Mechanisms of selective laser trabeculoplasty: a review

Interventional glaucoma: Rethinking glaucoma treatment paradigms in the Asian context

The emergence and advancements in glaucoma treatment modalities have expanded the options available to clinicians, particularly for patients with mild to moderate glaucoma. These newer approaches, such as minimally invasive glaucoma surgeries and selective laser trabeculoplasty, aim to effectively reduce intraocular pressure and potentially improve patient outcomes. 'Interventional glaucoma' reflects a paradigm shift in the glaucoma management strategies and involves adopting a more proactive approach and offering these interventions at earlier stages of the disease. By administering them earlier, these interventions can modulate the course of the disease and prevent significant visual loss, thereby reducing or delaying the need for subsequent filtering surgeries. In this review, we discuss the need for interventional glaucoma and the evidence behind these interventional techniques. We highlight key considerations that should be considered when implementing interventional glaucoma approaches in the Asian context.

Schlemm's canal-selective Tie2/TEK knockdown induces sustained ocular hypertension in adult mice

Deficient Angiopoietin-Tie2 signaling is linked to ocular hypertension in glaucoma. Receptor Tie2/TEK expression and signaling at Schlemm's canal (SC) is indispensable for canal integrity and homeostatic regulation of aqueous humor outflow (AHO) and intraocular pressure (IOP), as validated by conditional deletion of Tie2, its ligands (Angpt1, Angpt2 and Angpt3/4) or regulators (Tie1 and PTPRB/VE-PTP). However, these Tie2/TEK knockouts and conditional knockouts are global or endothelial, preventing separation of systemic and ocular vascular defects that impact retinal or renal integrity. To develop a more targeted model of ocular hypertension induced by selective knockdown of Tie2/TEK expressed in SC, we combined the use of viral vectors to target the canal, and two distinct gene-editing strategies to disrupt the Tie2 gene. Adeno-associated virus (AAV2) is known to transduce rodent SC when delivered into the anterior chamber by intracameral injection. First, delivery of Cre recombinase via AAV2.Cre into R26tdTomato/+ reporter mice confirmed preferential and stable transduction in SC endothelium. Next, to disrupt Tie2 expression in SC, we injected AAV2.Cre into homozygous floxed Tie2 (Tie2FL/FL) mice. This led to attenuated Tie2 protein expression along the SC inner wall, decreased SC area and reduced trabecular meshwork (TM) cellularity. Functionally, IOP was significantly and steadily elevated, whereas AHO facility was reduced. In contrast, hemizygous Tie2FL/+ mice responded to AAV2.Cre with inconsistent and low IOP elevation, corroborating the dose-dependency of ocular hypertension on Tie2 expression/activation. In a second model using CRISPR/SaCas9 genome editing, wild-type C57BL/6 J mice injected with AAV2.saCas9-sgTie2 showed similar selective SC transduction and comparable IOP elevation in course and magnitude to that induced by AAV2.Cre in Tie2FL/FL mice. Together, our findings, demonstrate that selective Tie2 knockdown in SC is a targeted strategy that reliably induces chronic ocular hypertension and reproduces glaucomatous damage to the conventional outflow pathway, providing novel models of SC-Tie2 signaling loss valuable for preclinical studies.

Comparative outcomes of selective laser trabeculoplasty delivered by optometrists compared with ophthalmologists: a UK-based multicentre observational study

BACKGROUND

Selective laser trabeculoplasty (SLT), a National Institute for Care and Health Excellence recommended first-line treatment for open-angle glaucoma and ocular hypertension, is increasingly delivered by optometrists. This retrospective multicentre observational study evaluates real-world outcomes of SLT comparing optometrist-treated to ophthalmologist-treated eyes.

METHODS

Adults aged ≥40 years receiving first SLT treatment at three UK hospital eye units (Aintree, Manchester, Macclesfield) between 1 August 2018 and 1 August 2021 were analysed using anonymised local audit data. Outcomes included intraocular pressure (IOP), visual acuity (VA), drop burden, complications including post-SLT IOP spikes, and composite treatment failures including repeat laser or glaucoma surgery, evaluated at 6-monthly intervals up to 24 months. Groups were compared with parametric and non-parametric tests, accounting for intereye correlation, and Kaplan-Meier survival analysis using composite treatment failure endpoints was conducted.

RESULTS

207 eyes (131 patients) were analysed, 84 (56 patients) optometrist-treated eyes compared with 123 ophthalmologist-treated eyes (75 patients). No statistically significant differences (p>0.05) were found in change in VA, IOP or glaucoma drops from pre-SLT baseline between optometrist and ophthalmologist-treated eyes, at all time points. More cataracts were detected in optometrist-treated eyes, however, this did not affect differences in VA or cataract surgery frequency. More optometrist-treated eyes underwent glaucoma surgery, however, ophthalmologist-treated eyes had higher drop burden and chance of composite treatment failure up to month 18.

CONCLUSION

Outcomes of SLT treatment by optometrists and ophthalmologists are comparable up to 24 months post-treatment. Ophthalmologist-treated eyes may have had more aggressive eye-drop treatment, preventing the need for surgery.

Intraocular Pressure Response in the Untreated Contralateral Eye After Selective Laser Trabeculoplasty

AIM

To examine the impact of selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) in the untreated contralateral eye within 12 months after the procedure.

METHODS

A retrospective chart review was conducted on patients with primary open-angle, normal-tension, pigmentary, or pseudoexfoliation glaucoma who received 360-degree SLT at George Washington University. Exclusion criteria included prior or subsequent laser or glaucoma surgery within 12 months of SLT, other glaucoma types, or corticosteroid use during follow-up. Primary outcomes were IOP and medication reduction, and SLT success, defined as reducing IOP by ≥20% without additional IOP-lowering procedures or medications. Follow-up occurred at six weeks, six months, and 12 months. Demographic and clinical data were analyzed using ANOVA, paired t-tests, and chi-squared tests.

RESULTS

A total of 125 patients were included, representing a range of backgrounds: African American (57.6%), Caucasian (31.2%), Asian (5.6%), and Hispanic/Latino (4%), and 1.6% did not report their background. Significant reductions in mean IOP and medication numbers were observed in the contralateral eye at six weeks and six months (p<0.05) but not at 12 months. The contralateral eye success rates were 24% at six weeks and six months and 20.8% at 12 months. The contralateral eye was more likely to achieve success if the ipsilateral eye was successful at six weeks (odds ratio (95% confidence interval): 5.05 (1.89-13.48)), six months (16.1 (4.56-57.17)), and 12 months (5.94 (2.07-17.04)) (p<0.001 for all).

CONCLUSION

First-time SLT results in statistically significant IOP and medication reductions in the contralateral eye at six weeks and six months. The contralateral eye was 5.05-16.1 times more likely to achieve success if the ipsilateral eye was successful within 12 months.

Real-world results of the Zeiss selective laser trabeculoplasty in adult South African primary open-angle glaucoma patients

Background

Selective laser trabeculoplasty (SLT) is an effective long-term option for the treatment of open-angle glaucoma.

Objectives

To investigate the real-world efficacy and safety of SLT with the Zeiss VISULAS green laser in medically treated primary open-angle glaucoma (POAG).

Design

Retrospective, single-center study.

Methods

POAG patients ⩾18 years of age on at least one antiglaucoma medication prior to the procedure, who underwent SLT with the Zeiss VISULAS green laser (Carl Zeiss Meditec, Jena, Germany). Medications were terminated or reinstated at subsequent follow-ups depending on the intraocular pressure (IOP) control. The primary efficacy outcome measures were mean reduction in glaucoma medications and mean reduction in IOP at 3, 6, and 12 months compared to baseline. Safety outcomes were intra- or post-procedural complications.

Results

One hundred fifty-six eyes of 156 patients, aged 66.5 ± 13.2 years, were recruited. The mean number of medications was reduced from 2.3 ± 1.0 at baseline to 0.8 ± 1.1 and 0.8 ± 1.2 at 3- and 6 months, respectively (p < 0.001). Despite the reduction of medications, the mean IOP (mmHg) was reduced from 16.6 ± 3.10 at baseline to 15.4 ± 3.82 at 3 months (n = 156) and 15.1 ± 3.30 at 6 months (n = 140) (p < 0.001). IOP reduction ⩾20% was observed in 28.8% of patients at 3 months and 27.9% of patients at 6 months. In the 12-month follow-up group (n = 22), mean medications and IOP (mmHg) at baseline were 2.3 ± 0.9 and 16.0 ± 2.80, respectively, which decreased to 0.9 ± 1.1 (p < 0.001) and 14.5 ± 1.92 (p = 0.103), respectively. At 3- and 6-month post-procedure, 59.6% of patients and 60% of patients, respectively, were medication-free compared to none at baseline. At 6 months, 69.3% of patients maintained IOP lower than or equal to pre-procedure IOP on fewer medications compared to baseline. No vision-threatening intra- or post-procedure complications were noted.

