Glaucoma Eye Laser (SLT)

Selective Laser Trabeculoplasty (SLT) is a laser procedure used to treat glaucoma by reducing the pressure in the eye. It can be used as initial treatment, instead of eye drop medications, or as additional treatment when medications do not adequately reduce your eye pressure. 

Selective Laser Trabeculoplasty (SLT) is a laser procedure used to treat glaucoma by reducing the pressure in the eye. It can be used as initial treatment, instead of eye drop medications, or as additional treatment when medications do not adequately reduce your eye pressure. SLT uses short pulses of low energy laser light to target melanin containing cells in a network of tiny channels, called the trabecular meshwork. The aim of the surgery is to help fluid drain out of your eye, reducing the intra-ocular pressure that can cause damage to the optic nerve and loss of vision. SLT procedure is not a cure for glaucoma but it can slow or stop the risk of your glaucoma progressing.

What is glaucoma?

If you have healthy eyes, the fluid in your eye (aqueous humour) flows through your pupil into the front of your eye. It then drains away through drainage channels inside your eye. These channels are situated where the cornea (clear front layer of the eye) and the iris (coloured part of the eye) meet. In some eyes, these drainage channels do not work properly so your eye pressure increases. Glaucoma affects the internal drainage system or trabecular meshwork of your eye, which causes an increase in intra-ocular pressure. This increase in pressure may injure your optic nerve and affect your vision.

Will SLT help my glaucoma?

Laser trabeculoplasty (SLT) uses a focused beam of light to treat the drainage angle of your eye. The laser makes subtle changes to the eye’s drainage system to make it easier for fluid to flow out of the front part of the eye. This lowers the pressure in your eye (intra-ocular pressure). Selective Laser Trabeculoplasty (SLT) is a good option for most people with primary open angle glaucoma, ocular hypertension or normal tension glaucoma. It is sometimes a desirable option as an intermediate step between drug management and invasive surgery. If you have open angle glaucoma and your disease is progressing in spite of medication, your doctor may recommend laser trabeculoplasty (SLT) as an initial surgical option. Your doctor may suggest laser surgery if you are on more than one eye medication or if you are intolerant to particular eye drops because of an allergy or other side effects. It may be used as a bridging therapy to delay the need for more invasive surgical procedures. On average, the procedure can lower the eye pressure by 5-7 points. It can be used in combination for those people already on topical medications but may be intolerant to the medication or require a lower target eye pressure. It can also be used as a primary treatment for people with early or mild disease who prefer to not use topical medications or feel that they may not be compliant with the every day regime of using eye drops.

It is important to remember that this procedure is done to save the sight you still have. It will not restore any sight you may have already lost, nor will it improve your sight.

How does the SLT laser work?

SLT works by using laser light to stimulate the body’s own healing response to lower your eye pressure. Using a special wavelength and energy, the laser affects only pigmented (melanin) containing cells of your eye. The laser treatment triggers 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. This improves the flow of fluid in the eye, which in turn lowers your eye pressure.

What shall I expect during the SLT procedure?

The Selective Laser Trabeculoplasty procedure is done at Bowen Eye Clinic in the purpose built laser surgery facility.  Please eat, drink and take your medication as normal before the procedure. The procedure itself only takes 10-15 mins but allow yourself to be at the clinic for 45 minutes.

On the day of the surgery, eye drops will be placed in your eye both before the laser surgery (SLT) and after to decrease the amount of fluid in your eye. This will prevent any increased pressure in your eye after laser treatment.

When your eye is completely numb your ophthalmologist will place a special contact lens on your eye to keep the lid open and allow to focus for the optimal precision of the laser beam. This is not painful but it might feel a little strange. You will be seated in the exam chair and be asked to place your chin on the frame of the laser machine, which has a chin rest and handles for you to hold on to. It is important to keep your head very still. A high-peak power beam of green light is aimed at the lens and directed onto the selected meshwork inside your eye. You may see flashes of bright green or red light and hear clicking noises of the laser machine. The laser will selectively target melanin containing cells resulting in increased fluid outflow. You will not feel any pain although some people feel a sensation. The entire procedure takes around 10-15 minutes.

What shall I expect after the procedure?

After the procedure you will be given a glaucoma drop as well as an anti-inflammatory drop to prevent post operative inflammation. You should relax for the remainder of the day.

It is normal for your vision to be blurred for a few hours, as well as for your eyes to be sensitive to light and have an achy sensation. You should arrange for someone to drive you home after your procedure.

It is important that you continue taking all of your previous medication as prescribed as it may be a few weeks before the full pressure lowering effect of the laser procedure takes place. Most people can resume their normal daily activities the day after laser surgery.

If you experience increasing redness of your eye, excessive or worsening pain or loss of vision, please contact us at Bowen Eye Clinic immediately.

How do I know if the SLT procedure has worked?

Some people can respond as soon as an hour after treatment. Others respond as much as a few months later. Your doctor will monitor your progress by measuring your intra-ocular pressure at follow up appointments. It is typical to not know whether the treatment has been successful for about four weeks.

Are there any risks with the procedure?

SLT is a safe, painless procedure. Complications are very rare. Post laser procedure inflammation is common but very mild and can be typically managed with non-steroidal anti-inflammatory medications, like ibuprofen. Occasionally, a person may have a rise in their eye pressure, however this is usually temporary and can be treated with topical medications for a short period. SLT uses an advanced laser system to target only the specific cells of the eye - those containing melanin, a natural pigment. This allows for only these cells to be affected leaving the surrounding tissue intact. As a result, your body’s own natural healing process is stimulated to enhance the outflow of the fluid in your eye, lowering the pressure in your eye.

Will I still need to take my glaucoma medication after SLT?

SLT is not a cure for glaucoma but is one of many tools to keep it under control. You will still require regular follow up appointments with your doctor who can work with you in determining the medication you may still need.

How long does the effects of SLT last?

SLT has been used since 1985 and has a proven track record for efficacy. On average, SLT can lower eye pressure by 20-30%. About  80% of people respond to treatment and the effect will last anywhere from 1-5 years. If the treatment is successful, you may be able to reduce the number of eye drops you currently use to manage your glaucoma. The laser is not permanent and the rate of the efficacy loss depends on the individual. When the treatment wears off it is possible to repeat the laser process but the effect may be reduced with repeated treatment. Unfortunately not everyone responds to treatment. At present, there is no effective way to predict who will and who will not respond.


To learn more about the SLT procedure and if you are a suitable candidate please contact Bowen Eye Clinic on 0800 69 2020 for an appointment.