A patient guide to selective laser trabeculoplasty for glaucoma

Selective laser trabeculoplasty (SLT) is a procedure that is used to reduce intraocular pressure (IOP) in the eyes, in cases of glaucoma. It is used when eye drop medications are not lowering eye pressure enough or are causing significant side effects.

If your eye specialist has recommended that SLT might be the right option in your case, you may wonder how it works, if there are any risks and just how effective the treatment really is. Thankfully, one of our highly-experienced ophthalmologists Mr Vaughan Tanner answers these questions and more.

How does SLT work?

During the procedure, laser energy is applied to the drainage tissue in front of the eye, which is known as the trabecular meshwork. This causes a chemical and biological change that results in better drainage of fluid through the meshwork and out of the eye. Eventually, this results in lowering of pressure.
 

What happens on the day of the procedure?

The treatment is carried out in the laser treatment room. A nurse will check your vision and insert some anaesthetic drops together with a drop to prevent a post-laser rise in pressure. On the day of your laser treatment, you should still continue to use your regular eye medication as normal.

The specialist will put in a drop to make the pupil smaller, which might give you a headache that can be relieved with paracetamol. You will then sit at a machine similar to the one used during eye examinations, but with a special laser attached to it.

The ophthalmologist will put a special contact lens on your eye before applying the laser beam. This lens allows a clear view and helps apply the laser to the drainage channels. It is not uncommon to see some flashes of flight and hear clicking noises.

Most patients tolerate the laser well whilst some might feel slight discomfort. The procedure is painless due to the anaesthetic drops that were used to your numb your eye beforehand. It takes around 10 minutes per eye to complete.
 

Why is SLT for secondary glaucoma important?

It may take between one to three months for the full effect of treatment to appear, however, it is important to remember that this procedure is performed to save the sight that you still have. It will not restore any sight that has already been lost nor improve your sight.
 

What are the risks of SLT?

SLT has a very good safety profile in comparison to glaucoma drops. Post-operative inflammation is common but generally mild and treated with steroid eye drops.

There is an approximately 5% incidence of pressure elevation after laser, managed by glaucoma drops, which is usually resolved after 24-hours.

Rarely, the pressure in the eye rises to very high pressure and does not come down. It is under this circumstance that you might require surgery to lower the pressure, however, this is a very unusual occurrence.
 

How effective is SLT and how long does it last?

SLT lowers the intraocular pressure by about 30% when used as initial therapy. This is comparable to the pressure-lowering effect of the most powerful and commonly used glaucoma drops. This effect may be reduced if you are already on glaucoma medications. The effect will generally last between one to five years or sometimes longer.
 

Will I still need to use glaucoma medications?

Some patients' glaucoma can be controlled with just laser treatment. Other patients might require additional IOP lowering and may, therefore, need to use glaucoma medication as well. It is best to think of SLT as the equivalent to one glaucoma medication. Just as some patients will require more than one glaucoma medication, some may also require laser plus one or more glaucoma medications.

It is important to remember that SLT is not a cure for glaucoma, just as medication and surgery are not cures either.


If you would like to discuss SLT or any other concerns regarding your eye health, you can book an appointment with Mr Tanner via his Top Doctor’s profile here.