Baseline Factors Predictive of SLT Response: A Prospective Study

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.

Mechanism of selective laser trabeculoplasty: a systemic review

Although selective laser trabeculoplasty (SLT) is a recognized method for the treatment of glaucoma, the exact changes in the target tissue and mechanism for its intraocular pressure lowing effect are still unclear. The purpose of this review is to summarize the potential mechanisms of SLT on trabecular meshwork both in vivo and in vitro, so as to reveal the potential mechanism of SLT. SLT may induce immune or inflammatory response in trabecular meshwork (TM) induced by possible oxidative damage etc, and remodel extracellular matrix. It may also induce monocytes to aggregate in TM tissue, increase Schlemm's canal (SC) cell conductivity, disintegrate cell junction and promote permeability through autocrine and paracrine forms. This provides a theoretical basis for SLT treatment in glaucoma.

Selective laser trabeculoplasty: An updated narrative review

Selective laser trabeculoplasty (SLT) has experienced a resurgence in interest, primarily driven by promising findings from the Laser in Glaucoma and Ocular Hypertension Trial. By offering SLT as an initial drug-free treatment option, we may be able to thwart issues such as adherence and persistence that plague our current medical management protocols. In this comprehensive narrative review, we delve into the current body of literature that explores the utility of SLT across a wide spectrum of scenarios and glaucoma subtypes. We present evidence that provides valuable insight into the efficacy and benefits of SLT, positioning it as a viable option in the management of glaucoma. Careful consideration of the associated risks and challenges is also necessary for successful adoption into clinical practice. Despite the ample evidence supporting SLT's efficacy, some questions remain regarding its long-term effects and the potential need for retreatment. This review aims to shed light on these aspects to guide clinicians in making informed decisions and tailoring treatment plans to individual patient needs. This review also provides the readers with a bird's eye view of the potential impact of SLT and adds clarity to the various therapeutic protocols that one can follow to ensure optimal clinical outcomes for our patients.

Identifying Baseline Predictors of Selective Laser Trabeculoplasty Effectiveness: An Alternative Mathematical Approach

BACKGROUND

Selective laser trabeculoplasty (SLT) emerges as a first-line treatment for newly diagnosed open-angle glaucoma and ocular hypertension. However, the interindividual response to SLT considerably varied. Large-scale clinical investigations concerning predictive factors for SLT effectiveness are limited. This study aimed to identify baseline predictors of the percentage intraocular pressure (IOP)-lowering effectiveness of SLT using an alternative mathematical approach.

METHODS

Mathematical equations of IOP under the steady state of aqueous humour flow were formulated. The conclusive equation integrates physiological variables, including trabecular outflow facility, uveoscleral outflow fraction, plasma protein concentration, albumin/globulin ratio, mean arterial pressure, episcleral venous pressure, and plasma osmolarity. The equation was employed to estimate the percentage of IOP reduction following SLT and subsequently subjected to global sensitivity analysis to determine significant predictors of the IOP-lowering effect of SLT using the Monte Carlo simulation of 8,192 samples.

RESULTS

In the current model, a 50% improvement in the trabecular outflow facility impacted by SLT is associated with a mean percentage IOP reduction of 16.6%. Lower baseline trabecular outflow facilities were the strongest predictors, showing a correlation with greater effectiveness of SLT in terms of percentage of IOP reduction. The second most influential factor includes baseline uveoscleral outflow fraction, followed by baseline episcleral venous pressure. Specifically, lower baseline uveoscleral outflow fraction and episcleral venous pressure were found to be correlated with increased effectiveness of SLT. Baseline levels of plasma protein concentration, albumin/globulin ratio, mean arterial pressure, and plasma osmolarity have minimal impact on SLT success or failure.

CONCLUSION

This study identifies baseline trabecular outflow facilities as the strongest predictor of SLT effectiveness. The results suggested that pre-SLT medical treatment that augments uveoscleral outflow and/or trabecular outflow facilities could compromise the effectiveness of subsequent SLT in terms of percentage IOP reduction compared to those who never received pre-SLT medication.

[Factors affecting the hypotensive effect of selective laser trabeculoplasty in primary open-angle glaucoma]

PURPOSE

This study analyzes the influence of various factors on the hypotensive effect of selective laser trabeculoplasty (SLT) in patients with primary open-angle glaucoma (POAG).

MATERIAL AND METHODS

A retrospective study of the SLT effect was performed in 582 patients (756 eyes; mean age - 71.9±9.5 years) with POAG stages I-III. The level of intraocular pressure (IOP) decrease was assessed at 1 day, 1, 3, 6, and 12 months after SLT. The relationship between the hypotensive effect and age, gender, glaucoma stage, initial IOP level, number and type of instilled drugs, presence of intraocular lenses, and the surgeon performing the intervention were analyzed.

RESULTS

In the entire sample, the hypotensive effect of SLT after 1 day was 4.1±3.4 mm Hg, after 1, 3, 6, and 12 months - 3.7±4.8; 3.5±3.8; 3.1±3.4 and 2.3±3.8 mm Hg, respectively. The hypotensive effect of SLT was most dependent on the preoperative IOP level (R>0.64, p<0.05). No significant correlation was found between the hypotensive effect and the stage of POAG, gender, age, number of hypotensive drugs, phakia/aphakia, and the surgeon. A weaker hypotensive effect of SLT was found in eyes receiving monotherapy with α2-adrenoceptor agonists (p<0.03) and a combination of four drugs (p<0.02).

CONCLUSION

SLT is an effective method of additional IOP reduction in POAG at any stage and with any hypotensive regimen. At the same time, the results of its use in real clinical practice indicate the need for more careful IOP control after the procedure, especially in eyes with POAG stage III, as well as in eyes without hypotensive therapy and on the maximum drop regimen.

