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Selective Laser Trabeculoplasty (SLT)


Selective laser trabeculoplasty (SLT) is a procedure which can be performed to help reduce the intraocular pressure for patients with glaucoma. It is generally a mild treatment which is performed in an outpatient surgery center. The effect typically lasts from one to five years and the treatment can be repeated if appropriate.

In SLT treatment, a focused light ray is directed at the drainage structure called the trabecular meshwork. The special wavelength and energy of the laser light stimulates the body’s natural healing (immune) response. Over several weeks this response promotes improved fluid flow from the eye, resulting in pressure lowering. Because the laser energy only interacts with pigmented cells, there is minimal thermal damage which could lead to scar tissue formation (more common with ALT-Argon Laser Trabeculoplasty).

It may take several weeks for the laser effect to develop. The effect can last one to five years, after which, the effect seems to fade. The exact time course varies somewhat for each person. Therefore, it is important to have your pressures monitored at regular intervals after the procedure.

How to Prepare

Being prepared helps your treatment go smoothly and comfortably. We recommend the following steps:

  • Plan to be available at the surgery center for several hours on the day of the treatment.
  • Eat a good breakfast and take your medicines including your glaucoma medicines in the usual way.
  • You might plan to bring a book or other entertainment (there is a TV and coffee in the waiting room at the surgery center).
  • There is no need to stop blood thinners such as aspirin or Motrin; if you use a stronger blood thinner let the technician know during your preop.
  • Bring some dark glasses for the drive home. Use your judgment as to whether or not you would like a driver – many patients drive themselves.

About the Laser Treatment

Selective Laser Trabeculoplasty is performed in an outpatient setting. Since there are several pre- and postoperative steps involved, you should plan to be available for several hours on the day of the treatment. These steps, although time consuming, help make the procedure safe and comfortable. The basic process involves the preoperative evaluation and preparation, the treatment, a recovery period, and the postoperative check.

In the preoperative step, the technician will check your pressure and review your medical history. You will be given a permit (consent form) about the procedure which you will need to read and sign. If you cannot see to read the permit the technician, or a family member, may read it to you. You will have an opportunity to ask questions or share any concerns you may have with your doctor prior to the procedure. The technician will place a preoperative eye drop in your eye and you will be instructed where to sit while the medicine takes effect. After the appropriate time interval, you will be escorted to the treatment room.

In the treatment room, anesthetic eye drops will be placed on your eye and you will be seated at the laser instrument. This instrument looks similar to the slit lamp used to check your eyes in the exam rooms. A hand-held lens is placed on your eye by your doctor. It is filled with a sticky jelly which cushions the lens as it rests on the eye. This feels a little bulky and sticky but is not uncomfortable. The lens helps your doctor have a magnified and clearer view into the drainage angle. It also helps you to refrain from blinking or moving your eye during the procedure. At this point, it is best to use the eye not being treated to stare at your doctor’s ear. As the laser treatment is applied there may be a mild prickling or tingling sensation. The doctor may adjust the power as needed for a good tissue response and can reduce it if needed for your comfort. Your doctor may also ask you to move your eye a little between applications. The doctor can move treatment away from a particularly sensitive area in your eye, if necessary. These adjustments help keep you comfortable and work toward giving you the best possible opportunity for a successful result.

Once the treatment is completed the lens is removed and the eye area is rinsed with a refreshing eye wash. Post operative eye drops are instilled. After that you, will be asked to sit in the waiting room. You will be called once again by the technician to have your intraocular pressure checked prior to discharge from the surgery center.

Initially after the treatment your eye sight will be blurry from the flashing of the laser light. There is often a feeling of fullness or mild swelling in the eye area. These conditions usually clear substantially during the recovery period. However, as the anesthetic wears off, the eye may become a little sore and scratchy. This effect, most commonly, is from rubbing by the hand-held lens as it rests on the eye.

Most patients can drive themselves home after they have been cleared postoperatively. If possible it is best to go home and rest after the procedure. It is alright to stop for a snack or meal if you are hungry. Most patients become tired later, however, so planning for a quiet rest period is helpful. The eye may remain scratchy and a little light sensitive throughout the day and the vision may be slightly blurred. During this time it is helpful to avoid bright light by staying inside or wearing dark glasses. It is perfectly alright to read and watch TV, but be prepared to rest and close your eyes during these activities if needed. You may use lubricating tear drops, an ice pack, and Tylenol or Motrin if desired.

Most patients are comfortably able to resume their regular schedule and activities the day following the procedure. Be sure to continue your usual glaucoma medicine as before. You will not have any restriction of your physical activities. For some, the eye does not become sore until 24 hours later. This soreness can last up to 3-4 days. Again, tylenol or motrin along with an ice pack on the eye can be used to improve your comfort. There will be a second postoperative check 3-7 days after the procedure. Please call your doctor’s office to schedule this appointment if it has not already been scheduled.


Success Rate and Complications

SLT treatment is given to help control the intraocular pressure in an effort to stabilize your glaucoma. It may augment the benefit from your current medicine or it may reduce the need for some medicine. Your doctor will advise you of any changes you should make in your medication schedule during your follow up visits. Typically, the effect does wear off after one to five years. Additional treatment may be recommended at that time.

A successful response to SLT treatment occurs in 50–80 % of patients. Studies suggest that a higher success rate occurs for eyes that have had no prior surgery of any kind. The most common complication is a postoperative spike in the intraocular pressure. Typically the postoperative pressure fluctuates a little. Rarely a significant rise in pressure occurs. This is why it is necessary to check your pressure in the office after recovering for an interval. If a pressure spike is detected it can then be addressed promptly. Mild inflammation resulting in some discomfort or tenderness can also occasionally develop postoperatively. This usually responds to Tylenol or Motrin.

SLT is a form of laser treatment for the eye used to help glaucoma. It is different from LASIK treatment in that it is not used to improve vision or to reduce the need for glasses. It can, however, help save eye sight which might otherwise be lost. It is preventive rather than restorative.