Glaucoma can sometimes be treated successfully with medications to lower the pressure in the eye. If medications are not effective, laser and other surgical procedures could be of value in controlling the pressure and preventing further vision loss. Both medications and surgery are designed to do one of two things:
- Decrease the amount of fluid production in the eye from the cells that make the fluid
- Help the fluid flow out of the eye
Selective laser trabeculopasty (SLT) is one option for lowering intraocular pressure (IOP) for patients who have open-angle glaucoma in the early stages. It can also be used in combination with drug therapy or as an alternative therapy when drugs fail. It is a flexible treatment option and can be repeated if necessary, depending on the individual patient's response.
How it works
The trabecular meshwork is around the periphery of the iris and is where fluid formed in the eye drains out of the eye. This meshwork is treated directly with the laser to improve drainage through it.
SLT uses short pulses of relatively low- energy light to target only the melanin- rich cells in the drainage channel of the eye. The laser pulses affect only these melanin containing cells, with the surrounding structure remaining unaffected. This gentle laser treatment induces a response from the body in which white cells are released to clear the affected cells and rebuild the meshwork so that it functions effectively again, reducing the IOP.
Benefits
SLT effectively lowers raised IOP without the side effects or difficulty of taking eye drops. The treatment is particularly suitable for patients who cannot correctly use or are intolerant to glaucoma medications, and can also be used alongside medication to enhance the overall IOP-lowering effect.
SLT is a newer form of a long- established treatment that has the advantage of not causing any damage to the tissue treated.
The treatment procedure
Treatment takes place in the outpatient department. A nurse will check your vision and put some drops in your eye to prevent the pressure rising and to make your pupil small. These drops might cause a temporary headache and can take up to one hour to work. A doctor will take your written consent and if you have any questions, will explain further.
Once seated in front of the laser machine, which looks similar to the microscope you will have been examined with in clinic, you will have anaesthetic drops put in to numb the front of your eye. A special lens will then be placed against the front surface of your eye. This is not painful, but it might feel a little strange. During the laser treatment, you might see some flashes of light and hear clicking noises. Most patients tolerate the laser treatment well, but some might feel slight discomfort. The procedure takes between 10 and 15 minutes.
About an hour after your treatment, the pressure in your eye will be checked. You will then be given a prescription for drops to take at home for five days. We will make an appointment for you to come back to the clinic, usually one to two weeks later. This follow-up appointment is to check that your eye is settling, although the treatment might take up to eight weeks to work.
Potential side effects
Your vision will be blurred for a few hours following your laser treatment, but this will settle. The chance of your vision being permanently affected from SLT is extremely small. If you are concerned that your vision is not returning to normal, please contact us on the numbers below. You are also advised not to drive yourself to the hospital, as you will be unable to drive home.
It is possible for the pressure in your eye to increase immediately after the treatment and for there to be inflammation. In order to prevent this, we put in special drops when we treat you.
We also provide steroid drops, and occasionally extra glaucoma drops following your treatment.
Rarely, the pressure in the eye rises to a very high pressure and does not come down. If this happens, you might require surgery to lower the pressure. However, please be assured that this is a very unusual occurrence.
Success rate
Studies show a 78% success rate for SLT, with some patients responding well to the treatment, but others not responding at all. Usually, we cannot predict how well the laser will work.
This is because your response is determined by the type of glaucoma you have and the basic make-up of your eye.
If you take eye drops, you will usually need to continue these to lower the pressure after laser trabeculoplasty. It will take up to eight weeks after the laser treatment for thepressure to be reduced. You might require additional laser surgery to lower the pressure if it is not at a sufficiently low level after your first laser treatment.
The effects of the laser treatment might wear off in time – about half of all treatments stop working after five years. However, the treatment can be repeated.
Contact for further information: Please contact the main switchboard on 020 7253 3411and ask to speak to your consultant’s secretary.
video transcript
Welcome to this short information video on Selective Laser Trabeculoplasty, or SLT. Over the next few minutes, we will explain the procedure, why it has been offered to you, the benefits we hope to achieve, and the potential side effects of the treatment.
SLT is a laser treatment that helps to lower the eye pressure. It is performed in the outpatient clinic, in a designated laser room. There are no specific instructions for before the procedure, and people who are due to have the laser should continue to use their normal treatments unless specifically instructed otherwise. Half a day should be set aside for the procedure, and plans should be made for getting home with someone to help, as driving is not permitted.
You will come to your appointment and have your usual vision and eye pressure checks. Several different eye drops will be administered – these include a drop which helps reduce the eye pressure, as well as one which will numb the surface of the eye to make the laser procedure more comfortable.
Your clinician will answer any remaining questions you may have and take written consent. The laser treatment is then performed, through a slit lamp – like the microscope that is normally used for eye examinations – connected to the laser machine. A lens will be placed against the surface of the eye to improve the clinician’s view of the treatment area and stop the eye from closing. During the laser, you may hear some clicking noises and see flashes of light. The procedure takes between 5 to 7 minutes per eye and most people usually tolerate it well, although you may feel a little discomfort.
So why have you been offered this procedure? SLT is a laser procedure which applies low-energy light to specific cells in the drainage channel – called the trabecular meshwork – of the eye. The laser pulses affect only these cells, with the surrounding structure remaining unaffected. This gentle laser induces a response from the body to rebuild the trabecular meshwork so that it functions effectively again, reducing the eye pressure. The aims of the treatment vary for each individual patient and SLT is successful in around 80% of people.
Following the laser, you will then remain in clinic for 1 to 2 hours, to have your pressures checked again, before going home. If there is a significant rise in the eye pressure, this will be treated with additional drops and tablets if needed.
You will then be discharged home and will be asked to continue any usual treatment. The eyes may feel a little sore and the vision will be blurry; this is expected and will settle within 24 to 48 hours.
You will have a follow-up appointment 6 to 8 weeks later, to evaluate the success of your laser treatment and decide on the next steps.
The main benefits of SLT are that it lowers the eye pressure, which aims to help control your eye condition, and it may reduce or delay the need for eye drops or surgery.
While SLT is generally very safe, every procedure can carry some risks and side effects. Some people experience temporary blurred or cloudy vision, which usually clears within a few hours to a few days. Permanent changes to your vision are extremely rare. If you’re worried that your vision hasn’t returned to normal, please call us using the number at the end of the video.
A temporary rise in eye pressure occurs in around 1 in 10 patients. In very rare cases, the pressure may rise more significantly and may need further treatment. However, this is extremely uncommon, and your clinical team will monitor you closely to manage any changes. Inflammation can also occur and is usually treated with anti-inflammatory eye drops.
In around 20% of patients, the SLT treatment does not work. If the response is deemed to be inadequate, you may require additional treatment which may include repeat laser, eye drops, or eye surgery and this will be discussed with you by your clinician. Also, the effects of the laser treatment might wear off over time – about half of all treatments stop working after five years. However, the treatment can be repeated.
SLT is now recommended to be used as first-line therapy for those with ocular hypertension, and early open-angle glaucoma. This recommendation has come following the LiGHT Trial. This is a trial that compared eye drops with SLT as the initial treatment for these conditions in over 700 patients. The study showed that the vision and the eye pressure were similar in the two groups and that the group who had SLT required less glaucoma surgery and that some patients were spared from using glaucoma eye drops. You may have been offered SLT despite a different diagnosis, and your clinician will discuss this with you.
Thank you for watching this short informational video on SLT. If you have any questions, please feel free to raise these with your clinician at your next appointment. We hope you found this video useful and would appreciate your feedback.
Author: Emma Jones and Gus Gazzard, glaucoma department
Review date: March 2020