Efficacy of latanoprost as an adjunct to medical therapy for residual angle-closure glaucoma after iridectomy

Guidelines for treatment of chronic primary angle-closure glaucoma

OBJECTIVE

To present a clinical practice guideline update on the medical, laser, and surgical treatment of primary angle closure glaucoma (PACG) in adults.

METHODS

Following the formulation of key questions using the PICO scheme (Patient/Problem, Intervention, Comparison, Outcome), a systematic review was performed on the literature published to date, including international clinical practice guidelines. The AMSTAR and Risk of Bias tools were used for evaluating the quality of the information. The level of evidence and grade of recommendation was established following the Scottish Intercollegiate Guidelines Network (SIGN) system.

RESULTS

Following the above methodology, recommendations of medical, laser and surgical treatment in adult PACG and levels of evidence are presented.

CONCLUSIONS

Although the level of scientific evidence for many of the questions raised is not very high, a review is presented on updated treatment recommendations for adult PACG. Among the limitations for the implementation of these recommendations is that most studies have been conducted in Asian populations, and that the effectiveness is measured almost exclusively in terms of reducing intraocular pressure, and does not include visual function, quality of life or cost-effectiveness parameters.

A review of the use of latanoprost for glaucoma since its launch

INTRODUCTION

Prostaglandins are increasingly used as first choice treatment for glaucoma because they are highly effective, lack relevant systemic side effects and require just once-daily administration. Latanoprost is an ester prodrug analog of prostaglandin F2α, which reduces intraocular pressure (IOP) by increasing uveoscleral outflow. Latanoprost 0.005% has received European and US approval as the first-line drug for reducing IOP in patients with open-angle glaucoma or ocular hypertension. Following the recent patent expiry for Xalatan®, a number of latanoprost generics have entered the glaucoma market.

AREAS COVERED

This review, achieved through PubMed and Medline research methods, describes the composition, pharmacokinetics, mode of action, efficacy, side effects and safety profile of latanoprost.

EXPERT OPINION

Latanoprost was the first prostaglandin analog introduced in glaucoma management and it dramatically changed the market of the disease thanks to its efficacy and safety. Conjunctival hyperemia, which is commonly found after latanoprost use, is associated with a minor efficacy and duration of trabeculectomy; yet, from the ophthalmologist's perspective, this side effect seems largely counterbalanced by the high efficacy and safety of this compound. It is always advisable to consider the pro-inflammatory mode of action of latanoprost because this may have negative effects in particular patients (i.e., those with uveitis and cystoid macular edema) for whom caution and close follow-up is necessary.

Medical management of angle closure glaucoma

Management of angle closure glaucoma requires an understanding of the underlying pathophysiologic mechanisms. Treatment is aimed at eliminating pupillary block and other causes of angle closure, re-opening the angle, and preventing further damage to the optic nerve by lowering intraocular pressure. Medical therapy plays an important role in the successful management of this condition. This article describes commonly used pharmacologic agents, as well as newer classes of drugs such as topical carbonic anhydrase inhibitors, prostaglandin analogues and selective alpha2- adrenergic agonists. Use of these drugs in several clinically distinct angle closure syndromes and modes of presentation are discussed.

Comparison of the Effects of Latanoprost and Travoprost on Intraocular Pressure in Chronic Angle-Closure Glaucoma

PURPOSE

The aim of this study was to compare the intraocular pressure (IOP)-lowering effect of latanoprost and travoprost as primary therapy in patients with chronic angle-closure glaucoma (CACG) after peripheral iridotomy.

METHODS

Seventy-three (73) CACG patients with IOP>19 mmHg after peripheral iridotomy and without previous antiglaucoma medication were consecutively recruited. CACG was defined as the presence of chronically elevated IOP, glaucomatous optic neuropathy, and a corresponding visual field defect in eyes with occludable angle and peripheral anterior synechiae on gonioscopy. Patients were randomly assigned to 2 groups, based on daily treatment with either latanoprost 0.005% or travoprost 0.004% in the evening for 12 weeks. The IOP was measured at 9 AM and 4 PM at baseline and at 4, 8, and 12 weeks. Between-group differences in mean diurnal IOP and IOP reduction were analyzed.

RESULTS

After 12 weeks of treatment, mean IOP for both the latanoprost and travoprost groups was significantly reduced, when compared to the baseline IOP (from 21.3+/-1.8 mmHg to 16.0+/-2.3 mmHg and 21.7+/-1.7 to 16.7+/-2.2 mmHg; P<0.001 for both). There was no significant difference in IOP reduction between the 2 treatment groups (P=0.19). At 4 and 8 weeks, the IOP changes from the baseline were statistically significant at all time points for both drugs (all P<0.001).

CONCLUSIONS

Both latanoprost and travoprost significantly reduced IOP in our sample of CACG patients after peripheral iridotomy.

