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Selective laser trabeculoplasty
Last reviewed: 19.10.2021
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The method of selective laser trabeculoplasty
Pulsating double neodymium aluminum-yttrium garnet laser (AIG) applied Latina in 1998 with trabeculoplasty. It was designed to selectively affect pigmented tissue and to minimize side effects. Unlike a continuous-wave argon laser, a selective laser does not damage the trabecular zone thermally. Because of the fixed size of 400 μm points, the 50 μm points used for ALT seem very small. Thus, the distances between the laser exposure points for selective laser trabeculoplasty (SLT) are much more compact, practically merging. The size of the points with selective laser trabeculoplasty is so large that one beam covers the entire angle. When using a laser, the number of pulses (50-60), the magnitude of the angle of impact (180-360 °), and the power (up to 0.8 J) can be varied.
The final value of the power is determined by the reaction of the tissue to the initial laser application. The discoloration of the pigmented trabecular network with a slight formation of bubbles as a result of evaporation is an ideal option. When the formation of bubbles is expressed, the power is reduced. The use of low power is highly recommended in operations at highly pigmented corners, as is the case with pigment glaucoma.
Mechanism of action of selective laser trabeculoplasty
Scanning electron microscopy reveals the difference between the use of an argon laser with the "melting" of trabecular beams and a selective laser with a minimum. If any, structural disturbance of the trabecular network. Thus, the theory of mechanical stretching is not used when the selective intraocular pressure laser is applied. In cultures of cells of the trabecular network in vitro, an action was taken by an argon and selective laser. The application of an argon laser damaged both pigmented and non-pigmented cells. Unlike the argon laser, the selective laser acted only on pigmented cells.
The involvement of macrophages in the work of the outflow system was shown in animal models and in the eyes of a person. Macrophages can release chemical mediators that control the rate of outflow. It is claimed that increasing the concentration of interleukins after laser exposure improves the outflow of moisture.
The effectiveness of selective laser trabeculoplasty
Comparative studies have confirmed that neodymium aluminum-yttrium garnet laser and selective laser trabeculoplasty equally effectively reduce the intraocular pressure in the eyes that can not be treated with medicament. Preliminary data confirm that the initial use of selective laser trabeculoplasty prior to the introduction of drug therapy reduces intraocular pressure intraocular pressure by 24-30% of the initial level. Because of the absence of structural damage in selective laser trabeculoplasty, repeated attempts at laser therapy should theoretically be safe, potentially reducing intraocular pressure. A successful reduction in intraocular pressure after selective laser trabeculoplasty was reported in patients who had previously failed ALT.