Selective Laser Trabeculoplasty

Selective laser trabeculoplasty (SLT) is a common ophthalmic procedure used to lower intraocular pressure. The mechanism of SLT action remains controversial but may involve the upregulation of protein expressions in the trabecular meshwork that increases outflow facility. Several prospective trials have demonstrated the safety and efficacy of SLT as both adjunctive and primary glaucoma therapy, and the utilization of SLT in stable, medically-controlled glaucoma patients may decrease medication burden and potentially improve the patients’ quality of life.

Outcomes of Selective Laser Trabeculoplasty After Prior Incisional Surgery for Open Angle Glaucoma

PRCIS

This retrospective case series of patients with open angle glaucoma and prior trabeculectomy or tube shunt surgery found that selective laser trabeculoplasty (SLT) resulted in significant intraocular pressure (IOP) reductions in the intermediate follow-up period in select cases.

PURPOSE

The purpose of this study was to assess the IOP-lowering effect and tolerability of SLT after prior trabeculectomy or tube shunt surgery.

MATERIALS AND METHODS

Open angle glaucoma patients at Wills Eye Hospital who previously underwent incisional glaucoma surgery and subsequently received SLT between 2013 and 2018 were included, along with an age-matched control group. Baseline characteristics, procedural data, and post-SLT data were recorded at 1, 3, 6, 12 months, and most recent visit. The primary success of SLT treatment was defined as IOP reduction of 20% or greater without the use of additional glaucoma medications compared to pre-SLT IOP. Secondary success was defined as IOP reduction ≥20% with the use of additional glaucoma medications compared to pre-SLT IOP.

RESULTS

There were 45 eyes in the study group and 45 eyes in the control group. In the study group, IOP decreased from a baseline of 19.5±4.7 mm Hg on 2.2±1.2 medications to 16.7±5.2 mm Hg ( P =0.002) on 2.2±1.1 glaucoma medications ( P =0.57). In the control group, IOP decreased from 19.5±4.2 mm Hg on 2.4±1.0 medications to 16.4±5.2 mm Hg ( P =0.003) on 2.1±1.3 medications ( P =0.36). There was no difference in IOP reduction or change in number of glaucoma medications after SLT at any postoperative visit between the 2 groups ( P ≥0.12 for all). Primary success rates at 12 months were 24.4% for the control group and 26.7% for the prior incisional glaucoma surgery group with no significant difference between the groups ( P =0.92). There were no persistent complications after SLT treatment in either group.

CONCLUSION

SLT may effectively lower IOP in patients with open angle glaucoma who have had previous incisional glaucoma surgery and should be considered in select cases.

Selective laser trabeculoplasty is safe and effective in patients previously treated with prostaglandin analogs: An evidence-based review

PURPOSE

Prostaglandin analogs (PGAs) are first-line treatments for ocular hypertension (OHT) and open-angle glaucoma (OAG). However, frequent side effects and high costs hinder patient's compliance resulting in disease progression. Evidence suggests selective laser trabeculoplasty (SLT) may be considered a first-line treatment for OHT and OAG due to its safety profile, minor side effects, and reduced costs. Considering that PGAs and SLT share action mechanisms, it is hypothesized that previous PGA therapy may affect subsequent SLT efficacy. Therefore, we analyzed if PGAs reduce SLT efficacy.

METHODS

An evidence-based review was performed to assess the safety and efficacy of SLT in patients previously treated with PGAs. For this purpose, we performed an extensive literature search using the National Library of Medicine's PubMed and Google Scholar database for all English language articles published until May 2021.

RESULTS

There is evidence of non-superiority of PGAs therapy versus SLT for OHT and OAG. A multicenter, randomized, observer-masked clinical trial (RCT) of untreated OHT and OAG patients concluded that SLT should be offered as the first-line treatment for these patients. This study was supported by a meta-analysis of RCTs, comparing SLT efficacy versus antiglaucoma drugs only, with the advantage of an SLT lower rate of adverse effects.

CONCLUSIONS

Cost-effectiveness, patient compliance, and antiglaucoma drugs' side effects, including higher surgical failure, favor consideration of SLT as first-line therapy for OAG and OHT. Furthermore, SLT efficacy does not seem to be affected by prior PGA administration; however, larger cohort, comparative, multicenter RCTs are necessary to answer this question.

Intraocular Pressure-Lowering Efficacy of a Sustained-Release Bimatoprost Implant in Dog Eyes Pretreated with Selective Laser Trabeculoplasty

Purpose: To assess the intraocular pressure (IOP)-lowering effect of a biodegradable bimatoprost implant following selective laser trabeculoplasty (SLT) in a canine model. Methods: Unilateral SLT was performed in 11 normotensive, treatment-naive beagle dogs. IOP was measured at baseline (pre-SLT) and weekly post-SLT (≤10 weeks). After IOP returned to baseline or at 10 weeks (whichever occurred first), a sustained-release bimatoprost implant was administered bilaterally in the anterior chamber of each animal. IOP was measured weekly for 4 weeks and then every 2 weeks up to week 42. Results: The main outcomes included the IOP change (%) from baseline, calculated in both eyes in the overall population, SLT responder subgroup (defined by peak IOP reduction from baseline ≥3 mmHg or ≥15% for >1 week post-SLT), and SLT nonresponder subgroup (defined by peak IOP reduction from baseline <3 mmHg or <15%). The bimatoprost implant lowered IOP similarly in both the SLT-treated and fellow SLT-naive eyes. Following bimatoprost implant administration, the mean (standard deviation [SD]) peak IOP reduction from baseline was 34.4% (8.5%) in SLT-treated eyes and 35.7% (5.9%) in fellow SLT-naive eyes. The bimatoprost implant lowered IOP comparably (P > 0.17) in eyes that responded to SLT (mean [SD] peak IOP reduction, 34.6% [10.7%]; n = 6) and those that did not (mean [SD] peak IOP reduction, 34.1% [6.1%]; n = 5). Conclusion: The bimatoprost implant effectively lowered IOP in eyes pretreated with SLT, regardless of response to SLT. The current data suggest that eyes previously treated with SLT can still benefit from the intracameral bimatoprost implant.

