Statistical analysis plan for the Laser-1st versus Drops-1st for Glaucoma and Ocular Hypertension Trial (LiGHT): a multi-centre randomised controlled trial

The Impact of Baseline Intraocular Pressure on Initial Treatment Response in the LiGHT Trial: Selective Laser Trabeculoplasty versus Medication

PURPOSE

The Laser in Glaucoma and Ocular Hypertension Trial demonstrated the efficacy and safety of selective laser trabeculoplasty (SLT) compared with topical hypotensive medication as first-line therapy for ocular hypertension and open-angle glaucoma. This substudy explored the impact of pretreatment (baseline) intraocular pressure (IOP) on treatment response.

DESIGN

Post hoc analysis of randomized control trial data.

PARTICIPANTS

A total of 1146 eyes from 662 patients were included in this analysis: 559 eyes in the SLT group and 587 in the medication group.

METHODS

Intraocular pressure reduction at 8 weeks after treatment with either SLT or prostaglandin analog (PGA) eye drops was assessed at different levels of baseline IOP, and the groups were compared. Differences in absolute and percentage IOP lowering between SLT and PGA groups were tested with a linear mixed-effects model. Differences in the probability of achieving ≥ 20% IOP lowering between SLT and PGA groups, at different levels of baseline IOP, were estimated using a logistic mixed-effects model.

MAIN OUTCOME MEASURE

Intraocular pressure-lowering response to SLT versus PGA eye drops.

RESULTS

Mean IOP was not significantly different between the groups at baseline or 8 weeks after treatment initiation. Both treatments showed greater IOP lowering at higher baseline IOP and less IOP lowering at lower baseline IOP. Selective laser trabeculoplasty tended to achieve more IOP lowering than PGA drops at higher baseline IOP. Prostaglandin analog drops performed better at lower baseline IOP, and the difference compared with SLT, in terms of percentage IOP reduction, was significant at baseline IOP of ≤ 17 mmHg. A significant difference was found in the relationship between baseline IOP and probability of ≥ 20% IOP lowering between the two treatments (P = 0.01), with SLT being more successful than PGA at baseline IOP of more than 22.5 mmHg.

CONCLUSIONS

We confirm previous reports of greater IOP lowering with higher baseline IOP for both SLT and PGA drops. In treatment-naïve eyes, at higher baseline IOP, SLT was more successful at achieving ≥ 20% IOP lowering than PGA drops. At lower baseline IOP, a statistically greater percentage, but not absolute, IOP lowering was seen with PGA drops compared with SLT, although the clinical significance of this is uncertain.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial: Six-Year Results of Primary Selective Laser Trabeculoplasty versus Eye Drops for the Treatment of Glaucoma and Ocular Hypertension

PURPOSE

The Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial has shown selective laser trabeculoplasty (SLT) to be clinically and cost-effective as a primary treatment of open-angle glaucoma (OAG) and ocular hypertension (OHT) at 3 years. This article reports health-related quality of life (HRQoL) and clinical effectiveness of initial treatment with SLT compared with intraocular pressure (IOP)-lowering eye drops after 6 years of treatment.

DESIGN

Prospective, multicenter randomized controlled trial.

PARTICIPANTS

Treatment-naive eyes with OAG or OHT initially treated with SLT or IOP-lowering drops.

METHODS

Patients were allocated randomly to initial SLT or eye drops. After the initial 3 years of the trial, patients in the SLT arm were permitted a third SLT if necessary; patients in the drops arm were allowed SLT as a treatment switch or escalation. This study is registered at controlled-trials.com (identifier, ISRCTN32038223).

MAIN OUTCOME MEASURES

The primary outcome was HRQoL at 6 years; secondary outcomes were clinical effectiveness and adverse events.