Conclusion

SLT with the Zeiss VISULAS green laser resulted in a clinically and statistically significant reduction in number of medications needed for IOP control. The procedure had a good safety profile similar to that described in the literature for SLT, with no vision-threatening complications.

Glaucoma: now and beyond

The glaucomas are a group of conditions leading to irreversible sight loss and characterised by progressive loss of retinal ganglion cells. Although not always elevated, intraocular pressure is the only modifiable risk factor demonstrated by large clinical trials. It remains the leading cause of irreversible blindness, but timely treatment to lower intraocular pressure is effective at slowing the rate of vision loss from glaucoma. Methods for lowering intraocular pressure include laser treatments, topical medications, and surgery. Although modern surgical innovations aim to be less invasive, many have been introduced with little supporting evidence from randomised controlled trials. Many cases remain undiagnosed until the advanced stages of disease due to the limitations of screening and poor access to opportunistic case finding. Future research aims to generate evidence for intraocular pressure-independent neuroprotective treatments, personalised treatment through genetic risk profiling, and exploration of potential advanced cellular and gene therapies.

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.

The impact of topical NSAID treatment on selective laser trabeculoplasty efficacy

PURPOSE

Selective laser trabeculoplasty (SLT) is a first-line intervention for glaucoma, with the aim to reduce the intraocular pressure (IOP). Topical non-steroidal anti-inflammatory drugs (NSAIDs) are sometimes prescribed after SLT. However, it has been proposed that such treatment may either increase or reduce SLT efficacy. The purpose of this study was to investigate this further.

METHODS

The study was a retrospective chart review, including 192 eyes of 192 patients, half of which received a course of NSAID eyedrops after SLT. Absolute and relative IOP reduction 3-12 weeks after SLT was compared. Furthermore, subgroup analyses, a multiple linear regression analysis, and a Kaplan-Meier survival analysis regarding time to treatment escalation were performed.

RESULTS

The mean absolute IOP reduction was 4.3 ± 3.4 mmHg in the NSAID group and 5.4 ± 4.1 mmHg in the control group (p = 0.049). Relative IOP reduction was 17.5% ± 13.0% and 21.8% ± 14.8% in the NSAID and control groups, respectively (p = 0.033). The same tendency of superior results in control eyes compared with NSAID eyes was seen in an extensive subgroup analysis. A multiple linear regression analysis confirmed NSAID treatment as a negative predictor of IOP reduction after adjustment for covariates (p = 0.023). Survival analysis showed a longer median time to treatment escalation in the control group, though not statistically significant.

CONCLUSION

Topical NSAID treatment was not associated with an increased SLT efficacy. On the contrary, the present study is the first to demonstrate that SLT effectiveness may even be reduced by NSAIDs.

Energy Dose-Response in Selective Laser Trabeculoplasty: A Review

PRCIS

A literature review of selective laser trabeculoplasty (SLT) energy dose-response found no definitive relationship between intraocular pressure (IOP) reduction with respect to total or pulse energy, race, pigmentation, or application pattern.

PURPOSE

SLT is a safe and effective treatment for lowering IOP. Although evidence is mounting for the advantage of its use as a first-line treatment for IOP reduction, the SLT procedures in use vary widely. The purpose of this literature review was to investigate whether there were any relationships between SLT energy and efficacy for lowering IOP in the published literature.

METHODS

A literature review was undertaken that included studies in which energy levels required for successful SLT treatment were investigated: in general, with respect to angle pigmentation, race or ethnicity, and treatment arc extent.

RESULTS

There was no indication that higher (or lower) energy used in the treatment leads to greater (or less) IOP reduction. Similar results were obtained regarding the level of trabecular meshwork pigmentation. Race was not found to be associated with altered dose response in SLT. There were indications that treating the full 360 degrees, as opposed to smaller arcs, could be beneficial for more IOP reduction. IOP reduction from SLT was found to be similar to that provided by topical medications.

CONCLUSIONS

The optimal energy level of SLT needed for IOP reduction has not yet been definitively established, with all reported pulse energies resulting in similar IOP reduction. Furthermore, similar lack of conclusive findings exists regarding optimal SLT energy dosage for use in different races and degrees of trabecular meshwork pigmentation. This parameter and each of the abovementioned factors requires further research.

A Review of Selective Laser Trabeculoplasty: "The Hype Is Real"

Presently, there is no efficacious treatment for glaucomatous optic neuropathy; the current treatment is focused on lowering intraocular pressure (IOP). Studies have demonstrated the safety and efficacy of selective laser trabeculoplasty (SLT) in reducing the IOP in eyes with open-angle (OAG) glaucoma or ocular hypertension (OH). Moreover, the European Glaucoma Society has instated SLT as the first-line or adjunctive treatment in OAG or OH, reiterating its clinical significance. In this review, we outline the old and the new roles of SLT, with an emphasis on clinical practice, and look further into its renewed appeal and future developments.

Effect of pigmentation intensity of trabecular meshwork cells on mechanisms of micropulse laser trabeculoplasty

The intraocular pressure (IOP)-lowering mechanisms of micropulse laser trabeculoplasty (MLT) remain unclear. The present study was performed to investigate the mechanism of action of MLT, and to determine whether the pigmentation intensity of trabecular meshwork (TM) cells is associated with the treatment effects. Primary human TM cells were exposed to melanin granules to artificially introduce different levels of pigmentation. Micropulse (MP) laser irradiation was performed, and interleukin (IL)-1α/β, matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), and extracellular matrix (ECM) protein expression were evaluated by RT-qPCR and immunocytochemistry. IL-1α/β and MMP-1, -3, and -9 mRNA expression were significantly upregulated at 4 and 24 h after MP laser irradiation, respectively, but there were no significant changes in TIMP expression. The extent of these upregulation was greater in cells with strong pigmentation intensity. Protein expressions of fibronectin and collagen I were significantly decreased in cells with strong staining intensity. These results suggested that MP laser irradiation alter the MMP/TIMP ratio and enhance ECM turnover, resulting in increased outflow of aqueous humor. The pigmentation intensity of the TM tissues may affect the treatment efficacy of MLT, because TM cells with strong staining intensity showed a significantly enhanced response to MP laser irradiation.

Morphological changes to Schlemm's canal and the distal aqueous outflow pathway in monkey eyes with laser-induced ocular hypertension

Though roughly 30-50% of aqueous outflow resistance resides distal to Schlemm's canal (SC), the morphology of the conventional outflow pathway distal to SC has not been thoroughly evaluated. This study examined the morphological changes along proximal and distal aspects of the conventional aqueous outflow pathway and their association with decreased outflow facility in an experimental model of glaucoma in cynomolgus macaques. Nd:YAG laser burns were made to 270-340 degrees of the trabecular meshwork (TM) of one eye (n = 6) or both eyes (n = 2) of each monkey to induce ocular hypertension. Distinct regions of the TM were left unlasered. Contralateral eyes (n = 5) were not lasered and were utilized as controls. Monkeys were sacrificed ≥58 months after their last laser treatment. All eyes were enucleated and perfused at 15 mmHg for 30 min to measure outflow facility. Two pairs of eyes were also perfused with fluorescein to examine segmental outflow. All eyes underwent perfusion-fixation for 1 h. Anterior segments were cut into radial wedges and processed for light and electron microscopy. Width, height, and cross-sectional area (CSA) of SC were compared between high- and low-flow regions of control eyes, and between non-lasered regions of laser-treated eyes and control eyes. Number and CSA of intrascleral veins (ISVs) were compared between non-lasered and lasered regions of laser-treated eyes and control eyes, and between high- and low-flow regions of control eyes. Scleral collagen fibril diameter was compared between control eyes and lasered and non-lasered regions of laser-treated eyes. Median outflow facility was significantly decreased in laser-treated eyes compared to control eyes (P = 0.02). Median CSA and height of SC were smaller in high-flow regions than low-flow regions of control eyes (P < 0.05). Median width of SC was not significantly different between high- and low-flow regions of control eyes (P > 0.05). Median CSA, width, and height of SC were not different between non-lasered regions and control eyes (P > 0.05). SC was partially or completely obliterated in lasered regions. Median number of ISVs was significantly decreased in lasered regions compared to non-lasered regions (P < 0.01) and control eyes (P < 0.01). Median CSA of ISVs did not differ between these groups (P > 0.05). Median number and CSA of ISVs were not significantly different between high- and low-flow regions of control eyes (P > 0.05). Lasered regions displayed looser scleral stroma and smaller median diameter of collagen fibrils adjacent to the TM compared to non-lasered regions (P < 0.05) and control eyes (P < 0.05). Dense TM, partial to complete obliteration of SC, and a decreased number of patent ISVs may account in part for the decreased outflow facility in monkey eyes with laser-induced ocular hypertension. The significance of changes in scleral structure in laser-treated eyes warrants further investigation.