In Vivo Imaging of the Schlemm's Canal and the Response to Selective Laser Trabeculoplasty

OBJECTIVE

To evaluate the presence of angle dysgenesis on ASOCT (anterior segment optical coherence tomography) (ADoA) as a predictive factor in determining outcomes of selective laser trabeculoplasty (SLT).

DESIGN

A prospective clinical cohort study.

SUBJECTS

Patients with juvenile-onset open-angle glaucoma (JOAG) without angle dysgenesis on gonioscopy.

METHOD

JOAG patients with uncontrolled intraocular pressure (IOP), who were to undergo SLT, were evaluated for the presence or absence of ADoA, which was defined as the absence of Schlemm's canal (SC) and/or presence of a hyperreflective membrane (HM) over the trabecular meshwork, as identified on ASOCT before the SLT procedure. Furthermore, the number of ASOCT B-scans in which SC was identified as present, were then quantified. Success of SLT was defined as a reduction of IOP by 20% or more from pre-laser value at 6-month follow-up without any further IOP-lowering medication or surgery. Only 1 repeat SLT was admissible for defining SLT success over the 6-month period. A successful reduction in IOP at 6-month follow-up was correlated with the extent of ADoA.

RESULTS

In comparison to pre-SLT IOP, 57.1% eyes (20/35) showed more than 20% reduction in IOP at 6 months with a mean reduction of 7.6 ± 1.8 mm Hg (29.6%). When all 3 observers agreed, SC was identified in 90% eyes (18/20) with success vs 26.6% eyes (4/15) with failure (P < .001). All eyes (5/5) with presence of HM showed failure (P < .001). All eyes (19/19) in which SC was present in >50% ASOCT B scans (>25/50 scans/eye) showed success (P < .001). On a bias-reduced regression analysis, the identification of SC on any 2 consecutive scans increased the chances of success at 6 months by 8.3 times, whereas the identification of SC in >50% of ASOCT scans was associated with a 21.4 times greater chance of success.

CONCLUSIONS

The presence of SC on ASOCT is a strong predictor for successful IOP reduction after SLT in JOAG eyes.

Factors Associated With Favorable Laser Trabeculoplasty Response: IRIS Registry Analysis

PURPOSE

We examined patients in a large clinical registry to assess factors associated with laser trabeculoplasty (LTP) responses.

DESIGN

Retrospective cohort study.

METHODS

StudyPopulation: LTP patients in the Intelligent Research in Sight (IRIS) Registry, 2013-2018.

OBSERVATION

IRIS Registry data were extracted if the eye had a procedural code for LTP and a glaucoma diagnosis. Eyes were excluded if LTP laterality or baseline intraocular pressure (IOP) could not be determined. Following LTP, "nonresponders" were those with <20% IOP reduction after 8 weeks, while "responders" were those with ≥20% IOP reduction. MainOutcomeMeasures: Proportion of responders, odds ratios (OR) of pre-LTP factors associated with being a nonresponder.

RESULTS

A total of 263,480 eyes were included, with mean age 71.4 ± 11.7 years. Mean baseline IOP was 19.1 ± 5.0 mm Hg, mean number of pre-LTP medications was 2.1 ± 1.5. Response rate was 36.9% overall and 68.8% for those with baseline IOP >24 mm Hg. Higher baseline IOP was associated with reduced odds of nonresponse (OR = 0.60, P < .0001 for a 3 mm Hg increase). Angle recession, uveitis, and aphakia increased the odds of a nonresponse (ORs 2.46, 1.50 (both P < .0001), and 1.55 (P = .0259), respectively). In nonresponders with at least 1 medication at baseline, 76.3% of eyes had fewer medications postoperatively.

CONCLUSIONS

Lower baseline IOP, angle recession, uveitis, and aphakia were associated with increased odds of nonresponse. Future studies that analyze LTP responder survival and implementation lag would facilitate resource optimization in glaucoma therapy.

Outcomes of pattern scanning laser trabeculoplasty and selective laser trabeculoplasty: Results from the lausanne laser trabeculoplasty registry

PURPOSE

To compare the long-term safety and efficacy of pattern scanning laser trabeculoplasty (PSLT) and selective laser trabeculoplasty (SLT).

METHODS

This was a retrospective database analysis (Lausanne Laser Trabeculoplasty Registry) of patients having had laser trabeculoplasty (LT) prior to 2017 with a minimum follow-up of 1 year. Inclusion criteria were age ≥40 years and diagnosis of ocular hypertension (OHT) and open-angle glaucoma (OAG). Selective laser trabeculoplasty (SLT) eyes were matched to PSLT eyes according to baseline intraocular pressure (IOP), baseline number of ocular hypotensive medications (OHM) and glaucoma diagnosis. Success was defined as an IOP ≤ 20% from baseline or an IOP equal or lower than baseline accompanied by a reduction in OHM. Multivariate regression models were used to study associations between success and baseline clinical parameters.

RESULTS

From 280 eyes in the database, 81 eyes had PSLT and were matched with 81 SLT eyes (162 patients). Mean age was 69.4 ± 12.1 years, and 56.2% were female. Mean IOP was 18.6 ± 5.3 and 18.2 ± 4.1 mmHg at baseline and 15.9 ± 3.0 and 16.0 ± 3.4 mmHg at 12 months and 15.2 ± 2.7 and 16.2 ± 3.4 mmHg at 24 months, for PSLT and SLT, respectively. 60.5% of PSLT and 65.4% of SLT eyes achieved treatment success (p = 0.20). Number of OHM was 1.0 ± 1.0 and 1.4 ± 1.2, respectively (p = 0.052). Baseline IOP (OR = 1.23, p < 0.01) and number of OHM (OR = 1.67, p < 0.01) were associated with success in both PSLT and SLT, while LT modality was not [OR = 0.81 (0.43-1.53), p = 0.52], and a diagnosis of primary OAG was negatively associated (OR = 0.42, p = 0.04).

