a mild steroid like fluoromethalone 0.1% (FML™) or loteprednol 0.5% (Lotemax™) q.i.d. for 1 week. The patient may be seen 1–2 hours after the treatment to monitor for IOP elevation, and if the eye is quiet and with reasonable IOP, the patient may be seen after several weeks. Many surgeons do not use any anti-inflammatory agents after SLT since the postoperative inflammation is rarely a problem and the authors have noted a less vigorous IOP reduction when anti-inflammatory agents are used.

The patient returns for an evaluation 1 month and 3 months after the procedure to evaluate and monitor IOP. The patient’s preoperative medication regime continues unaltered postoperatively, including in the immediate postoperative period. Maximum effects from ALT may not be seen until 6 weeks whereas maximum response to SLT may take as much as 3 months. Repeat SLT should not be performed until at least 3 months after the initial SLT to be sure that enough time has been given for the response to take place. If the IOP decreases enough, the surgeon may decide to decrease the patient’s medication use.

Outcomes

Kramer and Noecker first studied the effects of ALT and SLT on human eye-bank eyes.54 Evaluation of the trabecular meshwork of eyes which had undergone ALT revealed crater formation in the uveal meshwork, coagulative damage with disruption of the collagen beams and fibrinous exudates, and lysis of endothelial cells. By comparison, the trabecular meshwork of eyes which had undergone SLT showed no evidence of coagulative damage or disruption of the corneoscleral or uveal trabecular beam structure. Selective laser trabeculoplasty therefore preserves the meshwork for future medical, laser, or surgical intervention, if necessary. Additionally, eyes which had previously undergone failed ALT demonstrated a significantly greater reduction in IOP when treated with SLT than those treated with repeat ALT.17

A preliminary clinical trial studying the safety and efficacy of SLT in treating primary open-angle glaucoma demonstrated a mean IOP decrease of 30% at 1 day, 27% at 8 weeks, and 29% at 49 weeks.55 No serious adverse effects were reported. Melamed and co-workers performed the procedure in 45 eyes of 31 patients, and recorded a decrease in IOP from 25.5 2.5 mmHg to 17.9 2.8 mmHg, or 30%.56 No serious adverse effects were related to SLT.56 Several multicenter, prospective clinical trials have been conducted which further demonstrate the efficacy and safety of SLT. Pressure reductions ranged from 2.85 to 10.6 mmHg with follow-up periods of 6 weeks to 26 months.18 Subsequent studies have compared the safety and efficacy of ALT and SLT in treating various types of glaucoma.

In their comparison of the long-term success rates of SLT and ALT, Juzych and co-workers found that both techniques are similarly effective in lowering IOP over a 5-year follow-up period.57 Likewise, in a clinical study of 40 patients, 20 of whom were treated with SLT (180°) and 20 with ALT (180°), Martinez-de-la-Casa and colleagues found that at 6 months following treatment, pressure reduction was similar in both groups.58 In addition, the energy released during treatment and inflammation in the anterior chamber in the immediate postoperative period was significantly lower for the SLT procedure, as was pain reported by the patients during treatment.58 Similarly, in a prospective trial with a follow-up period of 36 months, there was no significant difference between IOP reductions in patients who had undergone ALT and those who had undergone SLT.17

Contraindications

Contraindications to ALT include inadequate visualization of the trabecular meshwork, hazy media, closure of the iridocorneal angle, corneal edema, uveitic glaucoma, juvenile glaucoma (usually), patient age of 35 years or less, and a need for IOP-lowering greater than 7–10 mmHg.

While inflammatory glaucoma is considered a contraindication for ALT, in a study of 130 eyes of 87 patients with allergic, uveitic, and post-transplantation diagnoses, IOP was reduced by 4 mmHg or more in 56% of eyes treated with SLT.59

A heavily pigmented trabecular meshwork, especially combined with previous ALT, may be a contraindication to SLT. In a retrospective, non-comparative case series of 4 eyes which presented with IOP spikes after undergoing SLT, Harasymowycz and colleagues found that all eyes were characterized by heavy trabecular meshwork pigmentation, and 50% had previously undergone ALT.60 The authors suggest that eyes with heavy pigmentation and a history of previous ALT should be considered at increased risk for IOP spikes post SLT.60

As initial therapy

The Glaucoma Laser Trial demonstrated the efficacy of ALT as initial therapy for open-angle glaucoma.13 Selective laser trabeculoplasty may prove equally effective as initial therapy.To evaluate the potential of SLT as a replacement for medications, Francis and colleagues performed SLT inferiorly on 66 eyes of 66 patients with medically controlled open-angle or exfoliative glaucoma.61 At 12 months, 87% of patients achieved a significant reduction in medications (mean reduction at 12 months: 1.5), while maintaining a previously determined target IOP.61 Further study is needed to determine if clinically significant IOP control is possible using SLT as primary treatment.

Predictors of outcome

While it has been suggested that pigmentation may contribute to determining the outcome of SLT, several studies have shown otherwise. Hodge and associates evaluated whether any characteristics of 72 patients, including age, race, sex, pigmentation, or other risk factors for glaucoma, were predictors of successful SLT at 1 year (successful SLT defined as a reduction in IOP 20%).62 Only baseline IOP was a significant predictor of successful SLT.

Aphakic and pseudophakic open-angle glaucoma

Laser trabeculoplasty is generally less effective in aphakic eyes,30 but when it is successful the decrease in IOP in aphakic open-angle glaucoma is similar to that for chronic open-angle glaucoma (average, approximately 7 mmHg). Preliminary data indicate that LTP may be as effective in pseudophakic eyes with posterior chamber lenses as it is in phakic eyes. Cataract surgery after LTP seems not to have a deleterious effect on IOP control. Laser trabeculosplasty performed before cataract surgery may be more effective than that performed afterward.

Complications

Intraocular pressure elevation

Few complications are associated with LTP (Table 31-2).48–50 Up to 50% of patients, however, experience a transient IOP spike