RESULTS

Of the 692 patients completing 3 years in the LiGHT Trial, 633 patients (91.5%) entered the extension, and 524 patients completed 6 years in the trial (82.8% of those entering the extension phase). At 6 years, no significant differences were found for the EuroQol EQ-5D 5 Levels, Glaucoma Utility Index, and Glaucoma Quality of Life-15 (P > 0.05 for all). The SLT arm showed better Glaucoma Symptom Scale scores than the drops arm (83.6 ± 18.1 vs. 81.3 ± 17.3, respectively). Of eyes in the SLT arm, 69.8% remained at or less than the target IOP without the need for medical or surgical treatment. More eyes in the drops arm exhibited disease progression (26.8% vs. 19.6%, respectively; P = 0.006). Trabeculectomy was required in 32 eyes in the drops arm compared with 13 eyes in the SLT arm (P < 0.001); more cataract surgeries occurred in the drops arm (95 compared with 57 eyes; P = 0.03). No serious laser-related adverse events occurred.

CONCLUSIONS

Selective laser trabeculoplasty is a safe treatment for OAG and OHT, providing better long-term disease control than initial drop therapy, with reduced need for incisional glaucoma and cataract surgery over 6 years.

Laser trabeculoplasty for open-angle glaucoma and ocular hypertension

BACKGROUND

Open-angle glaucoma (OAG) is an important cause of blindness worldwide. Laser trabeculoplasty, a treatment modality, still does not have a clear position in the treatment sequence.

OBJECTIVES

To assess the effects of laser trabeculoplasty for treating OAG and ocular hypertension (OHT) when compared to medication, glaucoma surgery or no intervention. We also wished to compare the effectiveness of different laser trabeculoplasty technologies for treating OAG and OHT.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2021, Issue 10); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; LILACS, ClinicalTrials.gov and the WHO ICTRP. The date of the search was 28 October 2021. We also contacted researchers in the field.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing laser trabeculoplasty with no intervention, with medical treatment, or with surgery in people with OAG or OHT. We also included trials comparing different types of laser trabeculoplasty technologies.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. Two authors screened search results and extracted data independently. We considered the following outcomes at 24 months: failure to control intraocular pressure (IOP), failure to stabilise visual field progression, failure to stabilise optic neuropathy progression, adverse effects, quality of life, and costs. We graded the 'certainty' of the evidence using GRADE.

MAIN RESULTS

We included 40 studies (5613 eyes of 4028 people) in this review. The majority of the studies were conducted in Europe and in the USA. Most of the studies were at risk of performance and/or detection bias as they were unmasked. None of the studies were judged as having low risk of bias for all domains. We did not identify any studies of laser trabeculoplasty alone versus no intervention. Laser trabeculoplasty versus medication Fourteen studies compared laser trabeculoplasty with medication in either people with primary OAG (7 studies) or primary or secondary OAG (7 studies); five of the 14 studies also included participants with OHT. Six studies used argon laser trabeculoplasty and eight studies used selective laser trabeculoplasty. There was considerable clinical and methodological diversity in these studies leading to statistical heterogeneity in results for the primary outcome "failure to control IOP" at 24 months.  Risk ratios (RRs) ranged from 0.43 in favour of laser trabeculoplasty to 1.87 in favour of medication (5 studies, I2 = 89%). Studies of argon laser compared with medication were more likely to show a beneficial effect compared with studies of selective laser (test for interaction P = 0.0001) but the argon laser studies were older and the medication comparator group in those studies may have been less effective. We considered this to be low-certainty evidence because the trials were at risk of bias (they were not masked) and there was unexplained heterogeneity. There was evidence from two studies (624 eyes) that argon laser treatment was associated with less failure to stabilise visual field progression compared with medication (7% versus 11%, RR 0.70, 95% CI 0.42 to 1.16) at 24 months and one further large recent study of selective laser also reported a reduced risk of failure at 48 months (17% versus 26%) RR 0.65, 95% CI 0.52 to 0.81, 1178 eyes). We judged this outcome as moderate-certainty evidence, downgrading for risk of bias. There was only very low-certainty evidence on optic neuropathy progression. Adverse effects were more commonly seen in the laser trabeculoplasty group including peripheral anterior synechiae (PAS) associated with argon laser (32% versus 26%, RR 11.74, 95% CI 5.94 to 23.22; 624 eyes; 2 RCTs; low-certainty evidence); 5% of participants treated with laser in three studies of selective laser group had early IOP spikes (moderate-certainty evidence). One UK-based study provided moderate-certainty evidence that laser trabeculoplasty was more cost-effective.  Laser trabeculoplasty versus trabeculectomy Three studies compared laser trabeculoplasty with trabeculectomy. All three studies enrolled participants with OAG (primary or secondary) and used argon laser. People receiving laser trabeculoplasty may have a higher risk of uncontrolled IOP at 24 months compared with people receiving trabeculectomy (16% versus 8%, RR 2.12, 95% CI 1.44 to 3.11; 901 eyes; 2 RCTs). We judged this to be low-certainty evidence because of risk of bias (trials were not masked) and there was inconsistency between the two trials (I2 = 68%). There was limited evidence on visual field progression suggesting a higher risk of failure with laser trabeculoplasty. There was no information on optic neuropathy progression, quality of life or costs. PAS formation and IOP spikes were not reported but in one study trabeculectomy was associated with an increased risk of cataract (RR 1.78, 95% CI 1.46 to 2.16) (very low-certainty evidence).

