Since their development over 60 years ago, lasers have revolutionized many fields, particularly medicine. Lasers allow us to easily and safely perform procedures which were once much more invasive, or not possible at all.
A laser is basically a very focused beam of light energy. The color of light emitted by a laser is determined by the type of material used to produce it. This material can be a gas, a liquid, a solid, or a semiconductor such as a diode. When the material inside the laser tube is energized, it produces light of a very specific wavelength, or color. In ophthalmology, lasers range in wavelength from infrared to ultraviolet. The wavelength determines how the laser will affect different cells and tissues within the body. The ability to control the exact amount of energy delivered by the laser makes it the perfect tool to perform precise, delicate surgery within the eye.
Trabeculoplasty is a laser procedure performed for the treatment of open angle glaucoma. It is often recommended as an option when intraocular pressure (IOP) is not adequately controlled by medications alone, but can be performed as an initial means of lowering IOP in appropriate patients as well. A recent study, the LiGHT trial, concluded that laser trabeculoplasty is as safe and effective, and likely more cost-effective, than medications when used as a first-line treatment for glaucoma.
The procedure tends to reduce pressure by about 20 to 30 percent, or roughly the equivalent of one glaucoma medication. Trabeculoplasty demonstrates up to 80% success in lowering IOP, depending on certain characteristics of the patient being treated, such as number of glaucoma medications used, amount of pigment within the eye’s drainage canal, and type of glaucoma. The effects of this procedure are not permanent and tend to wear off after two to five years. Trabeculoplasty can be repeated when the treatment effect begins to fade, often with good pressure-lowering results.
Two forms of trabeculoplasty are available today. The original procedure, described in 1979, was performed using an argon laser, though currently a solid-state diode laser is often employed. These lasers produce light in the visible spectrum with a blue-green color. This type of treatment is often called “argon laser trabeculoplasty,” or ALT. ALT is a time-tested procedure which has been performed for over 40 years. The greatest drawback to ALT is that it can only be performed two to three times on an eye, as further treatments can actually cause injury.
A newer version of the procedure, known as “selective laser trabeculoplasty,” or SLT, achieves the same goal using a frequency-doubled neodymium:YAG laser, also producing light in the blue-green spectrum. Because the amount of energy delivered by this laser is less than that in ALT, the procedure can theoretically be repeated as many times as desired without risk of injury to the eye. Multiply repeated treatments performed years apart are often successful. Presently, we perform primarily the SLT procedure, based upon its better safety profile and ability to be repeated multiple times, as needed.
Trabeculoplasty will not cure glaucoma. Damage to the optic nerve cannot be reversed. The goal of trabeculoplasty, as with all treatments for glaucoma, is to lower intraocular pressure and prevent the further loss of vision. In some cases, glaucoma medications may be eliminated, however many patients will need to continue all pre-treatment eye drops to maintain adequately low IOP.
Trabeculoplasty is not 100% effective at lowering intraocular pressure. Results often vary depending upon the type of glaucoma, number and type of eye drops being taken, and other conditions affecting the eye. Your surgeon will discuss your specific situation and will provide appropriate guidance.
Laser trabeculoplasty is a short, in-office procedure. Most patients are able to drive to and from their appointment alone. Upon arrival, your vision and IOP will be tested. Your eye will then be numbed with an eyedrop, and additional drops may be given to help prevent post-operative pressure spikes. You will then be seated at the laser, which looks very similar to the microscope used to examine your eyes during a normal appointment. A contact lens will be placed on your eye to help focus the laser. A series of between 50 and 100 laser pulses will then be applied, during which time you will see flashes of light and may experience mild discomfort or burning. The contact lens will then be removed, and the gel used to help keep the contact lens in place will be washed away. Additional drops may be given, if necessary.
IOP elevations, or spikes, occur occasionally after the procedure and may need to be treated with extra medication. Therefore, you will be asked to wait or return approximately one hour after your treatment for a check of the pressure.
The full impact of SLT is typically seen in four to six weeks, and a follow-up appointment will be scheduled accordingly.
Mild discomfort, irritation, light sensitivity, and blurred vision are typical immediately after the procedure, and such mild symptoms may continue for two to four days afterwards. Post-operative anti-inflammatory medication (eye drops) will be provided for use for several days.
Complications from SLT are uncommon, with mild corneal or intraocular inflammation occurring infrequently, potentially requiring additional treatment. Complications causing loss of vision are exceedingly rare.