Femtosecond Laser Trabeculotomy in Perfused Human Cadaver Anterior Segments: A Novel, Noninvasive Approach to Glaucoma Treatment

Purpose

The purpose of this study was to investigate femtosecond laser trabeculotomy (FLT) in a clinically relevant manner (i.e., delivering the surgical laser beam through the cornea of the intact, human anterior segment to create channels from the anterior chamber into the Schlemm's canal) and to investigate the effect of this treatment on intraocular pressure in perfused human anterior segments.

Methods

Perfused human anterior segments (15 eyes) received either FLT treatment (n = 8) or a sham-treatment (n = 7). Intraocular pressure (IOP) in the perfused samples was recorded before and after treatment. Spectral domain optical coherence tomography, second harmonic generation imaging, and transmission electron microscopy were used to investigate the FLT channels.

Results

The FLT group (n = 7, 1 eye excluded) had a statistically significant reduction in mean IOP of 20.2% from baseline after treatment (5.06 ± 1.46 mm Hg to 4.04 ± 1.63 mm Hg; P < 0.0005), whereas the control group (n = 7) remained statistically unchanged (7.72 ± 3.45 mm Hg to 7.78 ± 3.51 mm Hg; P < 0.71). Imaging confirmed that the channels traversed the entire trabecular meshwork into the Schlemm's canal.

Conclusions

This study has provided the first direct evidence supporting the feasibility of clinically applicable, noninvasive femtosecond laser trabeculotomy for the treatment of glaucoma. Various imaging modalities revealed minimal collateral damage to adjacent issues.

Translational Relevance

This work demonstrates noninvasive femtosecond laser trabeculotomy in a laboratory setting that is clinically relevant.

[Comparative evaluation of hypotensive effectiveness of topical monotherapy and selective laser trabeculectomy]

PURPOSE

Comparison of the hypotensive effects of selective laser trabeculoplasty (SLT) and drug therapy in patients with newly diagnosed primary open-angle glaucoma (POAG) and ocular hypertension.

MATERIAL AND METHODS

Thirty patients (30 eyes) with newly diagnosed ophthalmic hypertension or POAG were observed. Patients of the 1st group (15 eyes) underwent standard SLT as a starting treatment, patients of the 2nd group (15 eyes) were prescribed monotherapy with a prostaglandin analog. Corneal compensated intraocular pressure (IOPcc) was measured for each patient using Ocular Response Analyzer («Reichert Technologies», USA). The observation period lasted 6 months.

RESULTS

During the 6-months follow-up, tafluprost was found to effectively reduce IOP in 93.3% of cases, SLT - in 73.3% of cases. There were no statistically significant differences in hypotensive effectiveness between the two compared treatments, which amounted to 27.9-28.5% reduction from the baseline values.

CONCLUSION

Selective laser trabeculectomy and topical drug therapy have shown similar hypotensive effectiveness during the 6-months follow-up when used as the initial therapy for POAG.

Five-Year Long-Term Follow-Up of Selective Laser Trabeculoplasty in Open-Angle Glaucoma

PURPOSE

Selective laser trabeculoplasty (SLT) is known as a safe laser therapy for an effective reduction in intraocular pressure (IOP). The aim of this study was to examine the therapeutic success of SLT in open-angle glaucoma (OAG) patients with a long-term follow-up of 5 years.

METHODS

Forty-six eyes of forty OAG patients, some with previous intraocular surgery, underwent SLT (24 males, 16 females). Therapeutic success was categorized as: category (I) - IOP reduction ≤ 21 mmHg and > 20% compared to baseline IOP with additional glaucoma medication; category (II) - IOP reduction ≤ 18 mmHg and > 30% compared to baseline IOP with additional glaucoma medication; category (III) - IOP reduction ≤ 18 mmHg without any additional glaucoma medication at all follow-ups. Therapeutic failure was defined as the necessity of any further glaucoma surgery (IV).

RESULTS

(1) SLT was well tolerated in all eyes, and no severe side effects or complications were recorded. (2) After 1-year follow-up, therapeutic success was 27% (I), 30% (II), and 3% (III). The therapeutic failure rate was 40% (IV). (3) After 2 years follow-up, therapeutic success was 7% (I), 10% (II), and 0% (III). The therapeutic failure rate was 83% (IV). (4) After 3 years follow-up, the therapeutic failure rate increased up to 100% (IV).

CONCLUSION

SLT seemed to be effective in lowering IOP in the first year in the present cohort, however, the long-term effect is low and additional local therapy or surgical interventions are necessary.

Mid-term results of patterned laser trabeculoplasty for uncontrolled ocular hypertension and primary open angle glaucoma

AIM

To describe the safety and efficacy of patterned laser trabeculoplasty (PLT) as an adjunctive treatment in primary open angle glaucoma (POAG) and ocular hypertension (OHT) after 18-month follow-up in Hispanic population.

METHODS

A single-center, retrospective study was conducted. All patients with OHT or POAG undergoing PLT from June 2016 to August 2016 were included in the study. Investigated parameters were intraocular pressure (IOP), the number of IOP-lowering medications, best corrected visual acuity (BCVA), laser parameters and postoperative adverse events. Primary efficacy outcome measures were the proportion of eyes achieving an IOP reduction ≥20% at 18mo versus baseline medicated IOP or a reduction in the number of medications while maintaining IOP values.

RESULTS

From 40 PLT-treated eyes (mean baseline IOP 20.3±1.7 mm Hg), 24 patients were analyzed (age 63.4±7.3y). The mean IOP reductions from baseline across visits (months 1, 3, 6, 9, 12, and 18) ranged from 14.1% to 20.8%. Success rate after 18-month follow-up was 61.7% with a mean IOP of 16±3.2 mm Hg (P<0.001). The number of glaucoma IOP-lowering medications per eye (preoperative 2.1±1.1 and postoperative 2.3±1.1, P=0.86) and the mean BCVA (preoperative 0.10±0.22 and postoperative 0.11±0.22 logMAR, P=0.42) remained stable. Adverse events comprised transitory IOP spikes in 4 eyes (10%) and peripheral anterior synechiae in 7 eyes (17.5%).

CONCLUSION

Mid-term results of PLT show that this procedure may be an efficacious and safe technique to approach medically uncontrolled OHT or POAG patients.

Efficacy of Selective Laser Trabeculoplasty after iStent Implantation in Primary Open-Angle Glaucoma

iStent implantation is thought to augment the trabecular outflow channel in the anterior segment of the eye. We hypothesized that iStent with subsequent selective laser trabeculoplasty (SLT) would better control the intraocular pressure (IOP) compared to standalone SLT in patients with primary open-angle glaucoma (POAG). We, therefore, determined if the presence of an iStent combined with SLT was statistically associated with IOP lowering compared to standalone SLT. Through retrospective electronic medical record review, records of 824 eyes from 440 patients who received primary SLT without a history of iStent were considered. Additionally, 42 eyes from 28 patients who received SLT after combined phacoemulsification and iStent implantation that failed to control intraocular pressure (IOP) and/or the progression of the disease were retrospectively reviewed. IOP and number of medications, which were tracked in each patient for up to 12 months post laser, were also examined. Successful outcome was defined as a statistically significant reduction in IOP or number of medications at 6 months. As defined in univariate analysis (p ≤ 0.01), multivariate analysis included iStent, age, sex, race, and initial IOP as variables. IOP reduction was statistically associated with patients pre-SLT IOP (p < 0.001) but not with patients with iStent (p = 0.222). Medication reduction was statistically associated with the pre-SLT number of medications (p < 0.001) and iStent (p < 0.001). In eyes that received SLT, iStent was not statistically associated with a greater reduction in IOP compared to controls, but was associated with a higher reduction in the overall number of medications used 6 months after receiving SLT. The work presented should guide clinicians to consider SLT as an effective therapy after iStent implantation, in terms of glaucoma medication reduction in iStent patients, but clinicians should know that the presence of an iStent does not necessarily make subsequent SLT more effective at lowering IOP.