AUTHORS' CONCLUSIONS

Laser trabeculoplasty may work better than topical medication in slowing down the progression of open-angle glaucoma (rate of visual field loss) and may be similar to modern eye drops in controlling eye pressure at a lower cost. It is not associated with serious unwanted effects, particularly for the newer types of trabeculoplasty, such as selective laser trabeculoplasty.

Patient-reported Outcomes, Functional Assessment, and Utility Values in Glaucoma

In clinical glaucoma research, the measurement of patient reported outcomes, functional assessment of disability, and health economic impact is critical. However, valid, time-efficient and comprehensive tools are not available and several current instruments lack in the appropriate precision for measuring the various dimensions of glaucoma-related quality of life (QoL), including functioning and mobility. Furthermore, statistical methods are inconsistently and sometimes incorrectly used in otherwise sound clinical studies. Standardizing and improving methods of patient-centered data collection and analysis in glaucoma studies are imperative. This paper outlines recommendations and provides a discussion of some of the pertinent issues relating to the optimization of patient-reported outcomes research in glaucoma.

Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial

BACKGROUND

Primary open angle glaucoma and ocular hypertension are habitually treated with eye drops that lower intraocular pressure. Selective laser trabeculoplasty is a safe alternative but is rarely used as first-line treatment. We compared the two.

METHODS

In this observer-masked, randomised controlled trial treatment-naive patients with open angle glaucoma or ocular hypertension and no ocular comorbidities were recruited between 2012 and 2014 at six UK hospitals. They were randomly allocated (web-based randomisation) to initial selective laser trabeculoplasty or to eye drops. An objective target intraocular pressure was set according to glaucoma severity. The primary outcome was health-related quality of life (HRQoL) at 3 years (assessed by EQ-5D). Secondary outcomes were cost and cost-effectiveness, disease-specific HRQoL, clinical effectiveness, and safety. Analysis was by intention to treat. This study is registered at controlled-trials.com (ISRCTN32038223).

FINDINGS

Of 718 patients enrolled, 356 were randomised to the selective laser trabeculoplasty and 362 to the eye drops group. 652 (91%) returned the primary outcome questionnaire at 36 months. Average EQ-5D score was 0·89 (SD 0·18) in the selective laser trabeculoplasty group versus 0·90 (SD 0·16) in the eye drops group, with no significant difference (difference 0·01, 95% CI -0·01 to 0·03; p=0·23). At 36 months, 74·2% (95% CI 69·3-78·6) of patients in the selective laser trabeculoplasty group required no drops to maintain intraocular pressure at target. Eyes of patients in the selective laser trabeculoplasty group were within target intracoluar pressure at more visits (93·0%) than in the eye drops group (91·3%), with glaucoma surgery to lower intraocular pressure required in none versus 11 patients. Over 36 months, from an ophthalmology cost perspective, there was a 97% probability of selective laser trabeculoplasty as first treatment being more cost-effective than eye drops first at a willingness to pay of £20 000 per quality-adjusted life-year gained.

INTERPRETATION

Selective laser trabeculoplasty should be offered as a first-line treatment for open angle glaucoma and ocular hypertension, supporting a change in clinical practice.

FUNDING

National Institute for Health Research, Health and Technology Assessment Programme.

