What are the different types of lasers for glaucoma?
There are three main types of lasers for glaucoma, although you could say there are actually four because some of them can be used in surgery. The types of lasers we can talk about are:
- YAG laser
- ARGON laser
- Selective laser (SLT)
Traditionally, there were YAG and ARGON lasers, which were mainly used to change the shape of the iris because sometimes changing the shape of the iris can be beneficial. In recent years, starting in the mid-1990s, a variant of these lasers was developed, known as the selective trabeculoplasty laser (SLT), which makes it possible to treat glaucoma with a minimally invasive technique.
How do they work and what is their impact on the disease?
In narrow-angle glaucoma (one of the types of glaucoma) lasers work either by producing a change in the shape of the iris (iridioplasty), which is performed with the ARGON laser or, on the other hand, with YAG lasers, iridotomies (microperforations in the iris) can be performed.
Also with ARGON lasers, trabeculoplasties can be performed, which lower the tension, but modify the trabecular meshwork, which is the portion through which the aqueous humor exits the eye. In addition, in open-angle glaucomas, the resistance to the outflow of this fluid is what causes high tension glaucomas.
Selective laser trabeculopasty (SLT) was developed because it was less aggressive and simpler than the previous one and can be repeated over time. SLT attempts to target the same part of the trabecular meshwork of the aqueous humor filtration portion and to lower the pressure by modifying it more slowly, but less drastically.
The main risks of laser treatment in glaucoma are occasional pressure increases, which are prevented by treating with hypotensors, as well as inflammation, which is also prevented by using topical anti-inflammatory drugs in drops. The treatment is very innocuous, so significant inflammation or hypertension would be rare.
With traditional lasers, sometimes, there may be small bleedings that usually resolve spontaneously and that may not occur with SLT.
What are the advantages of laser glaucoma treatment?
The advantages of laser treatment in glaucoma are:
- It is less aggressive than surgery and laser has been reliably shown in research to have fewer side effects than eye drops.
- It is a treatment capable of lowering the pressure in most open-angle glaucoma eyes.
- Trabeculoplasty has fewer side effects than eye drops in the short and long term. Eye drops produce a degree of chronic conjunctivitis, both because of their active ingredient that irritates the surface of the eyes, and because of the excipients or preservatives they contain, which in the long run produce irritation and dry eye symptoms. In addition to further compromise the outcome of future interventions by promoting conjunctival scarring.
- Laser treatments are not perfect, as they are less powerful than surgery but can control most open angle glaucoma without local side effects.
Also, some eye drops have consequences in the rest of the body. There is no eye drop that is totally innocuous. Some reduce the heart rate, others reduce the diameter of the bronchi and can produce in bronchial or asthmatic patients, asthma crises or dyspnea and may not be tolerable, others produce kidney stones, others certain unpleasant tastes, insomnia, etc.
The laser lacks these effects and reduces the tension, controlling glaucoma. Therefore, the best option at present, and, whenever possible, is to use the laser and use eye drops in addition (if necessary).