Selective laser trabeculoplasty lowered the untreated fellow eye long-term intraocular pressure: a 3-year observational study

To explore the long-term intraocular pressure (IOP)-lowering effect of monocular selective laser trabeculoplasty (SLT) in the untreated fellow eyes of open-angle glaucoma (OAG) patients. This was a retrospective observational study. Consecutive Chinese OAG patients who received monocular SLT treatment were included in this study. One hundred and eighty degree SLT was conducted as adjunctive treatment when anti-glaucoma medication was not sufficiently effective after clinical evaluation. Treatment success was defined as more than 20% IOP reduction of the baseline IOP levels. IOP-decreasing amplitude and SLT success rate of both eyes were investigated during the 3-year follow-up period. Age, gender, baseline IOP levels, number of medications, and SLT energy parameters were analyzed to determine its influence on IOP reduction effect and treatment success rate. A total of 32 Chinese OAG patients were included in this study and 25 of them completed the 3-year follow-ups. Their pretreatment IOPs were 18.85 ± 2.81 mmHg in the treated eyes and 17.38 ± 2.37 mmHg in the fellow eyes. At the 3-year follow-up visits, IOP decreased to 2.76 ± 3.72 mmHg (14.16%) in the treated eyes and 2.16 ± 2.73 mmHg (11.95%) in the fellow eyes, with a success rate of 47.83% (11 in 23 cases) and 44.00% (11 in 25 cases), respectively. IOPs of both eyes decreased significantly after SLT from 6 months and lasted to 3 years after treatment. Baseline IOP level was positively correlated with IOP reduction in the treated eyes and other factors were not correlated with IOP reduction and treatment success. Monocular SLT treatment as adjunctive treatment could lower IOPs not only in the treated eyes but also in the untreated eyes in poor medication-controlled OAG patients. In addition, its IOP reduction effect could last to 3 years after treatment in clinical practice.

Intraocular Pressure Reduction by Femtosecond Laser Created Trabecular Channels in Perfused Human Anterior Segments

Purpose

This study investigated the initial feasibility of using femtosecond laser trabeculotomy (FLT) to create open channels through the trabecular meshwork into Schlemm's canal to lower intraocular pressure (IOP) in a perfused anterior segment model.

Methods

Human anterior segments (12 eyes) were assigned to either treatment (n = 6) or sham treatment (n = 6) groups. Both groups were perfused until a baseline IOP was recorded upon which a direct FLT treatment or a sham treatment was administered. IOP was recorded before and after the treatment. Spectral domain optical coherence tomography and second harmonic generation imaging we used to investigate the FLT channels.

Results

In the FLT group, there was a significant mean decrease in the IOP of 22% compared with the pre-FLT IOP (7.13 ± 2.95 mm Hg to 5.34 ± 1.62 mm Hg; P < 0.05). In the control group, the post-sham IOP remained relatively unchanged compared with the pre-sham IOP (6.39 ± 3.69 mm Hg to 6.67 ± 4.12 mm Hg).

Conclusions

The results of this study indicate that FLT treatment can significantly decrease the IOP in a perfusion model and may provide a potential noninvasive treatment option for primary open angle glaucoma.

Translational Relevance

Investigating the use of femtosecond lasers for photodisrupting the trabecular meshwork can lead to a clinically relevant alternative to current glaucoma procedures.

Low-energy Selective Laser Trabeculoplasty Repeated Annually: Rationale for the COAST Trial

The recent Laser in Glaucoma and Ocular Hypertension Trial provided the evidentiary basis for a paradigm shift away from the historical medication-first approach to glaucoma--which has numerous limitations, the most important of which is poor adherence to therapy --and toward a laser-first approach. Now 20 years after its commercialization, selective laser trabeculoplasty (SLT) is routinely performed consistently with its initial description, with energy titrated to the appearance of fine, champagne-like cavitation bubbles. A recent data set suggested that lower energy SLT, applied as primary therapy and repeated annually irrespective of intraocular pressure--rather than pro re nata when its effect wanes and irrespective of intraocular pressure rises --yields longer medication-free survival than standard energy SLT repeated pro re nata. A new study--Clarifying the Optimal Application of SLT Therapy --has been initiated to explore this preliminary finding in a pair of consecutive randomized trials. Herein, we provide an evidence-based rationale for the use of low-energy SLT repeated annually as primary therapy for mild to moderate primary open-angle glaucoma or high-risk ocular hypertension.

Outcomes of selective laser trabeculoplasty in corticosteroid-induced ocular hypertension and glaucoma

PURPOSE

To report the outcomes of selective laser trabeculoplasty (SLT) in lowering intraocular pressure (IOP) in patients with steroid-induced ocular hypertension and glaucoma.

METHODS

A retrospective chart review of patients who underwent SLT for steroid-induced ocular hypertension or glaucoma between January 2014 and October 2018. Success of SLT was defined as ⩾20% IOP reduction from baseline without further medical or surgical intervention and/or a reduction in the number of glaucoma medications by ⩾1 from baseline while maintaining the target IOP. Main outcome measures were change in IOP from baseline and reduction in the number of medications post-laser.

RESULTS

A total of 25 eyes of 17 patients were included in the study. The mean duration of follow-up was 18.8 ± 4.5 months. IOP decreased from 23.7 ± 6.7 mmHg pre-laser to 14.4 ± 3.2 mmHg post-laser, at the last follow-up visit (p < 0.001). The mean number of medications was 1.8 ± 1.6 medications pre-laser and 1.4 ± 1.3 medications post-laser (p = 0.262). The overall success rate at 12 months was 72%. No visually significant complications were encountered during the whole duration of follow-up.

CONCLUSION

SLT is a safe and effective procedure that can result in well-controlled IOP in patients with steroid-induced ocular hypertension and glaucoma.

Outcome After Selective Laser Trabeculoplasty for Glaucoma Treatment in a Thai Population

Purpose

The study aimed to evaluate the efficacy and predictive factors of success after selective laser trabeculoplasty (SLT) for treating various types of open-angle glaucoma in a Thai population.

Design

The study employed a retrospective cohort design.

Materials and Methods

The study retrospectively recruited Thai subjects diagnosed with open-angle glaucoma receiving first time selective laser trabeculoplasty. Primary open-angle glaucoma (POAG), ocular hypertension (OHT) and other types of open-angle glaucoma were included. Reduced intraocular pressure (IOP) of 20% or decreased number of antiglaucoma drugs usage after SLT was defined as success. Various parameters were analyzed for association with SLT success.

Results

Ninety-six eyes were recruited in the study. Mean pre- and postSLT IOP were 19.31±3.59 and 15.04±3.13 mmHg, respectively. IOP decreased significantly in all follow-up visits (p<0.001). Overall, 59.4% met the treatment endpoint. More than 10% postSLT IOP elevation at 1 hour was the only covariate positively associated with SLT success in both univariate (odds ratio (OR) = 1.042, p = 0.037) and multivariate analyses (OR = 1.040, p = 0.046). Underlying hypertension and preSLT IOP were negatively associated with SLT success in both univariate (OR = 0.970, p = 0.026, OR = 0.955, p < 0.001) and multivariate analysis (OR = 0.970, p = 0.026, OR = 0.991, p < 0.001).

Conclusion

IOP significantly decreased as well as the number of antiglaucoma drugs needed after SLT. More than 10% postSLT IOP elevation at 1 hour was a positive predictor whereas systemic hypertension and preSLT IOP were negative predictors of SLT success.

Micropulse laser trabeculoplasty under maximal tolerable glaucoma eyedrops: treatment effectiveness and impact of surgical expertise

AIM

To evaluate the effectiveness of micropulse laser trabeculoplasty (MLT) for eyes with open angle glaucoma (OAG) under maximal tolerable glaucoma eyedrops and to assess the effect of expertise performing MLT on its clinical effectiveness.

METHODS

Medical records of 42 consecutive eyes of 34 patients diagnosed with OAG who underwent MLT were retrospectively reviewed. The effectiveness was determined using the Kaplan-Meier survival analysis. Failure was defined as an intraocular pressure (IOP) reduction of <20% from baseline, an IOP >21 mm Hg during two consecutive follow-up visits, or surgical intervention for OAG. To determine the impact of MLT surgical expertise on clinical effectiveness, the eyes were divided into two groups according to whether the procedure was conducted by an experienced specialist (defined as a glaucoma specialist who had conducted at least ten MLT procedures) or a less experienced glaucoma specialist. The difference in expertise was determined using a log-rank test.

RESULTS

MLT was conducted by three glaucoma specialists. The overall survival rates were 0.76, 0.48, and 0.44 at 1, 3, and 6mo, respectively. The survival rates for MLT performed by a less experienced glaucoma specialist were 0.62, 0.31, and 0.25 (n=21 eyes) at 1, 3, and 6mo, respectively, whereas the survival rates for MLT performed by an experienced glaucoma specialist were 0.90, 0.64, and 0.64 (n=21 eyes) at 1, 3, and 6mo, respectively. The log-rank test showed a significant difference in the survival curves of the two groups (P=0.0061).

CONCLUSION

The 6-month effectiveness of MLT for controlling IOP is relatively limited in eyes with OAG using maximal tolerable glaucoma eyedrops. However, its effectiveness may be improved if performed by a glaucoma specialist with sufficient MLT experience.