Laser in Glaucoma and Ocular Hypertension (LiGHT) trial. A multicentre, randomised controlled trial: design and methodology

PURPOSE

The Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial aims to establish whether initial treatment with selective laser trabeculoplasty (SLT) is superior to initial treatment with topical medication for primary open-angle glaucoma (POAG) or ocular hypertension (OHT).

DESIGN

The LiGHT Trial is a prospective, unmasked, multicentre, pragmatic, randomised controlled trial. 718 previously untreated patients with POAG or OHT were recruited at six collaborating centres in the UK between 2012 and 2014. The trial comprises two treatment arms: initial SLT followed by conventional medical therapy as required, and medical therapy without laser therapy. Randomisation was provided online by a web-based randomisation service. Participants will be monitored for 3 years, according to routine clinical practice. The target intraocular pressure (IOP) was set at baseline according to an algorithm, based on disease severity and lifetime risk of loss of vision at recruitment, and subsequently adjusted on the basis of IOP control, optic disc and visual field. The primary outcome measure is health-related quality of life (HRQL) (EQ-5D five-level). Secondary outcomes are treatment pathway cost and cost-effectiveness, Glaucoma Utility Index, Glaucoma Symptom Scale, Glaucoma Quality of Life, objective measures of pathway effectiveness, visual function and safety profiles and concordance. A single main analysis will be performed at the end of the trial on an intention-to-treat basis.

CONCLUSIONS

The LiGHT Trial is a multicentre, pragmatic, randomised clinical trial that will provide valuable data on the relative HRQL, clinical effectiveness and cost-effectiveness of SLT and topical IOP-lowering medication.

TRIAL REGISTRATION NUMBER

ISRCTN32038223, Pre-results.

Self-Monitoring Symptoms in Glaucoma: A Feasibility Study of a Web-Based Diary Tool

Purpose. Glaucoma patients annually spend only a few hours in an eye clinic but spend more than 5000 waking hours engaged in everything else. We propose that patients could self-monitor changes in visual symptoms providing valuable between clinic information; we test the hypothesis that this is feasible using a web-based diary tool. Methods. Ten glaucoma patients with a range of visual field loss took part in an eight-week pilot study. After completing a series of baseline tests, volunteers were prompted to monitor symptoms every three days and complete a diary about their vision during daily life using a bespoke web-based diary tool. Response to an end of a study questionnaire about the usefulness of the exercise was a main outcome measure. Results. Eight of the 10 patients rated the monitoring scheme to be “valuable” or “very valuable.” Completion rate to items was excellent (96%). Themes from a qualitative synthesis of the diary entries related to behavioural aspects of glaucoma. One patient concluded that a constant focus on monitoring symptoms led to negative feelings. Conclusions. A web-based diary tool for monitoring self-reported glaucoma symptoms is practically feasible. The tool must be carefully designed to ensure participants are benefitting, and it is not increasing anxiety.

Perioperative medications for preventing temporarily increased intraocular pressure after laser trabeculoplasty

BACKGROUND

Glaucoma is the international leading cause of irreversible blindness. Intraocular pressure (IOP) is the only currently known modifiable risk factor; it can be reduced by medications, incisional surgery, or laser trabeculoplasty (LTP). LTP reduces IOP by 25% to 30% from baseline, but early acute IOP elevation after LTP is a common adverse effect. Most of these IOP elevations are transient, but temporarily elevated IOP may cause further optic nerve damage, worsening of glaucoma requiring additional therapy, and permanent vision loss. Antihypertensive prophylaxis with medications such as acetazolamide, apraclonidine, brimonidine, dipivefrin, pilocarpine, and timolol have been recommended to blunt and treat the postoperative IOP spike and associated pain and discomfort. Conversely, other researchers have observed that early postoperative IOP rise happens regardless of whether people receive perioperative glaucoma medications. It is unclear whether perioperative administration of antiglaucoma medications may be helpful in preventing or reducing the occurrence of postoperative IOP elevation.

OBJECTIVES

To assess the effectiveness of medications administered perioperatively to prevent temporarily increased intraocular pressure (IOP) after laser trabeculoplasty (LTP) in people with open-angle glaucoma (OAG).

