Laser treatment for Glaucoma:  SLT & YAG PI

Selective Laser Trabeculoplasty (SLT)

 

Selective Laser Trabeculoplasty (SLT) is a simple yet highly effective laser procedure that reduces the intraocular pressure associated with glaucoma. 

SLT can be used as the first treatment once glaucoma is diagnosed, avoiding the usual need for daily eye drops. It may be used in patients already on eye drops to allow them to stop their eye drops if found to be inconvenient or if side effects are a problem. Finally, it may be used in an attempt to avoid the need for glaucoma surgery if eye drops are not controlling the pressure well enough.

 

SLT uses short pulses of low-energy light to target the melanin, or pigment, in specific cells of the affected eye. In response, the body's natural healing mechanicsms go to work to rebuild these cells. This rebuilding process improves drainage and lowers intraocular pressure. The surrounding, non-pigmented cells — as well as the rest of the eye structure — are untouched and undamaged.

 

What happens during the treatment?

 

SLT is done in the outpatient clinic as a day treatment. Prior to treatment, eye drops are administered to prepare the eye and provide mild anaesthesia, numbing the front of the eye. A special contact lens will be positioned onto the eye which helps to aim the laser and hold the eyelids out of the way. Then, gentle pulses of light are delivered through a specially designed microscope. The entire process takes just 5 to 10 minutes. 

 

After the treatment another eye drop is put in to prevent any immediate rise in the eye pressure which sometimes may occur.  You may then be treated with anti-inflammatory eye drops. The eye pressure is then checked 6 weeks later.

 

How often can I have SLT done?

 

SLT is gentle and non-invasive — which allows the procedure to be repeated if necessary. By comparison, repeat treatments of previous approaches in laser therapy were either extremely limited or not possible.

 

Who is SLT suitable for?

 

If you fit in to any of the following categories, you may be good candidate for SLT:

 

  • If you have primary open-angle, pseudoexfoliation, or pigmentary glaucoma. (If you're not sure, ask your ophthalmologist.)
  • If you are intolerant of glaucoma medications, or have difficulty taking them as prescribed.
  • If you are currently undergoing glaucoma drug therapy and wish to combine it with SLT.
  • It is difficult for you to commit to regular follow-up treatments, due to finances, lack of transportation, or other limitations.
  • If you have a history of failed ALT (argon laser trabeculoplasty) treatments.

 

What if SLT doesn't work for me?

 

SLT lowers intraocular pressure by an average of 25 percent in up to 75 percent of patients treated. Unfortunately it is not possible to specifically predict for an individual what are the chances of success.It does wear off in some patients and the success rate 5 years later is approximately 50%.

 

For those that do not respond, other forms of treatment, including traditional drug therapy or surgery can still be highly effective.

 

YAG Laser Peripheral Iridotomies (YAG PI)

 

What does "narrow angles" mean?

 

The eye is a hollow structure, and is filled with fluid, which inflates the eye and gives the eye its shape. Fluid is made inside the eye, and drains out of the eye at a relatively constant rate, so the pressure of the eye remains stable. However, in some people, especially people who are farsighted, the drain inside the eye (called "the angle") can start to close. This is referred to as "narrow angles".

 

Narrow angles are a risk factor for angle-closure glaucoma, the type of glaucoma that can have both a sudden, painful onset or a slow progressive course. Although not everyone with narrow angles actually develops glaucoma, careful evaluation of the angle structure can identify those at risk. The angle structure is determined by an examination called "gonioscopy" which is performed with a special contact lens.

 

What happens if the angle (the drain inside the eye) closes?

 

If the angle closes, then fluid made inside the eye cannot drain out. Imagine what would happen if you kept inflating a football after it was already filled with air. Inside the eye, if the angle closes, then fluid will build up in the eye – causing increased eye pressure. If the pressure in the eye becomes too high, your eye may become painful, and may lead to permanent vision loss.

 

Can anatomically narrow angles be treated?

 

Yes. A laser iridotomy can prevent the damage that angle-closure glaucoma can cause before the actual disease sets in. A laser beam (the YAG laser) is used to make a microscopic hole in the iris (the colored part of the eye). The hole (iridotomy) creates a "release valve" and an alternate channel for fluid to flow through the eye is produced. The iridotomy decreases the risk of angle closure and vision loss from glaucoma.

 

What happens if I have anatomically narrow angles but I do not have the laser iridotomy?

 

There is a small risk (1-2%/year) that you will develop angle closure, and risk experiencing a sudden episode of severe eye pain and blurring of vision. Once this occurs it can be more difficult to treat. There is also the chance that the angle will close slowly, cause damage and slowly increases pressure in the eye. There is often no pain with chronic angle closure, and you can loose vision without being aware that your eye pressure is high.

 

 What happens during the treatment?

 

A YAG PI is done in the outpatient clinic as a day treatment. Prior to treatment, eye drops are administered to prepare the eye and provide mild anaesthesia, numbing the front of the eye. A special contact lens will be positioned onto the eye which helps to aim the laser and hold the eyelids out of the way. The laser procedure is brief taking between 1-2 minutes for the entire procedure. There are no restrictions on your activities after the procedure.

 

After the treatment another eye drop is put in to prevent any immediate rise in the eye pressure which sometimes may occur. You may then be treated with anti-inflammatory eye drops. Your eye is then checked 1-2 weeks later.

 

What are the risks of YAG laser iridotomy?

 

You may feel brief "twinges" of discomfort during the laser procedure. There is rarely a small amount of bleeding inside the eye, but this resolves quickly. Some people may have discomfort with light for a few days after the procedure.  There is a small risk of increased eye pressure, glare and halos after the procedure.

 

Will a YAG laser iridotomy improve my vision?

 

No. YAG laser iridotomy is performed to prevent angle closure glaucoma. It is not laser vision correction.

 

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This website exists to provide further information about ocular conditions to patients, and their families, optometrists and GPs.

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