CONCLUSION

Our study did not find any significant differences between PSLT and SLT in terms of safety and efficacy in patients with OHT and glaucoma. Baseline IOP was associated with higher success rates in both procedures. Additional studies are needed to evaluate the outcomes of PSLT in non-Caucasian populations and the ability of repeat PSLT to achieve additional IOP reduction.

Predictive Factors for Outcomes of Selective Laser Trabeculoplasty

We sought to  determine predictive factors for selective laser trabeculoplasty (SLT) outcome. 252 eyes from 198 adult patients with open-angle glaucoma who underwent SLT between July 2016 and February 2018 with a minimum 6 month follow up were reviewed. We defined success as ≥20% IOP reduction or ≥1 medication reduction without an IOP lowering procedure. We also evaluated the relationship of these factors to postoperative IOP elevation >5 mmHg (IOP spikes). Our primary outcome measure was association between age, type and severity of glaucoma, pigmentation of the trabecular meshwork (PTM), total energy delivered, and baseline intraocular pressure (IOP) with success. At 2 and 6 months, 33.6% (76/226) and 38.5% (97/252) of eyes met success criteria respectively. Baseline IOP > 18 mmHg was significantly associated with success both at 2 and 6 months, reducing IOP by 5.4 ± 5.3 mmHg (23.7% reduction), whereas those with lower baseline remained at −0.7 ± 4.6 mmHg (4.9% increase) at 6 months (P < 0.001). No other baseline characteristics significantly predicted success or IOP spikes. Patients with higher baseline IOPs had greater success rates and mean IOP reduction at both 2 and 6 months following SLT. Age, type and severity of glaucoma, PTM, or total energy delivery had no association with procedural success or IOP spikes. Patients with higher baseline IOP may experience greater lowering of IOP after SLT. However, SLT may be equally successful for patients with a variety of other characteristics.

Non-contact direct selective laser trabeculoplasty: light propagation analysis

Selective laser trabeculoplasty (SLT), used to treat glaucoma and ocular hypertension, requires the use of a gonioscope placed on the cornea to visualize and irradiate the trabecular meshwork (TM). Alternatively, non-contact direct SLT (DSLT) irradiates the TM through the overlying tissues. Here we analyze this innovative procedure using analytical modeling and Monte Carlo simulations to quantify the laser energy reaching the TM through the overlying tissues. Compared with energy launched from the laser, DSLT energy transmission to the TM is 2.8 times less than SLT, which verifies the efficacy of non-contact DSLT given the lowest reported effective SLT energies.

Selective laser trabeculoplasty in exfoliative glaucoma eyes with prior argon laser trabeculoplasty

PURPOSE

To explore the efficacy of selective laser trabeculoplasty (SLT) within eyes with exfoliative glaucoma and history of prior argon laser trabeculoplasty (ALT).

METHODS

A single-centre trial consisting of 47 patients (47 eyes) with uncontrolled exfoliative glaucoma. The main outcome measure was intraocular pressure (IOP) reduction 3 and 9 months after SLT. Treatment success was defined as reduction from the preoperative IOP by 20% and 2 mmHg (<12 mmHg), 3 mmHg (12-16 mmHg) or 4 mmHg (>16 mmHg) depending on the baseline IOP.

RESULTS

Patient age was 79.3 ± 7.6 years (mean ± SD) and gender distribution 15 males and 32 females. The mean pre-SLT IOP was 15.6 ± 5.1 (range 9-28) mmHg, and mean number of glaucoma drugs 2.0 ± 1.2. The mean interval between prior ALT and SLT was 44.0 ± 36.9 (range 11-137) months. After SLT, the mean IOP change was -2.7 ± 4.2 mmHg (-14.8 ± 23.5%) at 3 months, and -2.8 ± 3.5 mmHg (-16.3 ± 19.4%) at 9 months. Pre-SLT IOP correlated with the IOP reduction at 3 months (r = 0.530, p < 0.001) and at 9 months (r = 0.432, p = 0.007). The overall success rate was 50% at 3 months, and 42% at 9 months. At both 3 and at 9 months, the cut-off level for treatment success was achieved when preoperative IOP was 18 mmHg and above. IOP lowering effect of SLT did not correlate with the number of glaucoma drugs, age, gender or use of prostaglandin inhibitors. Neither postoperative iritis nor other adverse effects were documented during the follow-up.

CONCLUSIONS

Selective laser trabeculoplasty is a safe and noteworthy treatment option to reduce IOP in exfoliative glaucoma eyes, especially with pre-SLT IOP over 18 mmHg.

Comparison of the effects of 180° and 360° applications of selective laser trabeculoplasty on intraocular pressure and cornea

PURPOSE

To compare the effects of 180° and 360° selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) and cornea in patients with bilateral primary open-angle glaucoma.

METHODS

Fifty-two eyes of 26 patients were included. On the same day, 180° SLT (Group 1) was applied to one eye of patients and 360° SLT (Group 2) to the other eye. IOP values were compared at pre-SLT and post-SLT 1 day, 1 week, 1, 3, and 6 months. Changes in central corneal thickness (CCT) and endothelial cell count (ECC) were examined.

RESULTS

In groups, significant decreases were observed in IOP at 1 week (p < 0.05), 1, 3, and 6 months (p < 0.001). No significant difference was determined between group 1 and 2 in IOP-lowering effectiveness or success rates (p > 0.05). There was no significant difference in CCT at inter- or intragroup comparisons (p > 0.05). In group 1, no significant difference was determined in pre- and post-SLT ECC (p > 0.05). In group 2, significant decrease in ECC was observed at 1 week (p < 0.05). However, ECC returned to its initial levels at 1 month.