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 11), MEDLINE Ovid (1946 to 18 November 2016), Embase.com (1947 to 18 November 2016), PubMed (1948 to 18 November 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 18 November 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com); last searched 17 September 2013, ClinicalTrials.gov (www.clinicaltrials.gov); searched 18 November 2016 and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 18 November 2016. We did not use any date or language restrictions.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in which participants with OAG received LTP. We included trials which compared any antiglaucoma medication with no medication, one type of antiglaucoma medication compared with another type of antiglaucoma medication, or different timings of medication.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened records retrieved by the database searches, assessed the risk of bias, and abstracted data. We graded the certainty of the evidence using GRADE.

MAIN RESULTS

We included 22 trials that analyzed 2112 participants and identified no ongoing trials. We performed several comparisons of outcomes: one comparison of any antiglaucoma medication versus no medication or placebo, three comparisons of one antiglaucoma medication versus a different antiglaucoma mediation, and one comparison of antiglaucoma medication given before LTP to the same antiglaucoma medication given after LTP. Only one of the included trials used selective laser trabeculoplasty (SLT); the remaining trials used argon laser trabeculoplasty (ALT). Risk of bias issues were primarily in detection bias, reporting bias, and other potential bias due to studies funded by industry. Two potentially relevant studies are awaiting classification due to needing translation.In the comparison of any medication versus no medication/placebo, there was moderate-certainty evidence that the medication group had a lower risk of IOP increase of 10 mmHg or greater within two hours compared with the no medication/placebo group (risk ratio (RR) 0.05, 95% confidence interval (CI) 0.01 to 0.20). This trend favoring medication continued between two and 24 hours, but the evidence was of low and very low-certainty for an IOP increase of 5 mmHg or greater (RR 0.17, 95% CI 0.09 to 0.31) and 10 mmHg or greater (RR 0.22, 95% CI 0.11 to 0.42). Medication was favored over placebo/no medication with moderate-certainty in reducing IOP from the pre-LTP measurements for both within two hours and between two and 24 hours. At two hours, the mean difference (MD) in IOP between the medication group and the placebo/no medication group was -7.43 mmHg (95% CI -10.60 to -4.27); at between two and 24 hours, the medication group had a mean reduction in IOP of 5.32 mmHg more than the mean change in the placebo/no medication group (95% CI -7.37 to -3.28). Conjunctival blanching was an ocular adverse effect that was more common when brimonidine was given perioperatively compared with placebo in three studies.In our comparison of brimonidine versus apraclonidine, neither medication resulted in a lower risk of increased IOP of 5 mmHg or greater two hours of surgery; however, we were very uncertain about the estimate. There may be a greater mean decrease in IOP within two hours after LTP. We were unable to perform any meta-analyses for other review outcomes for this comparison.In our comparison of apraclonidine versus pilocarpine, we had insufficient data to perform meta-analyses to estimate effects on either of the primary outcomes. There was moderate-certainty evidence that neither medication was favored based on the mean change in IOP measurements from pre-LTP to two hours after surgery.In the comparison of medication given before LTP versus the same medication given after LTP, we had insufficient data for meta-analysis of IOP increase within two hours. For the risk of IOP increase of 5 mmHg or greater and 10 mmHg or greater at time points between two and 24 hours, there was no advantage of medication administration before or after LTP regarding the proportion of participants with an IOP spike (5 mmHg or greater: RR 0.82, 95% CI 0.25 to 2.63; 10 mmHg or greater: RR 1.55, 95% CI 0.19 to 12.43). For an IOP increase of 10 mmHg or greater, we had very low-certainty in the estimate, it would likely change with data from new studies.

AUTHORS' CONCLUSIONS

Perioperative medications are superior to no medication or placebo to prevent IOP spikes during the first two hours and up to 24 hours after LTP, but some medications can cause temporary conjunctival blanching, a short-term cosmetic effect. Overall, perioperative treatment was well tolerated and safe. Alpha-2 agonists are useful in helping to prevent IOP increases after LTP, but it is unclear whether one medication in this class of drugs is better than another. There was no notable difference between apraclonidine and pilocarpine in the outcomes we were able to assess. Future research should include participants who have been using these antiglaucoma medications for daily treatment of glaucoma before LTP was performed.