The hypotensive effect of selective laser trabeculoplasty depending on iridocorneal angle pigmentation in primary open angle glaucoma patients

Intraocular pressure profile following selective laser trabeculoplasty in pigmentary and primary open-angle glaucoma

PURPOSE

To compare the intraocular pressure (IOP) profile and the incidence of IOP spikes following selective laser trabeculoplasty (SLT) between pigmentary glaucoma (PG) and primary open-angle glaucoma (POAG).

MATERIALS AND METHODS

Retrospective comparative study of 65 PG eyes of 51 patients matched with 65 POAG eyes of 65 patients who received SLT. Matching was done based on age, gender, glaucoma severity, pre-laser IOP, and number of medications. Post-SLT IOP spike was defined as IOP elevation ≥5mmHg, 30-45 min after the laser.

RESULTS

In PG and POAG groups, the average age was 62.33 ± 9.18 and 62.58 ± 9.19 years (p = 0.95). The glaucoma severity (p = 0.708), baseline IOP (PG = 21.61 ± 1.34mmHg vs. POAG = 21.13 ± 5.09mmHg, p = 0.943), and number of topical glaucoma medications(PG = 2.34 ± 1.34 vs. POAG = 2.1 ± 1.41, p = 0.342) were comparable. More PG patients were on oral acetazolamide (PG = 26.15% vs. POAG = 1.5%, p < 0.001). Average logMAR visual acuity was significantly higher in the POAG group (0.207 ± 0.3 vs. 0.192 ± 0.37, p = 0.012). Eyes with PG received lower laser energy (POAG = 63.65 ± 22.03 mJ vs. PG = 43.71 ± 25.68 mJ, p < 0.001). IOP spikes were recorded in 5 PG eyes (7.6%) and none in the POAG group (p = 0.058). Failure rates were similar (PG = 50.7% and POAG = 43.1%, p = 0.205). In multivariable analysis, only pre-laser IOP (coefficient = 2.154 [CI: 0.765-3.543], p = 0.003) was a significant predictor of IOP change percentage after 12 months.

CONCLUSIONS

SLT was comparably effective in both PG and POAG. IOP spikes were observed only in the PG group, though the total laser energy was lower in this group compared with POAG.

Selective Laser Trabeculoplasty (SLT) for IOP Control in a Patient with Bilateral Acute Iris Transillumination (BAIT)

INTRODUCTION

Bilateral acute iris transillumination (BAIT) is a clinical condition characterized by acute bilateral loss of iris pigment epithelium and iris transillumination. Because of the similar presentation, it is commonly confused with anterior uveitis, making it an important differential diagnosis for this condition.

CASE DESCRIPTION

We report the case of a 60-year-old male patient who presented all the characteristics of BAIT after undergoing systemic treatment with moxifloxacin and that had the intraocular pressure (IOP) successfully controlled with selective laser trabeculoplasty (SLT).

CONCLUSION

SLT might be an effective therapeutic option and should be considered for the control of IOP in BAIT.

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.

Effect of Preoperative Trabecular Meshwork Pigmentation and Other Eye Characteristics on Outcomes of Combined Phacoemulsification/Minimally Invasive Glaucoma Surgery

PURPOSE

To investigate associations between pigmentation of the trabecular meshwork (PTM) and other preoperative eye characteristics and outcomes of minimally invasive glaucoma surgery combined with phacoemulsification (Phaco/MIGS).

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Academic glaucoma clinic patients with symptomatic cataract and glaucoma treated with combined Phaco/MIGS.

METHODS

Analyzing preoperative PTM, intraocular pressure (IOP), IOP-lowering medications and visual acuity (VA) data in relation to Phaco/MIGS outcomes.

MAIN OUTCOME MEASURES

Pigmentation of the trabecular meshwork and other preoperative eye characteristics in relation to Phaco/MIGS success defined as postoperative IOP between 5 and 21 mmHg and IOP reduction of ≥ 20% and/or a reduction of ≥ 1 IOP-medications compared to baseline, and final IOP, IOP-lowering medications and VA.