Effectiveness of Selective Laser Trabeculoplasty Applied to 360° vs. 180° of the Angle

Purpose

To compare the effectiveness and safety of 360° and 180° of Selective Laser Trabeculoplasty (SLT) for the treatment of elevated intraocular pressure (IOP).

Methods

Retrospective cohort study. The main outcome measure was the Kaplan–Meier analysis comparing the cumulative probabilities of survival between the 360° and 180° SLT groups in terms of IOP reduction. Success was defined as ≥20% IOP reduction from baseline with an IOP between 5–18 mmHg and ≤1 glaucoma medication added postoperatively. Additional outcome measures included changes in average IOP, number of glaucoma medications, and the incidence of postoperative IOP spikes. Measurements were obtained at 6 weeks, 1 year, and 2 years postoperatively.

Results

Two hundred and fifty-eight eyes of 258 patients were included in the 360° group, and 196 eyes of 196 patients were included in the 180° group. The mean IOP reductions at 2 years were 2.21 ± 2.02 mmHg and 2.43 ± 1.81 mmHg (p=0.33) in the 180° and 360° groups, respectively. There were no significant differences in the incidence of postoperative IOP spikes between the two groups. There was a significant difference in the survival curves of the two groups (p=0.035). The Cox proportional-hazard model indicated that 360° of SLT application was a significant predictor of long-term success (p=0.030).

Conclusions

360° of SLT application seems to provide for greater long-term IOP control than 180° of application without putting patients at an elevated risk for postoperative IOP spikes.

The Effect of Selective Laser Trabeculoplasty on Intraocular Pressure in Patients with Dexamethasone Intravitreal Implant-Induced Elevated Intraocular Pressure

Introduction

To assess the safety and efficacy of selective laser trabeculoplasty (SLT) for ocular hypertension (OHT) induced by a dexamethasone (DEX) intravitreal implant.

Materials and Methods

We performed a retrospective study of patients who underwent an SLT procedure for ocular hypertension induced by injection of a DEX intravitreal implant. Patients had, at least, one injection of the DEX-implant for symptomatic macular edema. SLT was delivered to 360° of the trabecular meshwork in two sessions. The primary outcome was a decrease in IOP, evaluated at one, three, and six months after the SLT procedure.

Results

Twenty-six eyes of 22 patients were included. The mean intraocular pressure (IOP) measured after DEX-implant injection was 25.4 ± 5.4 mmHg, and the mean increase in IOP was 35.8 ± 14.6%. The mean follow-up after SLT was 18.3 ± 7.7 months. After SLT, the mean IOP dropped by 30.9% at one month (16.9 ± 4.5 mmHg, p=0.01), 33.6% at three months (16.0 ± 2.7 mmHg, p < 0.01), and 34.9% at six months (15.6 ± 2.1 mmHg, p < 0.01). Each patient had a minimum follow-up of 6 months after SLT. Eight eyes (31%) received a second DEX-implant injection after the SLT procedure without experiencing an increase in the IOP above 21 mmHg or >20%. No glaucoma surgery was required during the follow-up. The mean number of medications (1.65 ± 1.36) was significantly reduced at one (1.19 ± 1.20, p=0.04), three (0.96 ± 1.03, p < 0.01), and six months (0.77 ± 0.95, p < 0.01) after SLT.

Conclusion

SLT is an effective and safe procedure to control OHT following DEX-implant intravitreal injection.

Selective laser trabeculoplasty versus drops for newly diagnosed ocular hypertension and glaucoma: the LiGHT RCT

BACKGROUND

Newly diagnosed open-angle glaucoma (OAG) and ocular hypertension (OHT) are habitually treated with intraocular pressure (IOP)-lowering eyedrops. Selective laser trabeculoplasty (SLT) is a safe alternative to drops and is rarely used as first-line treatment.

OBJECTIVES

To compare health-related quality of life (HRQoL) in newly diagnosed, treatment-naive patients with OAG or OHT, treated with two treatment pathways: topical IOP-lowering medication from the outset (Medicine-1st) or primary SLT followed by topical medications as required (Laser-1st). We also compared the clinical effectiveness and cost-effectiveness of the two pathways.

DESIGN

A 36-month pragmatic, unmasked, multicentre randomised controlled trial.

SETTINGS

Six collaborating specialist glaucoma clinics across the UK.

PARTICIPANTS

Newly diagnosed patients with OAG or OHT in one or both eyes who were aged ≥ 18 years and able to provide informed consent and read and understand English. Patients needed to qualify for treatment, be able to perform a reliable visual field (VF) test and have visual acuity of at least 6 out of 36 in the study eye. Patients with VF loss mean deviation worse than -12 dB in the better eye or -15 dB in the worse eye were excluded. Patients were also excluded if they had congenital, early childhood or secondary glaucoma or ocular comorbidities; if they had any previous ocular surgery except phacoemulsification, at least 1 year prior to recruitment or any active treatment for ophthalmic conditions; if they were pregnant; or if they were unable to use topical medical therapy or had contraindications to SLT.

INTERVENTIONS

SLT according to a predefined protocol compared with IOP-lowering eyedrops, as per national guidelines.

MAIN OUTCOME MEASURES

The primary outcome was HRQoL at 3 years [as measured using the EuroQol-5 Dimensions, five-level version (EQ-5D-5L) questionnaire]. Secondary outcomes were cost and cost-effectiveness, disease-specific HRQoL, clinical effectiveness and safety.

RESULTS

Of the 718 patients enrolled, 356 were randomised to Laser-1st (initial SLT followed by routine medical treatment) and 362 to Medicine-1st (routine medical treatment only). A total of 652 (91%) patients returned the primary outcome questionnaire at 36 months. The EQ-5D-5L score was not significantly different between the two arms [adjusted mean difference (Laser-1st - Medicine-1st) 0.01, 95% confidence interval (CI) -0.01 to 0.03; p = 0.23] at 36 months. Over 36 months, the proportion of visits at which IOP was within the target range was higher in the Laser-1st arm (93.0%, 95% CI 91.9% to 94.0%) than in the Medicine-1st arm (91.3%, 95% CI 89.9% to 92.5%), with IOP-lowering glaucoma surgery required in 0 and 11 patients, respectively. There was a 97% probability of Laser-1st being more cost-effective than Medicine-1st for the NHS, at a willingness to pay for a quality-adjusted life-year of £20,000, with a reduction in ophthalmology costs of £458 per patient (95% of bootstrap iterations between -£585 and -£345).

LIMITATION

An unmasked design, although a limitation, was essential to capture any treatment effects on patients' perception. The EQ-5D-5L questionnaire is a generic tool used in multiple settings and may not have been the most sensitive tool to investigate HRQoL.

CONCLUSIONS

Compared with medication, SLT provided a stable, drop-free IOP control to 74.2% of patients for at least 3 years, with a reduced need for surgery, lower cost and comparable HRQoL. Based on the evidence, SLT seems to be the most cost-effective first-line treatment option for OAG and OHT, also providing better clinical outcomes.

FUTURE WORK

Longitudinal research into the clinical efficacy of SLT as a first-line treatment will specify the long-term differences of disease progression, treatment intensity and ocular surgery rates between the two pathways.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN32038223.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 31. See the NIHR Journals Library website for further project information.

Experimental study of trabecular tissue repair for corneal defect in rabbits

AIM

To investigate the mechanism and effect of trabecular tissue repair for corneal defect, and to provide a theoretical basis for its clinical application.

METHODS

Trabeculectomy was performed on 40 (80 eyes) of 70 New Zealand white rabbits. Take trabecular tissue for backup. Thirty (30 eyes) corneal defect models were made, trabecular tissue was filled in the corneal defect, and the oblique cross stitch was used to suture the corneal laceration and debridement. Anterior segment image and optical coherence tomography (OCT) were performed at the time 1d, 1wk, 1 and 3mo after the model was made. After the observation, the cornea was taken and stained with trypanosome blue-alizarin red and the pathological tissue was examined.

RESULTS

Observation 1wk after surgery, the area of corneal defect was edema, but the corneal curvature was basically normal, and the anterior chamber existed under slit lamp. After 3mo of observation, most corneal defects were repaired in the form of corneal leucoma and corneal macula (73.3%), the filled trabecular tissue gradually became transparent, fused tightly with the corneal tissue, and the corneal curvature was relatively smooth. But in one case, the trabecular planter was partially detached, no serious complications such as corneal laceration occurred after the stitches were removed.

CONCLUSION

The trabecular tissue structure is similar to the corneal, and it can be used as a substitute for the corneal tissue defect by providing fiber scaffolds and cell amplification differentiation, and lay a foundation for the second-stage surgical treatment.

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.