CONCLUSIONS

To the best of our knowledge, this is the first study in literature to compare different quadrant SLT applications performed on both eyes, on the same day, in the same patient group and to compare the effects of those applications on IOP and cornea. In reducing IOP, 180° and 360° SLT are similarly effective. These effects begin on the 1st week and persist for 6 months. Temporary corneal changes may be observed following 360° SLT.

West Indies Glaucoma Laser Study (WIGLS)-2: Predictors of Selective Laser Trabeculoplasty Efficacy in Afro-Caribbeans With Glaucoma

PURPOSE

To identify factors associated with intraocular pressure (IOP) reduction following selective laser trabeculoplasty (SLT) in Afro-Caribbean people with primary open-angle glaucoma (POAG).

DESIGN

This was a prospective stepped-wedge study.

METHODS

Data were drawn from 72 Afro-Caribbean subjects with POAG participating in the ongoing West Indies Glaucoma Laser Study. Multivariable mixed-model analysis was utilized to develop a predictive model for percent IOP reduction 12 months following SLT. Putative factors (age, sex, site, baseline IOP, prior use of prostaglandin therapy, number of prewashout IOP-lowering medications, central corneal thickness, severity of glaucoma, duration of follow-up, and signs of acute postoperative inflammation) were evaluated in bivariate analysis. Factors significant at P≤0.2 were included in the final model. Right and left eye data were modeled separately.

RESULTS

At month 12 following SLT, mean IOP reductions in the West Indies Glaucoma Laser Study were 6.2 to 6.5 mm Hg (29.7% to 31.0%) in right and left eyes. The only factor significant in both eyes (P=0.0005 in right eyes and P<0.0001 in left eyes) was time, with IOP reductions being greatest at month 3 and declining slightly over time through month 12. Vertical cup-disc ratio (P=0.006) and prior prostaglandin therapy (P=0.004) were significant only in right eyes, and central corneal thickness (P=0.014) was significant only in left eyes. Factors significant only unilaterally did not approach significance in fellow eyes, suggesting the possibility that these represent type 1 errors. Site (St. Lucia vs. Dominica) was not a significant factor, establishing generalizability of these treatment outcomes to a broader population of African-derived people.

CONCLUSIONS

This analysis did not identify any subject-specific factors consistently predictive of therapeutic response to SLT. Of note, no factors predicted a suboptimal response. These findings favorably position SLT for broad application as primary therapy in African-derived people with POAG.

Predictors of Outcome in Selective Laser Trabeculoplasty: A Long-term Observation Study in Primary Angle-closure Glaucoma After Laser Peripheral Iridotomy Compared With Primary Open-angle Glaucoma

PURPOSE

To evaluate the efficacy of selective laser trabeculoplasty (SLT) for patients with primary angle-closure glaucoma (PACG) following a YAG laser peripheral iridotomy (PI) in comparison with primary open-angle glaucoma (POAG) and to assess the predictors of outcome of SLT.

PATIENTS AND METHODS

In retrospective study 68 patients with PACG after PI (68 eyes) and 74 POAG patients (74 eyes) were observed for 6 years. The effectiveness of SLT (20% reduction of intraocular pressure) was assessed using Kaplan-Meier survival analysis. The parameters for distinguishing the eyes with success and failure of SLT were detected by means of area under receiver operating characteristic curve (AUC). The predictive factors affecting SLT outcome were determined using Cox-regression analysis.

RESULTS

The success ratio was 87% in both groups in 1 year and dropped to 4% in PACG and to 6% in POAG in 6 years. Corneal hysteresis [odds ratio (ОR)=0.367, Р=0.005 for PACG, ОR=0.446, Р=0.008 for POAG] and age (OR=1.182, P=0.012 for PACG, OR=1.164, P=0.002 for POAG) were detected as the predictors of SLT outcome. In PACG pre-SLT anterior chamber depth was additional predictor (ОR=0.242, Р=0.001). The number of pre-SLT pressure-lowing medications was higher in the eyes with SLT failure (AUC, 0.794; P=0.0005 in PACG and AUC, 0.760; P=0.014 in POAG).

CONCLUSIONS

One-year efficacy of SLT in POAG and PACG after PI was high, but it was reduced in long-term period. Corneal hysteresis, age, and number of pre-SLT hypotensive eye drops were significant prognostic factors for treatment success in both glaucoma forms. In PACG pre-SLT anterior chamber depth affected the SLT outcome.

Comparison of successful outcome predictors for MicroPulse® laser trabeculoplasty and selective laser trabeculoplasty at 6 months

Purpose: To identify and compare factors predictive of successful outcome for MicroPulse^® laser trabeculoplasty (MLT) and selective laser trabeculoplasty (SLT).

Methods: 50 MLT-treated eyes and 50 SLT-treated eyes of open-angle glaucoma patients were reviewed for baseline characteristics, pre- and postoperative IOP and medications, and adverse events including postoperative IOP elevation >5 mmHg (IOP spikes) through 6 months of follow-up. Success was defined as ≥20% IOP reduction or ≥1 medication reduction without additional IOP lowering procedures at 6 months follow-up.

Results: MLT and SLT had similar success rates (44% vs 40%, P=0.983). Older age predicted success for SLT (P=0.013) but not MLT (P=0.154). Both MLT and SLT led to greater IOP lowering in patients with baseline IOP >18 mmHg, but only for SLT did baseline IOP have a significant association with success (P=0.035 vs P=0.983). Number of laser shots was associated with success in MLT (P=0.031) but not in SLT (P=0.970). Glaucoma severity and pigmentation of the trabecular meshwork (PTM) were not associated with rate of success for either group. The rate of IOP spikes was significantly (P=0.022) higher in the SLT group (10%) compared to none in the MLT group. No other complications or visually significant adverse events occurred in either group.