Comparison of Latanoprost Monotherapy and Combined Therapy of 0.5% Timolol and 1% Dorzolamide in Chronic Primary Angle-Closure Glaucoma (CACG) in Japanese Patients

To compare the efficacy, adverse effects, and patient compliance of latanoprost monotherapy with unfixed combination therapy with 0.5% timolol maleate and 1% dorzolamide in the treatment of chronic primary angle-closure glaucoma (CACG), 36 Japanese patients with CACG following laser iridotomy (LPI) were treated for 12 weeks with instillation of latanoprost alone or with unfixed combination therapy of 0.5% timolol maleate and 1% dorzolamide hydrochloride. After 12 weeks of treatment, latanoprost reduced intraocular pressure (IOP) from 22.2 +/- 2.0 mmHg to 14.8 +/- 1.9 mmHg (33% reduction); timolol maleate and dorzolamide hydrochloride also reduced IOP from 22.5 +/- 2.2 mmHg to 17.1 +/- 2.7 mmHg (24% reduction). Latanoprost monotherapy significantly lowered IOP compared with unfixed combination therapy of 0.5% timolol maleate and 1% dorzolamide hydrochloride. Furthermore, a systemic adverse effect of bradycardia was not observed in the latanoprost monotherapy group. Concerning compliance, no significant difference was observed between the two groups. Thus, latanoprost monotherapy is more effective than unfixed combination therapy with 0.5% timolol maleate and 1% dorzolamide in the treatment of CACG following relief of pupillary block in Japanese patients.

Degree of angle closure and the intraocular pressure–lowering effect of latanoprost in subjects with chronic angle-closure glaucoma

OBJECTIVE

To examine the relationship between the configuration of the drainage angle and intraocular pressure (IOP)-lowering efficacy of latanoprost in subjects with chronic angle-closure glaucoma (CACG).

DESIGN

Prospective observational case series.

PARTICIPANTS

One hundred thirty-seven Asian subjects with CACG.

METHODS

Study subjects had participated in a 12-week, randomized, double-masked study that assessed the IOP-reducing effect of latanoprost. Chronic angle-closure glaucoma was defined as optic neuropathy with or without a visual field defect, an anterior chamber angle in which the trabecular meshwork was not visible for at least 180 degrees on gonioscopy, and evidence of peripheral anterior synechiae (PAS) in association with a chronically elevated IOP. Static and dynamic gonioscopy was performed at baseline. The angles were graded in each quadrant according to the Shaffer scheme, and the number of clock hours of PAS was recorded. The change in daily IOP (defined as the mean of the 9:00 am and 5:00 pm IOP time point values) from baseline to week 12 was analyzed and correlated with mean angle width and extent of PAS.

RESULTS

One hundred thirty-seven Asian subjects with CACG completed the study in the latanoprost-treated group. Most subjects were female (75%), and the mean age was 62.6+/-9.4 years. At baseline, the mean angle width was 0.84+/-0.55, and the mean number of clock hours of PAS was 4.67+/-2.95. After 12 weeks of treatment, latanoprost reduced IOP from 25.0+/-5.5 mmHg to 17.5+/-5.0 mmHg (P<0.001). The percent change in IOP produced by latanoprost was not associated with mean angle width (Spearman's r = 0.04, P = 0.64) or the number of clock hours of PAS (Spearman's r = -0.15, P = 0.08).

CONCLUSIONS

In subjects with CACG, the IOP-reducing efficacy of latanoprost was not affected by the degree of angle narrowing or extent of synechial angle closure.

What is the direct cost of treatment of acute primary angle closure glaucoma? The Singapore model

AIM

To estimate the cost of management of acute primary angle closure glaucoma in Singapore.

METHODS

In this cost analysis using retrospective data, the authors performed a MEDLINE search of published papers on acute primary angle closure glaucoma (APACG) in Singapore. Using information from published data, clinical management pathways were constructed and clinical outcomes identified. For each management path, costs of medical treatment, hospitalization, clinic charges, investigations, laser treatment and surgery were identified and accounted over a 5-year treatment period, using year 2002 rates.

RESULTS

Given that, in Singapore, APACG affects 12.2 per 100,000 per year (95% confidence interval [CI], 10.5-13.9) in those aged 30 and older, each annual cohort would need to pay 261,741.78 US dollars (95%CI: US$225 310.90-298 265.10) or 287,560.26 US dollars (95%CI: 247,274.04-330,624.84 US dollars), if inclusive of cataract surgery, over 5 years after the episode of APACG. In this period, individuals would have to commit between 879.45 US dollars and 2576.39 US dollars, depending on the complexity of disease and accompanying cataract surgery.

CONCLUSION

Acute primary angle closure glaucoma produces a substantial financial burden on society as well as on the individuals.