Towards Automatically Controlled Dosing for Selective Laser Trabeculoplasty

Purpose

Selective laser trabeculoplasty (SLT) is a treatment option for open-angle glaucoma; however, it lacks an instant evidence for successful irradiation. So far ophthalmologists use the visible appearance of permanent champagnelike bubbles (macro bubbles) as an indicator for appropriate pulse energy. We hypothesize that micro bubbles, which start energetically far below the appearance of macro bubbles, already trigger the therapeutic benefit. Here we present two methods to capture the onset of these micro bubbles.

Methods

The trabecular meshwork of freshly enucleated porcine eye globes was irradiated with a series of 15 pulses with a pulse duration of 1.7 μs and with increasing energy at a repetition rate of 100 Hz per each spot of 200 μm in diameter. An optical and an optoacoustic method have been developed and appropriate algorithms investigated towards the real-time detection of the onset of micro bubbles.

Results

Both observation methods are capable of detecting micro bubble nucleation. Threshold radiant exposures were found at 310 ± 137 mJ/cm². By combination of both methods a sensitivity and specificity of 0.96 was reached.

Conclusions

In case that the therapeutically demanded pressure reduction is already achieved with these micro bubbles, which needs to be proven clinically, then the methods presented here can be used in an automatic feedback loop controlling the laser irradiation. This will unburden the clinicians from any dosing during SLT.

Translational Relevance

Automatic real-time pulse energy dosing based on the formation of micro bubbles in SLT significantly improves and facilitates the treatment for the physician.

Primary Selective Laser Trabeculoplasty for Open-Angle Glaucoma and Ocular Hypertension: Clinical Outcomes, Predictors of Success, and Safety from the Laser in Glaucoma and Ocular Hypertension Trial

PURPOSE

To report clinical efficacy, predictors of success, and safety of primary selective laser trabeculoplasty (SLT) used in treatment-naive patients with open-angle glaucoma (OAG) or ocular hypertension (OHT).

DESIGN

Post hoc analysis of a multicenter, prospective, randomized, controlled trial.

PARTICIPANTS

Treatment-naive patients with OAG or OHT.

METHODS

Patients randomized to SLT or topical medication and treated to predefined target intraocular pressures (IOPs) requiring ≥20% IOP reduction from baseline for all disease severity levels.

OUTCOME MEASURES

Initial (early) absolute IOP-lowering at 2 months. Achievement of drop-free disease-control: meeting target IOP without disease progression or need for additional topical medication over 36 months after SLT. Predictors of early absolute IOP-lowering and drop-free disease-control after single initial SLT. Frequency of laser-related complications.

RESULTS

A total of 611 eyes (195 OHT and 416 OAG) of 355 patients received SLT, and 622 eyes (185 OHT and 437 OAG) of 362 patients received topical medication at baseline. Early absolute IOP-lowering after SLT was no different between OHT and OAG eyes (adjusted mean difference = -0.05 mmHg; 95% confidence interval [CI], -0.6 to 0.5 mmHg; P = 0.85). No difference was noted in early absolute IOP-lowering between topical medication and primary SLT (adjusted mean difference = -0.1 mmHg; 95% CI, -0.6 to 0.4 mmHg; P = 0.67). Early absolute IOP-lowering with primary SLT was positively associated with baseline IOP (coefficient 0.58; 95% CI, 0.53-0.63; P < 0.001) and negatively with female gender (coefficient -0.63; 95% CI, -1.23 to -0.02; P = 0.04). At 36 months, 536 eyes (87.7% of 611 eyes) of 314 patients (88.5% of 355 patients) were available for analysis. Some 74.6% of eyes (400 eyes) treated with primary SLT achieved drop-free disease-control at 36 months; 58.2% (312 eyes) after single SLT. Total SLT power and 2-month IOP were predictors of drop-free disease-control at 36 months after single SLT. Six eyes of 6 patients experienced immediate post-laser IOP spike (>5 mmHg from pretreatment IOP) with 1 eye requiring treatment.

CONCLUSIONS

Primary SLT achieved comparable early absolute IOP-lowering in OHT versus OAG eyes. Drop-free disease-control was achieved in approximately 75% eyes at 36 months after 1 or 2 SLTs, the majority of these after single SLT. These analyses are exploratory but support primary SLT to be effective and safe in treatment-naive OAG and OHT eyes.

Micropulse Trabeculoplasty in Open Angle Glaucoma

Background:

We report the effect of micropulse laser trabeculoplasty (MLT) in the intraocular pressure (IOP) of patients with uncontrolled open-angle glaucoma (OAG).

Materials and Methods:

In this retrospective review, 30 eyes with OAG were treated with a single session of MLT at the Vista Clinic in Lima Perú. We used a 532 nm frequency doubled Nd: YAG laser to 360° of the trabecular meshwork with a power of 1000 mW, 15% of the duty cycle, and 300 ms of exposure. The IOP was measured at baseline and at 1 day, 1 week, 3 months, and 6 months post-treatment and were followed up for one last control.

Results:

The mean baseline IOP was 15.6 mmHg and in the last control was 12.8 mmHg, mean follow-up time of 19 months (±10 standard deviation [SD]). The mean reduction of IOP in the 1^st day was 1.6 mmHg (±2.6 SD) and 1.2 mmHg (±3.3 SD) in the last follow-up. The mean percentage of IOP reduction was 17.9% and 7 eyes (40%) had IOP reduction >20%. No statistical significant difference in relation to demographic characteristics of the patients. The greatest reduction was achieved in the 1^st day with a median of 2.00 (P < 0.001). A tendency to achieve a higher reduction of IOP in patients with higher baseline IOP was found but was not statistically significant. No adverse reactions occurred.

Conclusions:

MLT slightly reduced the IOP in a few patients with uncontrolled OAG for a very short time and may not be suitable for these patients.

A cost minimisation analysis comparing iStent accompanying cataract surgery and selective laser trabeculoplasty versus topical glaucoma medications in a public healthcare setting in New Zealand

PURPOSE

To produce an economic comparison of the iStent ab interno trabecular microbypass implant accompanying cataract surgery and selective laser trabeculoplasty (SLT) as first-line treatment versus topical medications for open-angle glaucoma in New Zealand in 2016.

METHODS

The current annual costs of 19 available fully subsidised topical glaucoma medications by Pharmaceutical Management Agency (Pharmac) in 2016 were identified. Adjustments for pharmacist prescribing charges and previously described wastage levels were applied. The costs to perform iStent implantation and the cost to perform SLT were obtained from the local distributors, with the latter taking into account staff and consumable cost. Procedure costs divided by eye drops' cost produced a break-even level in equivalent years of eye drops use.

RESULTS

The range of annual eye drop cost was NZD$42.25 to NZD$485.11, with an average of NZD$144.81. Comparison of annual eye drop cost with iStent cost revealed 3 of 19 (15.8%) drops breaking even within 5 years, 9 of 19 (47.3%) within 10 years, and 12 of 19 (63.2%) within 15 years. The cost of bilateral SLT performed by a consultant was NZD$102.30 (breaking even in 0.71 years). The equivalent cost for a registrar was NZD$97.59 (breaking even in 0.67 years).

CONCLUSION

Economically, the iStent would appear to be a reasonably cost-effective treatment for glaucoma patients undergoing cataract surgery in a public healthcare setting in New Zealand, particularly for those using more expensive topical glaucoma medications, whilst SLT appears to be a worthwhile consideration as a first-line treatment for glaucoma in New Zealand.

Cystoid macular edema following selective laser trabeculoplasty in a patient with ocular hypertension

PURPOSE

Presentation of a case with ocular hypertension who developed cystoid macular edema (CME) following selective laser trabeculoplasty (SLT).

CASE REPORT

A 62-year-old male patient who had undergone phacoemulsification surgery for traumatic cataract 9 years ago was on ocular hypertension treatment for the last 5 years. Due to uncontrolled intraocular pressure and side effect of medications, a 360° SLT was performed. The patient returned with decrased visual acuity 1 week after the procedure. There was CME in the treated eye. It healed completely after topical prednisolone acetate QID and nepafenac QID for 1 week, and no recurrence was observed during follow-ups.

CONCLUSION

Cystoid macular edema may occur following SLT treatment in patients with previous traumatic cataract surgery which responds to topical treatment.

CD163+ macrophages infiltrate axon bundles of postmortem optic nerves with glaucoma

PURPOSE

Prior research in animal models has shown that macrophages and microglia play an important role in pathogenesis of glaucoma, but the phenotype and distribution of macrophages in human glaucomatous tissue have not been sufficiently characterized.

METHODS

We analyzed H&E, CD68-, and CD163-immunostained slides from 25 formaldehyde-fixed, paraffin-embedded autopsy eyes: 12 control eyes and 13 eyes with glaucoma. The diagnosis of glaucoma was made based on a history of glaucoma as reported in the medical record and histological changes characteristic of glaucoma. Glaucoma cases and controls were matched in terms of age, sex, and race.