Conclusion: Although MLT and SLT resulted in similar success rates, older age and higher baseline IOP predicted success for SLT while MLT was equally efficacious regardless of these factors. Glaucoma severity and PTM were not associated with success of either laser procedures. 10% of SLT patients experienced IOP spike post procedure, whereas none in the MLT group did. MLT may be a safer alternative to SLT that is effective in lowering IOP and need for medications for a wider variety of patients with open angle glaucoma.

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SALT Trial: Steroids after Laser Trabeculoplasty: Impact of Short-Term Anti-inflammatory Treatment on Selective Laser Trabeculoplasty Efficacy

PURPOSE

This study examined whether short-term use of topical nonsteroidal anti-inflammatory drug (NSAID) or steroid therapy affected the efficacy of selective laser trabeculoplasty (SLT).

DESIGN

Double-masked, randomized, placebo-controlled, dual-center, multisurgeon trial.

PARTICIPANTS

Patients older than 18 years with intraocular pressure (IOP) of more than 18 mmHg for whom the clinician decided SLT was the appropriately indicated therapy were randomized to 1 of 3 groups in a ratio of 1:1:1 as follows: ketorolac 0.5%, prednisolone 1%, or saline tears.

METHODS

After SLT, patients randomized into each group were instructed to use an unmarked drop 4 times daily starting the day of SLT and continuing for 4 additional days. The Kruskal-Wallis test and Wilcoxon rank-sum test were used for continuous variables when comparing 2 or 3 treatment groups, respectively. The Fisher exact test was used for categorical variables.

MAIN OUTCOME MEASURES

The primary outcome of this study was IOP at 12 weeks. Secondary outcome measures included IOP at 1 and 6 weeks, patient-reported pain, and detectable anterior chamber inflammation.

RESULTS

Ninety-six eyes of 85 patients fit inclusion criteria and were enrolled between the 2 sites. The NSAID, steroid, and placebo groups were similar in baseline demographics and baseline IOP (mean, 23.3±3.9 mmHg; P = 0.57). There was no statistically significant difference in IOP decrease among groups at week 6. Both the NSAID and steroid groups showed a statistically significantly greater decrease in IOP at week 12 compared with the placebo group (mean, -6.2±3.1 mmHg, -5.2±2.7 mmHg, and -3±4.3 mmHg, respectively; P = 0.02 [analysis of variance] and P = 0.002 [t test] for NSAID vs. placebo groups; P = 0.02 for steroid vs. placebo groups).

CONCLUSIONS

Significantly better IOP reduction at 12 weeks was measured in eyes treated with steroid or NSAID drops after SLT. Short-term postoperative use of NSAID or steroid drops may improve IOP reduction after SLT. Longer-term follow-up studies are indicated.

Selective laser trabeculoplasty: past, present, and future

Over the past two decades, selective laser trabeculoplasty (SLT) has increasingly become an established laser treatment used to lower intraocular pressure in open-angle glaucoma and ocular hypertensive patients. In this review we trace the origins of SLT from previous argon laser trabeculoplasty and review the current role it has in clinical practice. We outline future directions of SLT research and introduce emerging technologies that are further developing this intervention in the treatment paradigm of glaucoma.

Preoperative intraocular pressure as a predictor of selective laser trabeculoplasty efficacy

PURPOSE

To identify predictors of intraocular pressure (IOP) reduction following selective laser trabeculoplasty (SLT) in patients with high- and low-pressure primary open-angle glaucoma, who are already taking maximally tolerated IOP-lowering medication and need further IOP reduction.

METHODS

In this prospective interventional case series, 157 eyes of 157 open-angle glaucoma patients who were assigned for SLT for further IOP reduction were included. Each patient had diurnal IOP measurements taken before and on average 6 months following SLT. The mean of six IOP measurements was compared. The following parameters were analysed for their association with SLT success: age, gender, spherical equivalent, high-pressure or normal-pressure open-angle glaucoma, number and type of pressure-lowering medications, lens status, pre-SLT IOP, IOP at the time of diagnosis, duration of glaucoma, visual field stage and central corneal thickness.

RESULTS

The only parameter that was predictive for absolute and relative mean diurnal IOP reduction after SLT was the preoperative mean diurnal IOP. One hundred per cent of the patients with a mean diurnal preoperative IOP of more than 18 mmHg had an IOP reduction after SLT. With mean diurnal preoperative values of 14-18 mmHg, 83.1% of the patients, and with values below 14 mmHg only 64% of the patients, showed an IOP reduction. This difference was statistically significant (>18 compared to 14-18: p = 0.002; >18 compared to <14: p = 0.001; 14-18 compared to <14: p = 0.030).

CONCLUSIONS

The pressure-lowering effect of SLT can best be predicted by the individual IOP level before treatment. Patients with mean diurnal IOP levels below 14 mmHg might not benefit from the procedure at all.

Selective Laser Trabeculoplasty in Primary Angle-closure Glaucoma After Laser Peripheral Iridotomy: A Case-Control Study

PURPOSE

To evaluate the outcomes of selective laser trabeculoplasty (SLT) in patients with primary angle closure (PAC/PACG) following a YAG peripheral laser iridotomy (PI) compared with primary open-angle glaucoma (POAG).

METHODS

A case-control study compared the effectiveness of SLT in PAC/PACG to POAG. Data from patients who underwent SLT after a successful PI for PAC/PACG (PAC/PACG group) with an opening of the angle for at least 180 degrees were compared with a POAG group that was randomly matched to the PAC/PACG group for age, baseline intraocular pressure (IOP), and severity of glaucoma. Data were collected on the change in IOP from baseline and reduction in number of medications following SLT in both groups. SLT was considered successful when IOP decreased by ≥20% of the baseline IOP without further medical or surgical intervention or a reduction in glaucoma medications by ≥1 from the baseline number while maintaining the target IOP.