RESULTS

A total of 265 eyes (172 patients, mean age, 73.5 [standard deviation, 10.0], range 35-95 years, male 40.0%) were identified and categorized with high PTM (108 eyes, 40.8%) or low PTM (157 eyes, 59.2%). The high PTM group, compared with the low PTM group, demonstrated higher preoperative IOP (16.7 [standard error 0.4] vs. 15.2 [0.4] mmHg, P = 0.009), included more eyes with primary open-angle glaucoma (POAG, P = 0.03), fewer eyes with normal-tension glaucoma (NTG, P = 0.01), and fewer eyes with mild stage glaucoma (P = 0.001). Compared to baseline, final IOP decreased by 6.5 [2.4]% and 13.4 [3.0]% (P = 0.075) to 13.5 [0.3] mmHg and 13.6 [0.4] mmHg (P = 0.77) in the low and high PTM groups, respectively, and IOP-lowering medications decreased by 34.6 [4.9]% (n = 116) and 18.1 [7.3]% (n = 85), respectively (P = 0.062). Surgical success was 59.9% and 58.3%, respectively (P = 0.87). It was positively associated with higher preoperative IOP (hazard ratio 1.08 [95% confidence interval 1.04-1.12] P < 0.0001) and higher number of preoperative IOP-medications (1.20 [1.05-1.37] P = 0.007), negatively associated with history of selective laser trabeculoplasty (SLT, 0.40 [0.23-0.68] P = 0.0009) and longer axial length (0.87 [0.80-0.94], P = 0.0006), but was not associated with PTM.

CONCLUSIONS

Higher PTM was associated with POAG rather than NTG, with more severe glaucoma and higher preoperative IOP, but not with Phaco/MIGS success. Surgical success was positively associated with higher preoperative IOP and number of IOP-medications and negatively associated with history of SLT and longer axial length. These findings may help guide glaucoma surgeons in surgical planning and patient counseling.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Long-term follow-up of laser trabeculoplasty in multi-treated glaucoma patients

PURPOSE

To evaluate the long-term effect of laser trabeculoplasty (LTP) in patients randomized to multi-treatment in the Glaucoma Intensive Treatment Study (GITS).

METHODS

Patients with untreated newly diagnosed open-angle glaucoma were treated with three intraocular pressure (IOP)-lowering substances for 1 week and then 360° argon or selective LTP was performed. IOP was measured just before LTP and repeatedly during the 60-month study period. Our previous report on 12 months follow-up data revealed no effect of LTP in eyes having an IOP <15 mmHg before the laser treatment.

RESULTS

Before LTP, the mean IOP ± standard deviation in all 152 study-eyes of 122 multi-treated patients was 14.0 ± 3.5 mmHg. Three eyes of three deceased patients were lost to follow-up during the 60 months. After exclusion of eyes that received increased therapy during follow-up, the IOP was significantly reduced at all visits up to 48 months in eyes with pre-LTP IOP ≥15 mmHg; 2.6 ± 3.1 mmHg at 1 month and 1.7 ± 2.8 mmHg at 48 months, n = 56 and 48, respectively. No significant IOP reduction was seen in eyes with pre-LTP IOP <15 mmHg. Seven eyes, i.e., <13%, with pre-LTP IOP ≥15 mmHg at baseline had required increased IOP-lowering therapy at 48 months.

CONCLUSION

LTP performed in multi-treated patients may provide a useful IOP reduction that is maintained over several years. This was true on a group level when the initial IOP was ≥15 mmHg, but if the pre-laser IOP was lower than that, chances of LTP success were small.

Efficacy of Selective Laser Trabeculoplasty in Primary Angle-closure Glaucoma after Peripheral Iridotomy

Aim

To evaluate the efficacy of selective laser trabeculoplasty (SLT) in Southeast Asian eyes with primary open-angle glaucoma (POAG) vs primary angle-closure glaucoma after peripheral iridotomy (PACG-PI).

Materials and methods

Records of glaucoma patients who underwent SLT and had a 24-month follow-up were reviewed. Pre- and post-treatment intraocular pressure (IOP), percentage of IOP reduction in POAG, and PACG-PI groups, and probability of failure were analyzed. SLT failure was defined as any eye that did not have IOP lower than 20% compared to the baseline or had an IOP higher than the baseline on two consecutive visits. Adding medication, repeating SLT, or surgical intervention to control IOP was also considered a failure.

Results

Sixty-three POAG and 12 PACG-PI eyes were eligible. The mean (standard deviation [SD]) age was 62.9 (10.2) years in POAG and 60.3 (6.2) years in PACG-PI. Mean (SD) prelaser IOP in POAG was 19.0 (4.4) mm Hg and 20.7 (4.7) mm Hg in PACG-PI. At 24 months post-SLT, mean (SD) IOP was 14.1 (4.7) mm Hg and 13.6 (2.0) mm Hg in POAG and PACG-PI, respectively. There was no significant difference in percentage of IOP reduction (22.8 ± 23.0% for POAG and 30.7 ± 19.5% for PACG-PI, p = 0.96), or failure probability (p = 0.10) between both groups.

Conclusion

The efficacy of SLT at 24 months was comparable between POAG and PACG-PI.

