Five-year follow up of selective laser trabeculoplasty in Chinese eyes

Mechanisms of action and efficacy of argon laser trabeculoplasty and selective laser trabeculoplasty

PURPOSE OF REVIEW

Since the 1980s, laser trabeculoplasty has served as an effective way to lower intraocular pressure in patients with primary or secondary open angle glaucomas, both as an initial therapy or in conjunction with hypotensive medications. This manuscript will describe the proposed mechanisms of action of argon laser trabeculoplasty and selective laser trabeculoplasty, as well as review current studies of the therapeutic effect of these interventions.

RECENT FINDINGS

The exact mechanisms by which argon laser and selective laser trabeculoplasty lower intraocular pressure are not known. There are several theories, however, and we discuss the three most common ones: the mechanical theory, the cellular (biologic) theory, and the cell division theory. Since both lasers are applied to the same tissue and produce similar results, they most likely produce their effects in comparable ways. We also describe the results of several studies comparing these devices. Most show them to be equally effective at lowering intraocular pressure; however, there are a few circumstances when selective laser trabeculoplasty may be a better option than argon laser trabeculoplasty.

SUMMARY

Argon laser and selective laser trabeculoplasty are safe and effective procedures for lowering intraocular pressure. The results of ongoing clinical trials will help further define their role in the management of patients with open angle glaucoma.

Laser trabeculoplasty trends with the introduction of new medical treatments and selective laser trabeculoplasty

PURPOSE

To correlate trends of laser trabeculoplasties (LTPs) with the introduction of medical therapies for glaucoma and to assess whether these trends changed after the introduction of selective laser trabeculoplasty (SLT) in 2001.

METHODS

A retrospective analysis of LTP numbers, filtration surgeries, glaucoma medications dispensed, and population distribution by age in Ontario, Canada, between April 1992 and March 2005.

RESULTS

The number of LTP per 1,000 persons estimated to have primary open angle glaucoma (POAG) increased from 138.05 in 1992 to a maximum of 149.23 in 1996 (8.1% increase, 1.96% annual increase) and then steadily decreased to 70.65 in 2001 (47.3% decrease, 14% annual decrease). From 2001 to 2004, the LTP rate increased to 162.54 (230% increase, 32% annual increase). The number of filtration surgeries per 1,000 persons estimated to have POAG steadily decreased from 1996 to 2004 by 21.42% (2.4% annual decrease). The number of glaucoma medications dispensed in Ontario increased from 1992 to 2004 by 91.5% (10.5% annual increase). There were no significant correlations between the LTP rates and the new glaucoma medications rates (r=-0.35 to 0.09; P=0.34 to 0.82) or filtration surgeries rates (r=0.007; P=0.98).

CONCLUSIONS

There was a substantial reduction in the number of LTP between 1997 and 2001 coinciding, but not correlated with the introduction of medications for the treatment of glaucoma. Between 2002 and 2004 the LTP rates increased, coinciding with the introduction of SLT.

Projected cost comparison of selective laser trabeculoplasty versus glaucoma medication in the Ontario Health Insurance Plan

BACKGROUND

The projected 6-year cost comparison of primary selective laser trabeculoplasty (SLT) versus primary medical therapy in the treatment of open-angle glaucoma for Ontario patients aged 65 years or more is presented. Costs are taken from the perspective of the Ontario Health Insurance Plan at a per-patient level.

METHODS

The cost of each medication was obtained from the 2003 Ontario Drug Benefits formulary. The average annual cost of medications was determined by estimating the provincial prescription rate of glaucoma medications, with reference to both a volume-per-bottle study of these drugs and a study of pharmacy claims reports. A representative provincial prescription rate was calculated by reviewing 707 patient charts selected randomly from 5 ophthalmologic practices across Ontario. Medication therapies were categorized into mono-, bi-, and tri-drug therapy groups. The cost of SLT was analyzed under the following 2 scenarios. SLT rep 2y assumed a duration of 2 years before repeat SLT was necessary. SLT rep 3y assumed a duration of 3 years before repeat SLT was necessary. Bilateral 180 degrees SLT treatment and repeatability of SLT was assumed. The cost of surgery for patients who fail SLT or medical therapy was not accounted for in this study nor was the cost of patients who required medical therapy in conjunction with SLT.

RESULTS

In the SLT rep 2y scenario, the use of primary SLT over mono-, bi-, and tri-drug therapy produced a 6-year cumulative cost savings of 206.54 dollars, 1668.64 dollars, and 2992.67 dollars per patient, respectively. In the SLT rep 3y scenario, the use of primary SLT over mono-, bi-, and tri-drug therapy produced a 6-year cumulative cost savings of 580.52 dollars, 2042.82 dollars, and 3366.65 dollars per patient, respectively.

INTERPRETATION

Our findings suggest that SLT as primary therapy, at a per-patient level, offers a modest potential cost saving over primary medical therapy in the management of open-angle glaucoma for Ontario patients aged 65 years or more.

High Failure Rate Associated With 180?? Selective Laser Trabeculoplasty

PURPOSE

To determine the efficacy of selective laser trabeculoplasty (SLT) in a tertiary care referral center.

PATIENTS AND METHODS

In this retrospective study of selective laser trabeculoplasty performed by five physicians, 94 eyes from 94 patients were included. A majority (83/92, 90%) underwent 180 degrees selective laser trabeculoplasty. Selective laser trabeculoplasty failure was defined in two ways: (1) IOP decrease <3 mm Hg (definition one), or (2) IOP decrease <20% (definition two), on two successive visits > or =4 weeks after SLT.

RESULTS

Overall failure rates were 68% (64/94) and 75% (70/94) (by definitions one and two, respectively). By survival/life-table analysis, mean time to failure was 6 months and 5.5 months, by definitions one and two, respectively. By the end of the study (14.5 months), the failure rates were 86% and 92% by definitions one and two, respectively. By each definition, in both univariable and multivariable analysis, only lower baseline IOP was a significant predictor of failure.

CONCLUSIONS

Selective laser trabeculoplasty had an overall low success rate in our tertiary clinic population, with overall failure rates of 68% to 74% in those who underwent 180 degrees selective laser trabeculoplasty.

Glaucoma lasers: a review of the newer techniques

PURPOSE OF REVIEW

This paper serves to review the safety and efficacy of new laser techniques for the treatment of glaucoma with emphasis on those studies published within the past year.

RECENT FINDINGS

Recently published studies have reinforced the strong safety profile, and efficacy of selective laser trabeculoplasty (SLT). Endoscopic photocoagulation, while more technically challenging and more invasive, offers several advantages over transcleral cyclophotocoagulation including direct observation of treatment and therefore, fewer complications. Laser goniopuncture is a fledgling technology with, thus far, a good safety profile, and benefits that include conjunctival sparing and good treatment response. Many unanswered questions remain including long-term success rates and ideal treatment parameters.

SUMMARY

The benefits of laser in the treatment of glaucoma have been well established, and while some techniques will add to the ophthalmologists' armamentarium, others will fall into disuse as the efficacy and safety profiles of these procedures become recognized. Novel laser modalities, as well as the more traditional ones, require continued evaluation to further refine treatment parameters and to determine their long-term benefits.