RESULTS

In the PAC/PACG group, 59 eyes with persistent IOP elevation after successful PI underwent SLT in areas where the angle was open for at least 180 degrees; 41% (n=24) of PAC/PACG had scattered peripheral anterior synechiae (PAS) of ≤180 degrees. In the POAG group, 59 eyes underwent SLT. Fifty-nine percent in the PAC/PACG group and 85% in POAG group had 360-degree treatment, with 74 and 78 shots at 0.53 and 0.62 mJ per laser application, respectively. In the PAC/PACG group, IOP was 19.3±6.5 mm Hg at baseline and 15±3.5 mm Hg10 months after SLT, and the number of medications decreased from 2.3 at baseline to 1.4 at 10 months postoperatively. In the POAG group, IOP was 19.6±5.6 mm Hg at baseline, and 16.1±3.7 mm Hg 11 months after SLT and the glaucoma medications decreased from 2.3 to 1.1. The postoperative IOP reduction in the PAC/PACG and POAG was not significantly different (P=0.66). The success rate of achieving clinically significant IOP reduction of 20% or more from baseline, or discontinuation of one or more of glaucoma medications was 84.7% in the PAC/PACG group and 79.6% in the POAG group (P=0.47). An IOP spike occurred in 10% (n=6) in PACG/PAC and 5% (n=3) in POAG and was controlled with topical medications (P=0.49).

CONCLUSION

The safety and efficacy of SLT was equivalent in PAC/PACG and POAG.

The effect of repeat 360-degree selective laser trabeculoplasty on intraocular pressure control in open-angle glaucoma

OBJECTIVE

To evaluate the effect of repeat 360-degree selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) with short-term follow-up.

METHODS

This study was based on clinical practice (25 females and 13 males) with a history of primary open-angle glaucoma (27), normotensive glaucoma (6) or pseudoexfoliative glaucoma (5). We measured the IOP at baseline before the first and second 360-degree SLT at 1 month, 6 months and 15 months. Follow-up was concluded earlier if the SLT failed (an increase in IOP over the baseline value), if a new medication was introduced or if an IOP lowering surgery was performed.

RESULTS

Baseline IOP prior to SLT1 was 19.0 ± 3.7 mmHg, which dropped to 16.0 ± 3.7 mmHg (17.0% reduction), 16.9 ± 3.8 mmHg (12.5% reduction) and 17.2 ± 3.3 mmHg (8.7% reduction) at 1, 6 and 15 months respectively (P<0.01). For SLT2, baseline IOP was 18.0 ± 4.5 mmHg, which dropped to 15.1 ± 3.8 mmHg (15.1% reduction), 15.1 ± 4.3 mmHg (15.6% reduction) and 16.0 ± 3.6 mmHg (10.3% reduction) at 1, 6 and 15 months respectively (P<0.01).

CONCLUSION

In a cohort of patients who underwent 360-degree SLT 4 years previously, a second SLT resulted in IOP lowering similar to the first treatment with a possibly more sustained response.

Long-term outcomes in patients initially responsive to selective laser trabeculoplasty

AIM

To determine the long-term effects of selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) and the number of medications used up to 5y following treatment in glaucoma patients receiving maximally tolerated medical therapy (MTMT).

METHODS

The Wills Eye Hospital Glaucoma Research Center retrospectively reviewed the charts of glaucoma patients who underwent SLT after receiving MTMT. Eyes that did not achieve their target pressure within 3mo following SLT were excluded from the study. Changes in mean IOP and number of glaucoma medications used were analyzed at 1, 3, and 5y following SLT.

RESULTS

Seventy-five eyes of 67 patients were included in the study. Fifteen eyes that received SLT failed to achieve their target pressure within 3mo and were excluded from the study. The average follow-up time was 37.4mo (±14.4). Mean IOP was significantly reduced 1y after treatment (P=0.005). It was also reduced 3, 5y after treatment without reaching statistical significance (P=0.20 and P=0.072, respectively). There was a significant decrease in mean number of medications used 1, 3, 5y after treatment (P<0.001, P<0.001, and P=0.039, respectively). In the span of 5y, 2 eyes (2.7%) underwent repeat SLT, 7 eyes (9.3%) underwent glaucoma surgery and an additional 3 eyes (4.0%) underwent both.

CONCLUSION

SLT significantly reduced the number of glaucoma medications used 5y following treatment in glaucoma patients receiving MTMT. SLT may delay operating-room surgery.

Selective laser trabeculoplasty (SLT): 1-year results in early and advanced open angle glaucoma

The purpose of this study was to examine the efficacy of selective laser trabeculoplasty (SLT) in eyes with early and more advanced stages of open angle glaucoma within 1 year of follow-up. Retrospective chart review in a consecutive series of patients treated by SLT to reduce intraocular pressure (IOP) or decrease number of topical medications in cases of discomfort and allergy. The cup-to-disc ratio of the optic nerve and the GSS 2 (glaucoma staging system 2) was used to differentiate between early (group 1) and more advanced (group 2) stages of glaucoma. At the time of SLT treatment, no new signs of glaucoma progression were seen. Only the first treated eye of every patient was included in the analysis. In group 1 (early glaucoma), 27 eyes were included. IOP reduction <21 mmHg/>20 % of the preoperative IOP-value and reduction of medication were achieved in 17 eyes (62.96 %). Successful re-treatment was necessary in 2 eyes (7.4 %). In group 2 (advanced glaucoma), 44 eyes underwent SLT. In eight eyes (18.18 %), filtrating surgery was necessary after initial SLT. In the remaining 36 eyes, IOP reduction <21 mmHg/>20 % of the baseline IOP was achieved in 26 eyes (59.09 % of 44 eyes) and IOP reduction <18 mmHg/> 30 % of the baseline IOP in 22 eyes (50 % of 44 eyes). SLT was safe and effective in nearly 2/3 of early glaucoma patients and also in 50 % of advanced glaucoma patients using stronger criteria of success. Failure of SLT in advanced glaucoma should lead to immediate filtrating surgery, which seems not to be associated with higher risk of fibrosis.

