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pigmented cells of the trabecular meshwork without provoking thermal damage to adjacent nonpigmented cells. The absence of these unwanted thermal effects is the result of the affinity of the 532 nm wavelength for the chromophore/target represented by melanin, but also by the pulse duration of a few nanoseconds, which is shorter than the time required — around 1 ms — for the conversion of radiant electromagnetic energy into heat by the chromophore melanin in pigmented cells. When radiant energy is released rapidly, as it is with a nanosecond-range pulse, only a minimal part is converted into heat. This limits the thermal dissipation and coagulative damage, not only in the treatment zone but also in the surrounding tissues.

The success of SLT depends on a precise, highly sensitive mechanism that involves the destruction of certain cells and the sparing of others, thus preserving the structural integrity of the trabecular meshwork. The injured cells release cytokines that recruit macrophages and provoke other changes. The result is increased outflow, a reduction of IOP that occurs within a few hours, the birth of new cells, and lasting increases in the outflow capacity.

Results

The efficacy and safety of SLT have been clearly demonstrated. Thirty months after treatment, success was observed in 77% of the patients with chronic open-angle glaucoma and in 74% of those with exfoliation glaucoma (Latina, 1998). Maximum pressure-reducing effects were observed 7–14 days after treatment, with an IOP of approximately 10 mmHg during the first postoperative hours. However, the presence of an inflammatory reaction was documented, and the IOP during the first few hours was higher than that observed after ALT. Six months after treatment, the pressure-reducing effect of SLT is comparable to that of laser trabeculoplasty.

In a population-based study, response rates treatment were slightly different from those associated with treatment of 3601 to 1801 (Nagar et al., 2005) 901 SLT is generally not effective. 1801 and 3601 SLT appears to be an effective treatment

with approximately 60% of eyes achieving an IOP reduction of 30% or more.

In conclusion, SLT is an interesting method and an excellent alternative to ALT, and it should be considered a first-line treatment for patients with chronic open-angle glaucoma (Latina et al., 2002; Martinez-de-la-Casa, 2004). SLT can be repeated, even after laser trabeculoplasty. It seems to produce better results than ALT in eyes with nonpigmented angles and is also associated with a lower risk of for trabecular damage.

LASER iridoplasty

Peripheral iridoplasty, also known as gonioplasty, involves photocoagulative treatment of the peripheral iris based on the induction of thermal contraction of the stroma of the iris, which widens the angular recess.

Indications

The European Glaucoma Society guidelines recommend the use of iridoplasty in the following conditions:

Plateau iris syndrome.

Preparation for laser trabeculoplasty when the iridocorneal angle is narrow and difficult to see.

Angle closure in nanophthalmus.

Contraindications

Treatment is not advisable if the following conditions are present:

Severe edema or corneal opacity that impairs visualization of the peripheral iris.

Marked gerontoxon.

Athalamia.

Angle closure secondary to synechiae.

Treatment technique

Laser iridoplasty is done under topical anesthesia after instillation of a miotic to distend the