Latanoprost : an update of its use in glaucoma and ocular hypertension

Latanoprost (Xalatan) is an ester analogue of prostaglandin F2alpha that reduces intraocular pressure (IOP) by increasing uveoscleral outflow. The IOP-lowering efficacy of latanoprost 0.005% lasts for up to 24 hours after a single topical dose, which allows for a once-daily dosage regimen. In patients with ocular hypertension or open-angle glaucoma, a single drop of latanoprost 0.005% solution (about 1.5 microg) administered topically once daily reduced diurnal IOP by 22 to 39% over 1 to 12 months' treatment in well-controlled trials; efficacy was maintained during treatment periods of up to 2 years. At this dosage, latanoprost was significantly more effective than timolol 0.5% twice daily in 3 of 4 large, double-blind, randomised studies, was generally as effective as bimatoprost or travoprost, and was significantly more effective than dorzolamide, brimonidine or unoprostone. Furthermore, in patients whose IOP was poorly controlled with timolol, switching to latanoprost monotherapy was at least as effective at lowering IOP as adding dorzolamide or pilocarpine to the regimen. Latanoprost has also shown significant additive effects when used in combination with one or more other glaucoma medications. The fixed combination of latanoprost plus timolol was significantly more effective than either of its individual components in two double-blind randomised studies and more effective than the fixed combination of dorzolamide and timolol in a 3-month, evaluator-masked study. Data in patients with angle-closure glaucoma are limited, but in patients with elevated IOP after undergoing iridotomy, latanoprost 0.005% once daily was significantly more effective than timolol 0.5% twice daily at reducing IOP over 12 weeks of treatment in a large double-blind, randomised study. Latanoprost is generally well tolerated and, unlike timolol, induces minimal systemic adverse events. In well-controlled, 6-month trials, the most commonly occurring drug-related ocular events in latanoprost recipients were mild to moderate conjunctival hyperaemia (3 to 15%) and iris colour change (2 to 9%); these seldom required patient withdrawal although the latter may be permanent. Latanoprost 0.005% as a single daily drop has shown good IOP-lowering efficacy in patients with open-angle glaucoma or ocular hypertension and does not produce the cardiopulmonary adverse effects associated with beta-blockers. Thus, latanoprost is a valuable addition to the first-line treatment options for patients with open-angle glaucoma or ocular hypertension. In addition, adjunctive treatment with latanoprost in patients who are refractory to beta-blocker therapy is a viable, second-line treatment option. Although preliminary findings are promising, wider clinical experience is required to define the place of latanoprost in the treatment of angle-closure glaucoma.

Four years later: a clinical update on latanoprost

PURPOSE

Almost five years have elapsed since the introduction of latanoprost on several markets and considering the large number of publications dealing with it, the authors felt that it was worth re-evaluating the drug.

METHODS

The criterion used to select trials for inclusion in the review was: all articles mentioning the drug in common electronic data-bases; these were then screened and considered, on the basis of methodological quality.

RESULTS

Experimental data suggest that latanoprost acts by remodeling the extracellular matrix in the ciliary muscle, thus increasing the flow of aqueous humor through the ciliary muscle bundles of the uveoscleral pathway. POAG: Latanoprost persistently improves the pulsatile ocular blood flow in primary open angle glaucoma (POAG). Recent trials confirmed the greater IOP-lowering efficacy of latanoprost vs. timolol, dorzolamide, brimonidine and unoprostone. Trials lasting up to 24 months showed that latanoprost is effective in long-term treatment of POAG and ocular hypertension (OH), with no signs of loss of efficacy when compared to timolol or dorzolamide. Latanoprost provides better control of circadian IOP. Non-responders to beta-blockers should preferably be switched to latanoprost monotherapy before a combination therapy is started. The possibility of a fixed combination of latanoprost and timolol has been explored, with promising results. NTG: Latanoprost is effective in normal tension glaucoma (NTG), lowering IOP, improving pulsatile ocular blood flow and increasing ocular perfusion pressure. OTHER GLAUCOMAS: Latanoprost may provide effective IOP control in angle-closure glaucoma after iridectomy, in pigmentary glaucoma, glaucoma after cataract extraction and steroid-induced glaucoma. However, latanoprost was effective in only a minority of pediatric cases of glaucoma and is contraindicated in all forms of uveitic glaucoma.

SAFETY

In the articles reviewed, new or duration-related adverse events were reported.

Current status of prostaglandin therapy: latanoprost and unoprostone

Latanoprost, a prostaglandin F(2alpha) analog prodrug, and unoprostone, an analog of a prostaglandin metabolite, have been shown to be effective in decreasing intraocular pressure when used alone or in combination with other ocular hypotensive agents. The increase in the uveoscleral outflow and some of the side effects are probably FP-receptor mediated, which may account for some differences between the cited drugs. This article reviews the recent literature available on the clinical efficacy of these prostanoids, as well as the studies directly comparing these drugs.

Efficacy of latanoprost in reducing intraocular pressure in patients with primary angle-closure glaucoma

Two independent, prospective trials were recently conducted to assess the efficacy of latanoprost in reducing intraocular pressure (IOP) in patients with primary angle-closure glaucoma (PACG). The first study was a 2-week, randomized, double-masked comparison of latanoprost treatment and timolol treatment in patients with PACG. Patients were randomized to one of two parallel treatment groups, receiving either placebo in the morning and latanoprost 0.005% in the evening, or timolol 0.5% twice daily. The mean IOP reduction in latanoprost group was 8.8 +/- 1.1 mm Hg (mean +/- SEM, p < 0.001; 34.2%) from a mean baseline IOP of 25.7 +/- 0.9 mm Hg, and the corresponding figures for the timolol group were 5.7 +/- 0.9 mm Hg (p < 0.001; 22.6%) from a mean baseline IOP of 25.2 +/- 1.1 mm Hg. A significantly greater IOP reduction of 3.1 +/- 1.5 mm Hg (95% confidence interval: 0.1 to 6.0) was achieved in the latanoprost group compared to the timolol treatment group (p = 0.04). In the second study, latanoprost 0.005% once a day was added adjunctively to PACG patients with persistently elevated IOP after iridectomy, despite treatment with beta-blockers and pilocarpine. The IOP decreased by about 21% during the first 3 months, and showed a reduction of about 36% at the end of 1 year. At the 1-year follow-up, IOP was <20 mm Hg in all eyes. In both studies, latanoprost was well tolerated with few adverse events. These results demonstrate that latanoprost is effective in reducing IOP in patients with PACG.

The efficacy of latanoprost is independent of the width of the ciliary body face

PURPOSE

To assess the relation between the intraocular pressure-lowering efficacy of latanoprost 0.005% and the area of the ciliary body face exposed to the anterior chamber as assessed by ultrasound biomicroscopy.

PATIENTS AND METHODS

Untreated, latanoprost-naive patients with ocular hypertension or open-angle glaucoma were enrolled in this prospective clinical trial. A radial, perpendicular ultrasound biomicroscopy image at the 6-o'clock position detailing Schwalbe line, scleral spur, and iris insertion was obtained. The distances between these structures were then measured and their relations to the intraocular pressure-lowering effect of latanoprost at 1, 2, 3, and 6 months were analyzed.

RESULTS

Fifty-four eyes (54 patients) were enrolled. The mean age of participants was 60.2 +/- 13.9 years, and mean pretreatment intraocular pressure was 26.4 +/- 3.8 mm Hg. The mean intraocular pressure reduction from baseline was 7.1 mm Hg (26.9%), 7.3 (27.7%), 7.8 (29.5%), and 7.7 (29.2%) at 1, 2, 3 and 6 months, respectively. The mean distance between the scleral spur and the iris insertion was 0.14 +/- 0.08 mm (range, 0.04-0.33 mm). There was a significant correlation between intraocular pressure reduction at 1 month and trabecular meshwork height, suggesting that intraocular pressure reduction was associated with increasing trabecular meshwork height (P < 0.05). No other correlation could be found regarding intraocular pressure reduction.

CONCLUSION

Although latanoprost lowers intraocular pressure by enhancing uveoscleral outflow, its efficacy is independent of the height of the ciliary face.

Review of recent advancements in the understanding of primary angle-closure glaucoma

Primary angle-closure glaucoma is a leading cause of blindness worldwide. However, the terminology used for angle-closure in the literature is inconsistent, with inappropriate emphasis on symptomatology. A new nomenclature for primary angle-closure glaucoma focuses on the presence of end-organ damage and limits the use of the term "glaucoma" only for people who have suffered injury to the optic nerve. This review describes the various modalities of treatment for primary angle-closure glaucoma. The role and limitations of laser peripheral iridotomy in the management of the different forms of the disease are summarized. Recent developments have led to improvements in the understanding of the epidemiology, clinical course, and treatment of the condition.

The pros and cons of different prostanoids in the medical management of glaucoma

The prostaglandin analogs are new exciting drugs added to the therapeutic armamentarium for patients with glaucoma. Several studies have evaluated the ocular hypotensive properties and side effects of latanoprost in different forms of glaucoma. This drug, seems to be the most effective intraocular pressure (IOP)-reducing agent currently available, and has a low incidence of ocular and systemic side effects. Fewer data are available regarding unoprostone, but the IOP-reducing effect of this drug seems to be comparable or slightly inferior to that of timolol and it produces fewer side effects. When compared with unoprostone, latanoprost has been shown to effect a greater reduction in IOP. A major drawback to the use of prostaglandin analogues is the lack of long-term experience such as that currently available for other classes of agents.