Clinical significance

Selective laser trabeculoplasty may be an option to further lower IOP in eyes with angle closure with visible trabecular meshwork (TM) after iridotomy, especially in highly pigmented eyes of Southeast Asians.

How to cite this article

Wongwuticomjon T, Chansangpetch S, Inobhas A, et al. Efficacy of Selective Laser Trabeculoplasty in Primary Angle-closure Glaucoma after Peripheral Iridotomy. J Curr Glaucoma Pract 2022;16(2):124-127.

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.

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.

Real-world data from selective laser trabeculoplasty in Brazil

Evaluate real-world data of outcomes from selective laser trabeculoplasty (SLT) performed in different regions of Brazil and investigate potential predictors of success associated with treatment. Multicenter retrospective case series with patients who underwent a primary SLT procedure. A total of 835 eyes from 835 patients were included. The mean follow-up was 916.8 ± 563.0 days. The mean age was 64.5 ± 14.9 years and 56.6% were women. We observed an intraocular pressure reduction comparing baseline to post-SLT measurements (18.4 ± 3.8 mmHg versus 14.8 ± 3.5 mmHg; P < 0.001) and mean number of glaucoma medications (1.8 ± 1.3 versus 1.4 ± 1.4; P < 0.001). We observed visual acuity loss over time (0.1 ± 0.3 versus 0.2 ± 0.3 logMAR, baseline and post-SLT, respectively, P = 0.009) and decrease in visual field mean deviation values (- 5.4 ± 5.9 versus - 5.7 ± 6.0 dB; P = 0.054) The Kaplan-Meier survival analysis showed an estimated probability of treatment success of 88% at 12 months, declining to 70% at 24 months and 54% at 36 months post-SLT. In the multivariable model, we found that a denser angle pigmentation (HR 0.69; 95% CI 0.57-0.85, P = 0.001) and corticosteroid treatment following SLT (HR 0.59; 95% CI 0.39-0.91, P = 0.018) were significantly associated with a lower risk for failure. Primary SLT achieved relatively high success rates without sight-threating complications in this real-world study with a large sample of Brazilian patients. These findings corroborate previous studies regarding SLT outcomes and may help clinicians to identify the best candidates for laser treatment.

[Pigmentary glaucoma: yesterday, today, tomorrow]

Pigment dispersion syndrome (PDS) is a condition that mostly affects young men with myopic refraction. PDS is characterized by the presence of Krukenberg spindle, peripheral iris defects, significant trabecular meshwork pigmentation, as well as convex iris configuration. Such configuration can cause friction of iris's posterior pigment layer on its ligaments, which leads to the release of pigment and its accumulation mostly in the structures of the anterior chamber. Over time PDS can progress into pigmentary glaucoma (PG), which in turn can lead to permanent loss of vision. This review analyzes available data on diagnosis and treatment of PDS and PG.

Selective laser trabeculoplasty: A review

Glaucoma is the second most prevalent cause of blindness worldwide, and the only effective management is the lowering of intraocular pressure (IOP). Selective laser trabeculoplasty (SLT) has become an essential part of glaucoma management since its commercial release in 2001. It has been an improvement from the previous argon laser trabeculoplasty (ALT), by using 1% of the laser energy, reducing the amount of anterior segment inflammation and minimising the degree of mechanical injury to the trabecular meshwork. There is now a large volume of work that demonstrates SLT is equally effective as ALT and topical medication in lowering IOP. It is simple to perform, with a well described side-effect profile, and is long-lasting and repeatable. This review will summarise the current literature on SLT for each of these topics.

[Experience of combined laser treatment for pigmentary glaucoma]

PURPOSE

To analyze the results of combined laser treatment for pigmentary glaucoma using laser iridectomy (LIE) and selective laser trabeculoplasty (SLT).

MATERIAL AND METHODS

The two-stage laser treatment was performed in 12 patients (22 eyes) with pigmentary glaucoma (primary stage - 19 eyes, advanced - 3 eyes). The first stage consisted of LIE; after 5.5±2.2 months, second stage in the form of SLT took place. The follow-up was 16.8±3.2 months.

RESULTS

In the early post-op period after LIE, P₀ decreased to 14.76±0.72 mm Hg, however the intraocular pressure (IOP) gradually increased during the further follow-up. After SLT, a steady P₀ decrease to 12.39±0.66 mm Hg was reached - significantly lower in comparison with the initial data (19.94±0.94 mm Hg). Moreover, significant decrease in the number of hypotensive medications used was noted by the end of the follow-up - from 1.73±0.18 to 0.86±0.15.

CONCLUSION

The combined laser treatment involving LIE and SLT was effective in treating primary and advanced pigmentary glaucoma.

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: 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.

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.