Selective Laser Trabeculoplasty (SLT) is a procedure used to reduce the pressure in the eye (intraocular pressure also known as IOP) to prevent damage to the optic nerve and sight loss.
IOP is controlled by the production and drainage of fluid known as aqueous humour in the eye. When there is poor drainage, the IOP increases and can damage the optic nerve at the back of the eye (which transmits visual information to the brain). This leads to glaucoma which in turn causes sight loss.
How does SLT work?
During SLT, a laser beam is applied to the drainage angle which helps to unclog the trabecular meshwork. The aqueous humour can then drain more easily through the channels, bringing down the pressure.
SLT uses short pulses of relatively low-energy light to target only the cells with the pigment melanin in the drainage channel of the eye. This gentle laser treatment induces an immune response from the body. The immune cells clear debris in the meshwork so that it functions more effectively and that reduces the eye pressure.
Success
SLT lowers intraocular pressure by about 30% when used as initial therapy and the 2022 updated UK National Institute for Health and Clinical Excellence (NICE) guidelines approved SLT as a first line treatment for glaucoma.
If you are on drops already, the intraocular pressure reduction is less but it may be possible to reduce the number of eye drops taken to manage your glaucoma. When successful, the effect lasts between one to five years however, the procedure may need to be repeated in the future for adequate pressure control.
SLT cannot restore sight that is lost, but the aim is to preserve vision.
Advantages
Risks
Complications are generally mild and may include inflammation and sometimes an increase in eye pressure, which can feel sore. It is natural for the eye to be a little red and sore and the vision to be altered for about six hours post procedure.
In very rare cases clouding of the cornea, bleeding in the eye and swelling of the retina (cystoid macular oedema) may occur.
The procedure
You should NOT drive to the clinic on the day of your procedure and will need a responsible adult to take you home.
Before you have the laser treatment, the consultant will check your vision and complete your written consent form for you to sign. They will answer any questions you may have and explain the procedure.
The treatment takes 10 to 15 minutes per eye.
The consultant will put some drops put into the eye; one to control against pressure rise and one to numb the eye. You may also be given a drop to make the pupil smaller. If this is the case, the last drop may give you a headache and slightly blur your vision and we will give you paracetamol to ease any discomfort or pain. You will sit at a machine similar to the slit lamp used in an eye clinic, but this one has a laser attached.
The doctor will place a contact lens on your eye, so they can clearly see the drainage angle and apply the laser.
The consultant will check the pressure in your eye an hour later.
You can then be driven home and return to work and resume driving the next day as well as carrying on with your usual activities.
Recovery
After the procedure, your vision will be blurred for a few hours. Your eyes may also feel uncomfortable or ache and be a bit red for two to three days. You may be prescribed steroid or anti-inflammatory drops for five to seven days.
If you are already on glaucoma eye drops you should continue taking them unless instructed otherwise.
If you experience a mild headache, you can take oral painkillers for example Paracetamol.
You will be given a follow-up appointment for six to eight weeks later.
When to seek further medical advice
You should contact your GP or dial 111 out of hours if you experience:
