A controlled five-year follow-up study of laser trabeculoplasty as primary therapy for open-angle glaucoma

Laser trabeculoplasty in newly diagnosed multi-treated glaucoma patients

PURPOSE

To evaluate the intraocular pressure (IOP)-lowering effect of laser trabeculoplasty (LTP) in eyes which IOP had been substantially reduced by intensive topical treatment for one week.

METHODS

Patients with newly diagnosed open-angle glaucoma were randomized to treatment with three IOP-lowering substances. One week later, 360° argon or selective LTP was performed. IOP was measured before LTP and at one-, three-, six- and 12-month post-LTP. The patients were part of the Glaucoma Intensive Treatment Study (GITS).

RESULTS

Mean IOP (± SD) in 152 eyes of 122 patients was 14.0 (± 3.5) mmHg just before LTP. For every mmHg higher IOP prior to LTP, the IOP was reduced by an additional 0.6 mmHg at 12 months. The IOP was significantly reduced at all follow-up visits from -2.6 (± 3.1) mmHg at one month to -2.1 (± 3.8) mmHg at 12 months in eyes with pre-LTP IOP ≥ 15 mmHg, while no significant IOP reduction was seen in eyes with pre-LTP IOP < 15 mmHg. Older age, argon LTP and male sex were associated with larger IOP reduction after 12 months, whereas presence of exfoliation syndrome was associated with a smaller IOP reduction. No severe complications were reported.

CONCLUSION

Success of LTP was highly dependent on the IOP level prior to LTP treatment. A sustained significant IOP reduction was seen in eyes with pre-LTP IOP ≥ 15 mmHg whereas no such effect was seen in eyes with pre-LTP IOP < 15 mmHg. Thus, LTP can be considered in eyes with multi-treatment when target pressure of < 15 mmHg is not achieved.

Monitoring and management of the patient with pseudoexfoliation syndrome: current perspectives

Pseudoexfoliation syndrome (PES) is a complex and age-related systemic disorder characterized by the progressive accumulation and granular deposition of pseudoexfoliative material in various intraocular and extraocular tissues. The diagnosis of PES is so important because it is a major risk factor for complications during cataract surgery and the most frequent cause of secondary glaucoma. In addition to ocular complications, PES is related with numerous systemic abnormalities, for which the list is growing steadily. Therefore, management and monitoring of patients with PES are crucial. The aim of this paper was to review current perspectives on monitoring patients with PES and addressing management of ocular and systemic associations of this clinically important and biologically fascinating disease.

Latanoprost versus timolol as first choice therapy in patients with ocular hypertension. A cost-effectiveness analysis

PURPOSE

To determine the cost-effectiveness of ocular hypertension (OH) treatment initiated with latanoprost compared to timolol.

METHODS

Two strategies for OH therapy are modelled, (1) 'starting with timolol' and (2) 'starting with latanoprost'. Therapy can be maintained or changed dependent on the achieved intraocular pressure (IOP) and side-effects. Adjustments of therapy to reach a target pressure involve monotherapy, combination therapy and laser. Four drugs are used: latanoprost, timolol, brimonidine and dorzolamide. Once the adjustments of therapy are completed, lifelong follow-up with IOP-dependent conversion to glaucoma and progression to blindness are modelled. Direct medical costs are assigned. The IOP-lowering effect of drugs is based on meta-analyses and applied by Monte Carlo simulation to a hypothetical cohort of patients with OH. The characteristics of the cohort, including the initial IOP distribution, are based on data of 1000 patients.

RESULTS

The IOP decreased from 25,4 mm Hg (mean) to 16.7 (±0.017) mm Hg (strategy 1) and to 16.5 (±0.013) mm Hg (strategy 2). Costs per patient within 15 months of therapy were € 367 and € 469, respectively. Lifetime blindness and costs were 0.0334 years and € 3,514 (strategy 1) and 0.0318 years and € 4,397 (strategy 2). Incremental costs per year of vision saved for strategy (2) in comparison with strategy (1) amount to, given the uncertainties in the model, approximately € 537,000.

CONCLUSION

For saving 1 year of vision, high costs are needed when OH therapy is initiated with latanoprost compared to timolol, when the cost price of latanoprost remains high.

Cataract and glaucoma surgery in pseudoexfoliation syndrome: a review

Pseudoexfoliation syndrome is a risk factor in cataract surgery because of the increased weakness of zonular apparatus and reduced pupillary dilatation. The surgical outcome of using phacoemulsification in the central zone, inducing minimal stress on the zonules, inserting a capsular tension ring in selected cases, and stretching the pupil mechanically in eyes with miotic pupils, may turn out to be uneventful in most cases. Postoperative fibrosis with subsequent shrinkage of the capsule is increased in these eyes, and these centripetal forces will further loosen the zonular fibres. Late in-the-bag intraocular lens dislocation is therefore anticipated to become a growing problem in the future. Despite the dysfunctioning of the blood-aqueous barrier in eyes with pseudoexfoliation syndrome, the frequency of postoperative inflammatory reaction is low due to the improvements made in surgical technique and equipment in recent years. Glaucoma frequently occurs in eyes with pseudoexfoliation syndrome. Compared with primary open-angle glaucoma, optic damage is more pronounced in these eyes at the time of diagnosis and response to medical therapy is poorer. Although responses to argon laser therapy and filtering surgery are roughly similar between the two types of glaucoma, there are indications that primary laser trabeculoplasty has a higher success rate in pseudoexfoliation glaucoma than in primary open-angle glaucoma.

Management of glaucoma: focus on pharmacological therapy

Glaucoma represents a major cause of vision loss throughout the world. Primary open-angle glaucoma, the most common form of glaucoma, is a chronic, progressive disease often, though not always, accompanied by elevated intraocular pressure (IOP). In this disorder, retinal ganglion cell loss and excavation of the optic nerve head produce characteristic peripheral visual field deficits. Patients with normal-tension glaucoma present with typical visual field and optic nerve head changes, without a documented history of elevated IOP. A variety of secondary causes, such as pigment dispersion syndrome and ocular trauma, can result in glaucoma as well. Treatment of all forms of glaucoma consists of reducing IOP. With proper treatment, progression of this disease can often be delayed or prevented. Treatment options for glaucoma include medications, laser therapy and incisional surgery. Laser techniques for the reduction of IOP include argon laser trabeculoplasty and selective laser trabeculoplasty. Both techniques work by increasing outflow of aqueous humour through the trabecular meshwork. Surgical options for glaucoma treatment include trabeculectomy, glaucoma drainage tube implantation and ciliary body cyclodestruction. While each of these types of procedures is effective at lowering IOP, therapy usually begins with medications. Medications lower IOP either by reducing the production or by increasing the rate of outflow of aqueous humour within the eye. Currently, there are five major classes of drugs used for the treatment of glaucoma: (i) cholinergics (acetylcholine receptor agonists); (ii) adrenoceptor agonists; (iii) carbonic anhydrase inhibitors (CAIs); (iv) beta-adrenoceptor antagonists; and (v) prostaglandin analogues (PGAs). Treatment typically begins with the selection of an agent for IOP reduction. Although beta-adrenoceptor antagonists are still commonly used by many clinicians, the PGAs are playing an increasingly important role in the first-line therapy of glaucoma. Adjunctive agents, such as alpha-adrenoceptor agonists and CAIs are often effective at providing additional reduction in IOP for patients not controlled on monotherapy. As with any chronic disease, effective treatment depends on minimising the adverse effects of therapy and maximising patient compliance. The introduction of a variety of well tolerated and potent medications over the past few years now allows the clinician to choose a treatment regimen on an individual patient basis and thereby treat this disorder more effectively.

Methodologic rigor of clinical trials on surgical management of eyes with coexisting cataract and glaucoma

OBJECTIVE

To assess the methodologic quality of published studies of the surgical management of coexisting cataract and glaucoma.

DESIGN

Literature review and analysis.

METHOD

We performed a systematic search of the literature to identify all English language articles pertaining to the surgical management of coexisting cataract and glaucoma in adults. Quality assessment was performed on all randomized controlled trials, nonrandomized controlled trials, and cohort studies. Overall quality scores and scores for individual methodologic domains were based on the evaluations of two experienced investigators who independently reviewed articles using an objective quality assessment form.

MAIN OUTCOME MEASURES

Quality in each of five domains (representativeness, bias and confounding, intervention description, outcomes and follow-up, and statistical quality and interpretation) measured as the percentage of methodologic criteria met by each study.

RESULTS

Thirty-six randomized controlled trials and 45 other studies were evaluated. The mean quality score for the randomized, controlled clinical trials was 63% (range, 11%-88%), and for the other studies the score was 45% (range, 3%-83%). The mean domain scores were 65% for description of therapy (range, 0%-100%), 62% for statistical analysis (range, 0%-100%), 58% for representativeness (range, 0%-94%), 49% for outcomes assessment (range, 0%-83%), and 30% for bias and confounding (range, 0%-83%). Twenty-five of the studies (31%) received a score of 0% in the bias and confounding domain for not randomizing patients, not masking the observers to treatment group, and not having equivalent groups at baseline.

CONCLUSIONS

Greater methodologic rigor and more detailed reporting of study results, particularly in the area of bias and confounding, could improve the quality of published clinical studies assessing the surgical management of coexisting cataract and glaucoma.

A review of argon and selective laser trabeculoplasty as primary treatments of open-angle glaucoma

It is generally accepted within the ophthalmic community that medical therapy is the preferred primary treatment in open-angle glaucoma, followed by laser trabeculoplasty if the medical therapy is unsuccessful, with surgery employed more as an end-stage option when these avenues have been exhausted. This review discusses the efficacy of argon laser trabeculoplasty, alone and in comparison with medical therapy as a primary treatment of glaucoma. It will also discuss the new laser technique, selective laser trabeculoplasty.

Argon and low energy, pulsed Nd:YAG laser trabeculoplasty. A prospective, comparative clinical and morphological study

Argon laser trabeculoplasty (ALT; 1.0 W, 0.1 sec, 50 microns) was performed in right eyes, and low energy, Q-switched Nd:YAG laser trabeculoplasty (Nd:YAGLT; 1.1-4.8 mJ/pulse) in left eyes of 14 patients with primary open-angle glaucoma and in one patient with juvenile glaucoma. The pre-laser intraocular pressure (IOP) was medically uncontrollable (IOP > 21 mmHg). The interocular pressure difference varied between 0 and 3 mmHg. In 9 patients IOP decreased to less than 22 mmHg (success) in both eyes. No statistically significant difference has been revealed with paired t-test in the degree of IOP decrease between ALT and Nd:YAGLT treated eyes during the 1-18 months' follow-up. Treatment variables of Nd:YAGLT had no statistically significant effect on the duration of the post-laser success with Cox-regression. In 4 patients both treatments were ineffective (IOP > 21 mmHg). In 2 patients ALT was successful but Nd:YAGLT was ineffective. In three cases of early bilateral laser failure (IOP > 21 mmHg at the first month visit) trabeculectomy was performed on both eyes in the third post-laser month. Following ALT the uveoscleral meshwork was severely destroyed in the area of the laser spots, and the surrounding collagen fibres were heat-damaged. The meshwork between the laser spots was covered by a membrane formed by migrating endothelial cells. In the uveoscleral meshwork Nd:YAGLT induced severe focal damage surrounded by circumscript shrinkage and scarring. The juxtacanalicular tissue remained free of laser induced damage. No endothelial membrane was present. The results suggest that low energy, Q-switched Nd:YAGLT may represent an alternative method of glaucoma laser surgery.

Primary argon laser trabeculoplasty vs. pilocarpine. Short-term effects

This is a prospective study of 82 newly discovered patients with simplex or capsular glaucoma from two centres, collected between 1984 and 1989 and selected at random for primary treatment by either laser or pilocarpine. Preliminary two-year follow-up shows that primary laser treatment gives a significantly higher number of patients where the intraocular pressure is successfully controlled. Primary argon laser trabeculoplasty has been carried out in 40 patients. The first treatment was given to either the upper or to the lower half of the trabecular meshwork. In the second treatment after one month the other half was treated. In both groups the first treatment gave the highest pressure reduction. The somewhat higher pressure reduction after upper treatment versus lower was insignificant. The degree of trabecular pigmentation did not influence the two month follow-up result, neither did the type of glaucoma. Of the eyes treated with laser, peripheral anterior synechiae could be seen in 18%. Acute intraocular pressure rises greater than 5 mmHg occurred in 21% of the eyes after the first treatment and in 37% after the second treatment. Pressure rises greater than 10 mmHg occurred in 5% after the first and in 10% after the second treatment. No pressure-lowering substances were given. Considering that 16% of the eyes had an intraocular pressure that was higher than baseline pressure even 6 h after either first or second treatment, it is recommended that a pressure-lowering medication on the day of treatment should be administered.

Pilocarpine to prevent acute pressure increase following primary laser trabeculoplasty

The effect of pilocarpine pretreatment on the transient pressure elevations immediately following primary laser trabeculoplasty was investigated in a prospective, randomised study. Fifty eyes of 50 patients, 33 with exfoliative and 17 with simple glaucoma, were treated in 360 degrees of the trabecular meshwork. The mean maximum pressure increase was 2.4 (SD = 4.4)mm Hg with pilocarpine pretreatment and 12.8 (SD = 11.2)mm Hg without pretreatment (p less than 0.05). Except in two cases, all peak pressures appeared during the first two hours after treatment. The degree of chamber angle pigmentation was predictive of the magnitude of the post laser hypertensive pressure response in eyes without pretreatment (p less than 0.05).

Laser trabeculoplasty

Over a decade, laser trabeculoplasty has evolved from being a novel new treatment to one that is a commonly accepted intervention in the management of open-angle glaucoma. Despite its widespread use, however, there are still many unanswered questions about laser trabeculoplasty, including its mechanism of action and the ideal treatment parameters. In this review, we will discuss the history of the technique, the clinical experience, and some of the experimental studies that have been conducted to answer the questions regarding its mechanism of action.

Long-term efficacy of primary laser trabeculoplasty

Sixty glaucomatous eyes of 60 patients treated with laser trabeculoplasty as primary therapy were reviewed retrospectively. There were 42 eyes with capsular glaucoma and 18 with simple glaucoma. The mean prelaser intraocular pressure (IOP) was 35.2 (SD = 6.5) mmHg. Success was defined as IOP less than or equal to 22 mmHg without medication. The probability of success was 0.73 at 1 year, 0.66 at 2 years, 0.57 at 3 years, and 0.50 at 4 years. Three eyes experienced progressive visual field loss or disc damage in spite of an intraocular pressure below 22 mmHg without medication. High prelaser pressure and the severity of the visual field defects were significant predictors of treatment failure.

Primary argon laser trabeculoplasty after pretreatment with timolol. A safe and economic therapy of early glaucoma

In the treatment of glaucoma there are advantages and disadvantages associated with both medical, surgical and laser therapy. Early pressure rise has been found to be the main complication after laser treatment. In the present study primary argon laser trabeculoplasty (PALT) was carried out in 180 degrees of the trabecular meshwork with an effect of 0.4-0.6 W, after instillation of one drop of timolol 0.5%. Among our 27 newly diagnosed glaucoma patients no pressure rise or iritic reaction was detected. More than 50% of the patients were still managed with an intraocular pressure below 21 mmHg without medical or surgical treatment after 2 years. In addition to being virtually without side-effects this treatment modality is time saving and cost effective, and a great part of the patients may avoid medical therapy.

The immediate pressure response to primary laser trabeculoplasty--a comparison of one- and two-stage treatment

The immediate pressure response to primary LTP was studied prospectively in 40 eyes randomised to one- and two-stage treatment in 360 degrees of the trabecular meshwork. There were 26 eyes with glaucoma capsulare and 14 with glaucoma simplex. Mean prelaser IOP was 32.8 mmHg in the former, and 35.5 mmHg in the latter group. The frequency and magnitude of postlaser pressure increase were the same in both groups when taking into consideration the pressure spikes in both 180 degrees sessions. The pressure increase was higher than in earlier reports on LTP in presurgical glaucoma patients on maximum medication. Almost all IOP elevations appeared during the first 2 h following laser treatment. The results were the same in both groups 6 months after LTP.

The place of trabeculectomy in the management of primary open-angle glaucoma and factors favouring success

Medical treatment has always been the mainstay in the management of primary open-angle glaucoma (POAG). Surgical intervention has been reserved for cases with intraocular pressures uncontrolled on medical therapy and/or progression of visual field loss. Following the introduction of trabeculectomy, there was a move toward earlier surgery in POAG with some advocating it as a primary procedure. However, others have emphasised the complications and unpredictability of trabeculectomy and use it only as a last resort. In this article the literature is reviewed and the factors that prevent complications and help ensure a successful result in trabeculectomy are considered. While the role of trabeculectomy as a primary procedure in POAG is debatable, the authors favour earlier surgical intervention rather than using surgery as a last resort.

Laser trabeculoplasty versus medication treatment as primary therapy for glaucoma

The first-year results of a 5-year prospective randomized follow-up study on 39 glaucoma patients, of whom 19 patients received laser trabeculoplasty and 20 patients medication therapy as primary treatment of their newly detected open-angle glaucoma, are presented. The optic disc changes were recorded by measuring the magnification corrected neuroretinal rim area from stereoscopic optic disc photographs and the visual field changes with an automated perimeter. There were no statistically significant differences in success rate, intraocular pressure reduction, and optic disc or visual field changes between the two groups during the first year of follow-up. In half of the laser treated patients the intraocular pressure was below 22 mmHg without medication treatment. Many patients in the medication group required frequent modifications of their therapy. Laser trabeculoplasty has an important role as primary therapy in glaucoma.