In the front compartment of the eye is a circulating fluid called aqueous humour. This fluid is constantly being produced and drained away to maintain a normal eye pressure (intraocular pressure).
Sometimes the drainage system can become unable to cope, causing the eye pressure to rise to a point where it can cause optic (eye) nerve damage. You may already be using eye drops to help reduce eye pressure to protect the optic nerve from further damage.
Sometimes eye drops are not enough to lower eye pressure alone and SLT treatment may be beneficial.