti-scarring injection. This jelly may occasionally be visible as a transparent lump in the eye which disappears after a few days.
Sometimes laser treatment is recommended. In this special form of laser treatment, an invisible laser is shone through the white coat of the eye onto the ciliary body (the tissue which produces the aqueous humour within the eye). This produces very small burns in the ciliary body and reduces the amount of aqueous humour the eye makes, resulting in a fall in the pressure of the eye. This is a relatively gentle treatment, but it often needs to be repeated several times. Sometimes the eye is a little red and inflamed after the procedure and steroid drops are required. Very occasionally, tablets which act like aspirin may be needed to reduce the inflammation after the laser treatment. It is usually necessary to continue treatment with eye drops and repeated laser treatments may be required.
If one eye is found to be lazy after examination, then patching treatment may be required.
This involves putting a patch on the good eye to force the weaker eye to work harder. A lazy eye occurs because the brain prefers to receive the signal from the better eye and switches off the connections to the weaker eye. If this is allowed to happen, normal connections between the weaker eye and the brain do not form and the vision in the eye is reduced, even though the eyeball itself may be in perfectly good condition. The patching treatment forces the brain to develop connections to the weaker eye. It is extremely important to persist with this patching treatment, as once the pressure is controlled, a good balance between the eyes may be the single most important factor in determining whether the eye sees well or not.