Predictors of success in selective laser trabeculoplasty for primary open angle glaucoma in Chinese

Purpose

To determine the predictors of success for adjuvant selective laser trabeculoplasty (SLT) in Chinese primary open angle glaucoma (POAG) patients.

Methods

This prospective study recruited Chinese subjects with unilateral or bilateral POAG currently taking medication to reduce intraocular pressure (IOP). All subjects received a single session of 360° SLT treatment and continued their medications for 1 month. SLT success was defined as IOP reduction ≥20% at 1 month. The following covariates were analyzed in both groups via univariate and multivariate analyses: age, sex, lens status, initial IOPs, post-SLT IOPs, number and type of medications, SLT shots and energy, and pre-SLT investigations.

Results

In 51 eyes of 33 POAG subjects, the success rate of SLT was 47.1%. Certain groups of patients were associated with greater success using univariate analysis. These groups included the following: older age (coefficient =0.1; OR: 1.1; P=0.0003), a higher pre-SLT IOP (coefficient =0.3; OR: 1.3; P=0.0005), using four types of antiglaucoma medication (coefficient =2.1; OR: 8.4; P=0.005), a greater degree of spherical equivalent (coefficient =2.1; OR: 8.4; P=0.005), and the use of a topical carbonic anhydrase inhibitor (coefficient =1.7; OR: 6.0; P=0.003). None of the covariates were significant using multivariate analysis.

Conclusion

Older age, a higher pretreatment IOP, using multiple antiglaucoma medications especially topical carbonic anhydrase inhibitor, and higher refractive errors were associated with greater SLT success.

[Selective laser trabeculoplasty: results after a first and a second session, overall comparison and results for three indications]

PURPOSE

To compare the results obtained with SLT trabeculoplasty after an initial treatment (SLT-1) and after a second treatment (SLT-2). Subgroup analysis according to trabecular pigmentation and the existence of a high myopia.

MATERIALS AND METHODS

Retrospective study of 77 patients, 152 SLT sessions performed in the Ophthalmology Department of Clermont-Ferrand University Medical Center, 118 SLT-1, 34 SLT-2. Three comparable groups of patients were assembled: group 1 (glaucoma patients with normal or subnormal trabecular pigmentation), group 2 (glaucoma patients with high myopia), and group 3 (glaucoma patients with significant trabecular pigmentation). The results were compared between groups, for SLT-1 and SLT-2.

RESULTS

Intraocular pressure lowering was consistent with data reported in the literature. Comparison of the results of SLT-1 versus SLT-2 did not find any significant difference in terms of IOP change. However, after SLT-2, the IOP response appears significantly greater (P=0.03) in the group with significant trabecular pigmentation compared to the non-myopic group with normal trabecular pigmentation.

DISCUSSION

Our results are consistent with the literature for efficacy, tolerance and reproducibility of SLT. No reduction in SLT efficacy was observed after a second session. Trabecular pigmentation is not a predictor of the response after the first session. In the case of retreatment (SLT-2), the differences observed lead to the hypothesis that it may be appropriate to perform at least two SLT treatments in patients with significant trabecular pigmentation in order to obtain maximal effect. Myopia, a variable not previously studied, does not seem to influence SLT outcomes.

CONCLUSION

Trabecular pigmentation and the presence of myopia do not appear to be predictive of a successful first treatment. However, our study leads us to suggest the hypothesis that the maximal response of SLT in patients with significant trabecular pigmentation is not obtained until after at least two sessions. This observation opens an interesting perspective on the therapeutic strategy to adopt in the case of pigmentary glaucoma.

Surgical Decisions in Primary Open Angle Glaucoma with Low or Normal Tension

Glaucoma, given its insidious nature, is often coined 'the sneak thief of sight'. Following this trail of thought, primary open angle glaucoma with low or normal tension (POAGLNT) could be coined 'the king of thieves'. The lack of a compelling red fag of high intraocular pressure (IOP), together with the diurnal fuctuation of the deceptively low baseline IOP, POAGLNT poses a therapeutic challenge in terms of judging when to intervene, and how. In this review article, we will outline the considerations before undergoing surgery: risk stratification, defining goal in terms of target pressure and IOP modulation. We will also review the strengths, weaknesses and pearls of available options. How to cite this article: Shum JW, Leung DY. Surgical Decisions in Primary Open Angle Glaucoma with Low or Normal Tension. J Current Glau Prac 2013;7(3):121-127.

Selective Laser Trabeculoplasty: A Clinical Review

Selective laser trabeculoplasty (SLT) is a safe and effective treatment modality for lowering the intraocular pressure in patients with glaucoma. It achieves its results by selective absorption of energy in the trabecular pigmented cells, sparing adjacent cells and tissues from thermal damage, with minimal morphological tissue alteration following treatment. On the basis of the peer-reviewed medical literature, SLT is efficacious in lowering IOP, as initial treatment or when medical therapy is insufficient in all types of open-angle glaucoma in all races. SLT achieves intraocular pressure reduction similar to that of argon laser trabeculoplasty but without the tissue destruction and side effects. Observed side effects following SLT were almost uniformly transient and minor. We review highlights of recently published studies on the mechanisms and clinical outcome of SLT in order to address frequently raised issues pertinent to SLT in the clinical practice.

KEY MESSAGES

Selective laser trabeculoplasty is a safe and effective treatment modality for lowering the intraocular pressure in patients with glaucoma. How to cite this article: Alon S. Selective Laser Trabeculoplasty: A Clinical Review. J Current Glau Prac 2013; 7(2):58-65.