RESULTS

Qualitative analysis of the conventional outflow pathway and the optic nerve revealed that all eyes contained CD163+ cells but a negligible number of CD68+ cells. CD163+ macrophages infiltrated the trabecular meshwork and surrounded Schlemm's canal of normal eyes and eyes with glaucoma, but the pattern was variable and qualitatively similar between groups. In optic nerves of control eyes, CD163+ macrophages were present at low levels and restricted to septa between axon bundles. In glaucomatous optic nerves, the number of CD163+ cells was increased both qualitatively and quantitatively (glaucoma 5.1 ± 0.6 CD163+ cells/mm², control 2.5 ± 0.3 CD163+ cells/mm², p < 0.001), with CD163+ cells infiltrating axon bundles in cases of both mild and severe diseases.

CONCLUSIONS

The increase in CD163+ cell number in eyes with mild and severe glaucoma is the first demonstration of macrophage infiltration in glaucomatous human optic nerves. This finding supports a role for macrophages in glaucoma pathogenesis and progression.

Efficacy of selective laser trabeculoplasty in primary angle closure disease

BACKGROUND

To study the role of selective laser trabeculoplasty (SLT) in intraocular pressure (IOP) reduction in post-laser iridotomy primary angle-closure disease patients with inadequately controlled IOP.

METHODS

In this prospective cross-sectional study, 34 patients with primary angle-closure disease with post-laser iridotomy open angles up to at least 180° were recruited. Following SLT, patients were examined at 1 day, 1 week, 1 and 3 months, 6 months and 1 year post SLT.

RESULTS

Data of 34 patients (34 eyes; 8 males and 26 females), with a mean age of 57.80 ± 6.44 years, were analysed. The reduction in IOP at each follow-up visit was significant (p < 0.001). The maximum reduction in IOP was noticed on post-laser day 1 and the least reduction was noticed 1 week post laser. Post-SLT range of IOP reduction varied from 9 to 46% at 1 year, which indicates the variability of a response to SLT. Mean IOP in both primary angle closure (PAC) and primary angle closure glaucoma (PACG) groups was comparable at all visits except at post-SLT week 1 when IOP in the PACG group was significantly higher than that in the PAC group (p = 0.035). None of the patients complained of pain and/or discomfort or had any clinically significant anterior segment inflammation on any of the follow-up visits. None of the patients underwent repeat SLT or surgery. The mean pre-SLT and post-SLT visual field index at 1-year follow-up was 95.47 ± 3.58 and 95.90 ± 4.13, respectively, which was not significant (p = 0.84).

CONCLUSIONS

High baseline IOP significantly correlated with reduction in IOP. Our results suggest that SLT is a safe, cost-effective modality for reducing IOP in primary angle-closure disease with patent laser iridotomy with a visible trabecular meshwork.

A Review of the Clinical Usefulness of Selective Laser Trabeculoplasty in Exfoliative Glaucoma

In the last decade, selective laser trabeculoplasty (SLT) has been commonly used in the management of several different types of glaucoma, as either primary or adjunct therapy. The technique has an excellent safety profile and is at least as effective as argon laser trabeculoplasty. Although the actual mechanism of action of SLT remains unclear, evidence has shown that it does not induce morphologically evident trabecular meshwork alterations. SLT's non-disruptive mode of action offers the advantage of repeatability. Exfoliation glaucoma (XFG) is a secondary open-angle glaucoma with unfavorable intraocular pressure (IOP) characteristics, which typically carries a poorer long-term prognosis than primary open-angle glaucoma. Consequently, patients with XFG often need multiple medications to achieve IOP levels that prevent disease progression. Because complicated pharmacotherapy regimens undermine the long-term tolerability and compliance of patients with XFG, options such as SLT may decrease the burden of multiple therapies and ultimately improve prognosis. In fact, SLT may be a particularly attractive option in XFG because the pigment-laden trabecular tissue of these patients enhances the absorption of laser energy and thus augments the biologic effects induced by this treatment. The current article reviews the postulated mechanisms of action of SLT, discusses practical aspects of SLT therapy, and examines selected peer-reviewed literature pertaining to the clinical usefulness of this modality in XFG patients.

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.

Feasibility of laser trabeculoplasty in angle closure glaucoma: a review of favourable histopathological findings in narrow angles

Selective laser trabeculoplasty (SLT) has been indicated as a safe and efficient treatment for primary open-angle glaucoma; however, recent studies have also shown positive results with the use of SLT in some clinical conditions related to primary angle-closure glaucoma (PACG). Despite the potential benefits of SLT in selected cases of PACG, the mechanisms underlying the modifications in the trabecular meshwork tissue of patients with PACG are poorly understood. This narrative review approached both the current, limited knowledge about the histological changes observed in different forms of PACG and the clinical results of SLT treatment for PACG. Favourable outcomes of SLT in patients with PACG, specifically in areas of non-occluded angle, need further substantiation through large controlled clinical trials. A deeper understanding of the biomolecular changes of those areas is essential to improve both laser technical details and the clinical efficacy of SLT therapy.

Impact of laser pulse duration on the reduction of intraocular pressure during selective laser trabeculoplasty

PURPOSE

To evaluate the efficacy of selective laser trabeculoplasty (SLT) to lower intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG), normal tension glaucoma (NTG) or ocular hypertension (OHT), when performed with laser pulse duration of 1 ns compared with standard 3-5 ns.

METHODS

Bilateral SLT with a 532 nm Q-switched neodymium-doped yttrium aluminium garnet laser was conducted in 30 patients (60 eyes) with POAG (n = 5), NTG (n = 2) or OHT (n = 23). Pulse duration was 1 ns in the right eye (30 eyes; cases) and 3-5 ns in all left eyes (controls). Main outcome measures were IOP at 1 h, 1 day, 8 weeks and 6 months, and the rate of adverse ocular tissue reactions in all eyes.

RESULTS

Mean 1 ns and 3-5 ns SLT IOPs were 24.1 and 24.3 mmHg, respectively, at baseline. No statistically significant difference in mean 1 ns and 3-5 ns SLT IOP was observed at 1 h (P = 0.761), 1 day (P = 0.758), 8 weeks (P = 0.352) and 6 months postoperatively (P = 0.879). No significant difference in postoperative anterior chamber inflammation was observed between the eyes (P = 0.529). Treatment with both laser pulse durations resulted in minor ultrastructural changes in the drainage angle.

CONCLUSIONS

SLT performed with a 1 ns laser pulse duration does not appear to be inferior to SLT performed with the standard 3-5 ns duration at lowering IOP in treatment-naïve patients with POAG, NTG or OHT.

Selective Laser Trabeculoplasty Reduces Intraocular Pressure Peak in Response to the Water Drinking Test

PURPOSE

To determine the effect of selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) peak and fluctuation induced by the water drinking test (WDT) in patients with open-angle glaucoma and ocular hypertension.

METHODS

Patients with open-angle glaucoma or ocular hypertension underwent the WDT before and after SLT within a 12-month period. No other changes to therapeutic regimen were permitted. IOP was measured with a Goldmann applanation tonometer at baseline and every 15 minutes for 45 minutes following a fluid challenge of 800 mL over 15 minutes. Baseline, peak, and percentage fluctuation in IOP from baseline were compared using a repeated measures analysis of variance with Bonferroni adjustment.

RESULTS

Twenty eyes from 20 patients were included in this study. The median patient age was 73±15 years (interquartile range) and 70% of patients were female. Ten eyes (50%) had a diagnosis of primary open-angle glaucoma and 10 eyes had ocular hypertension. Following SLT there was a statistically significant reduction in mean baseline IOP from 16.9±2.4 to 14.2±2.3 mm Hg (P<0.001), peak IOP from 21.9±3.7 to 16.9±3.1 mm Hg (P<0.001).

CONCLUSIONS

Patients with open-angle glaucoma and ocular hypertension treated with SLT have significantly reduced peak IOPs and fluctuation in IOP in response to the WDT.

Intraocular Pressure-Lowering Potential of Subthreshold Selective Laser Trabeculoplasty in Patients with Primary Open-Angle Glaucoma

Purpose. To compare the efficacy of subthreshold and conventional selective laser trabeculoplasty (SLT) in lowering intraocular pressure (IOP) in the patients with primary open-angle glaucoma (POAG). Methods. Fifty-two eyes from fifty-two POAG patients were randomized into two groups, one group treated with subthreshold SLT using two-thirds of the conventional energy and the other one treated with the conventional energy. IOP was measured with the Goldmann tonometer and the anterior chamber inflammation was determined using laser flare meter. Results. The initial energy dosage used in subthreshold SLT group was significantly lower than the amount of the energy used in conventional SLT group (0.4 ± 0.1 mJ versus 0.6 ± 0.1 mJ, P = 0.030). The total energy dosage was also significantly lower in subthreshold SLT group compared to the other group (37.6 ± 3.3 mJ versus 51.8 ± 5.7 mJ, P = 0.036). However, the level of inflammation in aqueous humor, amount of reduction in IOP, and the success rate in controlling IOP was the same in both groups. Conclusion. The efficacy of subthreshold SLT group in reducing IOP in POAG patients is comparable to the efficacy of conventional SLT group.

