Before and after the laser treatment apraclonidine 0.5% or brimonidine 0.2% should be added to the patient’s normal antiglaucoma regimen to prevent or attenuate iop spikes (Chen and Ang, 2001). Topical anesthesia with 4% benoxinate or 4% oxybuprocaine is generally sufficient.

During the immediate postoperative period (4–7 days), local steroid treatment or topical nonsteroidal anti-inflammatory drugs (NSAIDs) should be applied 3–4 times a day. NSAIDs can also be administered 24 h before the treatment to reduce the release of prostaglandins that are responsible for the inflammatory response (Hotchkiss et al., 1984). The patient should be reexamined 24 h after treatment and at 4–6 weeks to evaluate the effects of the treatment and make sure there are no complications. The European Glaucoma Society recommends closer follow-up (1 and 3 h after treatment) for patients with serious visual-field defects, markedly elevated pretreatment IOPs, exfoliation syndrome, one-eyed patients, and those who have had previous laser trabeculoplasties.

Complications of the treatment

The most common complication of laser trabeculoplasty is the acute, transient elevation of IOP, which is evident immediately after treatment. Thirty to fifty percent of all patients experience IOP increases of 10 mmHg or more 1–7 h after treatment (Krupin et al., 1987; Tuulonen et al., 1989). The incidence and the magnitude of these pressure spikes seem to be reduced when ALT is performed in two 50-spot sessions. The literature contains rare reports of ocular hypertension with onset several weeks after trabeculoplasty, including some that were associated with posttreatment uveitis.

PAS are found in 12–47% of treated eyes, depending on the various statistics; the mean frequency reported in the Glaucoma Laser Trial was 33% (Glaucoma Laser Trial Research Group, 1995). According to this study, synechiae formation is associated with intense pigmentation of the trabecular meshwork; other studies suggest that this complication is dependent on the site of treatment (posterior versus the root of the iris).

Iritis, hemorrhages, transient reductions in visual acuity caused by the gonioscopy fluid (used

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to enhance contact), and corneal lesions are rare complications.

Efficacy

The effects of the laser treatment are not immediate; 4–6 weeks must pass before the results can be properly evaluated. In 84% of all patients who undergo trabeculoplasty, significant reductions in IOP are observed within 12 months of treatment. However, the rate decreases as the duration of follow-up increases, reaching 55% 5 years after treatment (Fellman et al., 1984; Lunde, 1993). In two other long-term studies, the effect of ALT persisted for 1 year in 67–80% of treated eyes, for 5 years in 35–50%, and for 10 years in 5–30%, with an annual loss of efficacy in the range of 6–10% (Shingleton and Richter, 1987; Spaeth and Baez, 1992).

Patients who have had ALT thus have to be followed constantly, with ongoing monitoring of clinical examinations. It is difficult to predict if or when increases in IOP will occur: they may appear after months or even years of follow-up. Retreatment carries a considerably reduced likelihood of success compared with the initial ALT. In these cases, surgical treatment should probably be considered.

Selective laser trabeculoplasty

Selective laser trabeculoplasty (SLT) is a recently introduced technique that was developed by Latina and Park (1995). In March of 2001, it was approved by the Food and Drug Administration for treatment of open-angle glaucoma. In terms of both efficacy and safety, SLT has been judged to be clinically equivalent to ALT, which was previously used for patients with open-angle glaucoma. It is based on the use of a Q-switched frequency-doubled 532 nm Nd:YAG laser with a spot diameter of 400 mm, a power range of 0.2–2.0 mJ, and a pulse duration of 3–10 ns; it can be used to treat 1801 of the trabecular meshwork (50 spots) or the full circumference (100 spots).

Latina and Park showed that a Q-switched laser emitting at 532 nm with a pulse duration in the nanosecond range can selectively lyse the