Selective laser trabeculoplasty in patients with pseudoexfoliative glaucoma vs primary open angle glaucoma: a one-year comparative study

AIM

To compare the efficacy of single-session 360-degree selective laser trabeculoplasty (SLT) for reduction of intraocular pressure (IOP) in patients with pseudoexfoliative glaucoma (PXFG) and primary open angle glaucoma (POAG).

METHODS

This is a single-center, prospective, nonrandomized comparative study. Patients older than 18 years of age with uncontrolled PXFG or POAG eyes requiring additional therapy while on maximally tolerated IOP-lowering medications were included. The primary outcome measure changed in IOP from baseline. Success was defined as IOP reduction ≥20% from baseline without any additional IOP-lowering medication. All patients were examined at 1d, 1wk, 1, 3, 6, 9, 12mo after SLT.

RESULTS

Nineteen patients (20 eyes) with PXFG and 27 patients (28 eyes) with POAG were included in the study. In the visual fields mean deviation was -2.88 (±1.67) in the POAG and -3.1 (±1.69) in the PXFG groups (P=0.3). The mean (±SD) IOP was 22.9 (±3.7) mm Hg in the POAG group and 25.7 (±4.4) mm Hg in the PXFG group at baseline and decreased to 18.4 (±3.2) and 18.0 (±3.9) mm Hg in the POAG group (P<0.001 and P=0.02), and to 17.9 (±4.0) and 21.0 (±6.6) mm Hg in the PXFG group (P<0.001 and P=0.47) at 6 and 12mo, respectively. The number of medications was 2.6 (±0.8) in the POAG group and 2.5 (±0.8) in the PXFG group at baseline, and did not change at all follow-up visits in both groups (P=0.16 in POAG and 0.57 in PXFG). Based on Kaplan-Meier survival analysis, the success rate was 75% in the POAG group compared to 94.1% in the PXFG group (P=0.08; log rank test) at 6mo, and 29.1% and 25.0% at 12mo, respectively (P=0.9; log rank).

CONCLUSION

The 360-degree SLT is an effective and well-tolerated therapeutic modality in patients with POAG and PXFG by reducing IOP without any change in number of medications. The response was more pronounced early in the postoperative period in patients with PXFG whereas there was no statistically significant difference at 12-month follow-up.

Effect of selective laser trabeculoplasty on macular thickness

Background

To investigate the effects of selective laser trabeculoplasty (SLT) on macular thickness change.

Methods

Forty eyes of 40 consecutive patients with uncontrolled primary open-angle glaucoma with medical treatment were included in this prospective study. SLT was performed to the inferior 180°, and macular thickness was measured. Data were collected before SLT, and 1 week and 1 month after SLT. Macular thickness evaluation was performed in five quadrants, the central 1 mm quadrant (fovea = F), the nasal 3 mm quadrant surrounding F (NQ), temporal quadrant, superior quadrant (SQ), and inferior quadrant (IQ). The preoperative and postoperative thicknesses were compared.

Results

There was an increase in macular thickness in the NQ, IQ, and SQ on the first week after SLT compared to preoperative measurements. On the other hand, there was no significant increase in the F and temporal quadrant. On the first month after SLT, thickness in the NQ, IQ, and SQ was back to preoperative measurements, and there was no significant change between the preoperative measurements in any quadrant.

Conclusion

There was no significant increase in macular thickness shortly after SLT in our study.

Selective Laser Trabeculoplasty: An Update

Selective laser trabeculoplasty (SLT) is an effective treatment option for the reduction of intraocular pressure (IOP) in patients with ocular hypertension or open-angle glaucoma. The mechanism by which SLT lowers IOP is not completely understood and is likely multifactorial. Published studies indicate that SLT is at least as effective as argon laser trabeculoplasty or medications at lowering IOP in many forms of glaucoma. In addition to IOP reduction, SLT may decrease IOP fluctuation and can be successfully used as primary or adjunctive therapy for the management of both early and advanced glaucoma. However, SLT may not be effective in certain forms of glaucoma, and the IOP-lowering effect seems to wane with time. High pretreatment IOP is the strongest predictor of treatment success, even in patients with normal-tension glaucoma. Repeatability of SLT has been controversial, but recent evidence suggests that it can be successfully repeated to achieve additional or recurrent IOP reduction, even in eyes that only had a modest response to initial treatment. Adverse events are uncommon after SLT, and the most common complications such as discomfort and inflammation are typically mild and transient. Further investigation is required to determine the optimal treatment parameters for SLT treatment. Limited evidence suggests that SLT is cost-effective as primary therapy for patients with glaucoma.

Secretion of matrix metalloproteinase-3 by co-cultured pigmented and non-pigmented human trabecular meshwork cells following selective laser trabeculoplasty

BACKGROUND

Matrix metalloproteinases (MMPs) are reported to contribute to the mechanism of argon laser trabeculoplasty, but it is unknown whether they are also secreted after selective laser trabeculoplasty (SLT). The aim of this study was to investigate whether human primary trabecular meshwork (HTM) cells secrete MMP-3 after stimulation by SLT. The relationship between SLT and the two principal forms of cell death, apoptosis and necrosis, was also examined.

METHODS

Non-pigmented primary HTM cells were challenged with melanin granules to artificially introduce pigmentation. Isolated non-pigmented HTM cells and 1:1 co-cultures of pigmented and non-pigmented cells were treated with 0.5-1.5 mJ SLT. Cellular metabolic activity (CMA) was quantified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis and necrosis were measured using a cell death ELISA and a lactate dehydrogenase assay, respectively. MMP-3 secretion was measured by ELISA.

RESULTS

Co-cultures exhibited a dose-dependent decline in CMA and a dose-dependent increase in necrosis 4 and 24 h after SLT. Non-pigmented cells did not undergo necrosis and displayed a trend towards increased CMA. Apoptosis was reduced in non-pigmented cells but elevated in co-cultures. Increased MMP-3 secretion was observed from co-cultures but not isolated non-pigmented cells.

CONCLUSIONS

Pigmentation is necessary for both post-SLT cell death and MMP-3 secretion. SLT appears to have a hormetic effect on non-pigmented HTM cells.

Meta-analysis of selective laser trabeculoplasty versus topical medication in the treatment of open-angle glaucoma

Background

The aim of this study was to examine possible differences in clinical outcomes between selective laser trabeculoplasty (SLT) and topical medication in the treatment of open-angle glaucoma.

Methods

Pertinent prospective comparative controlled trials comparing SLT with medication were selected through extensive searches of the PubMed, Embase, Web of Science, Chinese Biomedicine Database, and the Cochrane Controlled Trials Register database from their inception up to March 2014. Efficacy estimates were measured by their weighted mean difference (WMD) to calculate the intraocular pressure reduction (IOPR) from baseline to endpoint and by the odds ratio (OR) to determine success rates.

Results

Five prospective studies, which met the predefined criteria, were included in the meta-analysis. Four studies were randomized clinical trials and one study was a prospective non-randomized clinical trial. There were a total of 492 eyes of 366 patients with open-angle glaucoma. Four studies involving 325 eyes compared SLT with medication in terms of the IOPR. The WMD of the IOPR from the baseline was 0.6 (95 % confidence intervals: −0.24,1.43) when comparing SLT with medication. No statistical heterogeneity was observed between studies (χ2 = 1.30, P = 0.75, I² = 0.0 %). All five studies reported success rates, with a pooled OR of 0.84 (95 % confidence intervals: 0.42, 1.68), which was not statistically significant. No statistical heterogeneity was observed between studies (χ2 = 5.98, P = 0.200, I² = 33.1 %). Subgroup and sensitivity analysis confirmed the high stability of the meta-analysis results.

Conclusions

Both SLT and topical medication demonstrate similar success rates and effectiveness in lowering intraocular pressure in patients with open-angle glaucoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-015-0091-2) contains supplementary material, which is available to authorized users.

Selective laser trabeculoplasty as a first-line therapy: a review

Poor adherence with glaucoma medications has been well documented. There remains a significant unmet need for a relatively safe intraocular pressure (IOP)-lowering procedure that minimizes or eliminates patient participation, and thus reduce the incidence of treatment failures attributable to nonadherence. Selective laser trabeculoplasty (SLT) offers several advantages: It effectively reduces IOP in most patients with open-angle glaucoma, it is cost-effective compared with eye drops, it can be repeated if needed, and it eliminates the issue of adherence to medications when used as an initial treatment. This article reviews the evidence supporting the use of SLT as a first-line therapy in glaucoma.