Endothelin-1 increase in aqueous humour caused by frequency-doubled Nd:YAG laser trabeculoplasty in rabbits

Efficacy of Selective Laser Trabeculoplasty in Patients on Systemic Immunosuppressive Therapy

PRCIS

When comparing patients on systemic immunosuppressive therapy to those without, there was no difference in intraocular pressure (IOP) early after SLT; however, at 1 year following SLT, IOP was higher in the immunosuppression group compared with controls.

PURPOSE

To determine whether patients taking systemic immunosuppressive medications have a different IOP-lowering response to selective laser trabeculoplasty (SLT) compared with a control group of patients.

METHODS

All patients who underwent SLT at Mayo Clinic 2017-2021 were identified. Patients on systemic immunosuppressive medications at the time of SLT were compared with control patients not receiving systemic immunosuppressive medications. The primary endpoints of this study were the percentage IOP reduction at 1 to 2, 3 to 6, and 12 months. Additional analyses included the percentage of patients who did not require additional therapy at each time point.

RESULTS

There were 108 eyes of 72 patients that underwent SLT in the immunosuppressed group and 1997 eyes of 1417 patients in the control group. There was no significant difference in age-adjusted change in IOP between groups at the first postoperative visit 1 to 2 months following SLT (-18.8±20.7% vs. -16.0±16.5%, P =0.256) or 3-6 months following SLT (-15.2±21.6% vs. -18.3±23.2%, P =0.062). However, at 12 months following SLT, the IOP reduction in the immunosuppressive therapy group was significantly less compared with the control group (-15.1±21.2% vs. -20.3±22.9%, P =0.045). There was no difference between groups in the number of additional treatments during the study intervals.

CONCLUSION

Patients in the systemic immunosuppressive therapy group showed equivalent early IOP-lowering after SLT compared with a control group, but the treatment response was diminished at 1 year. Further studies investigating IOP regulation after SLT in immunosuppressed patients are needed.

Impact of Short-Term Topical Steroid Therapy on Selective Laser Trabeculoplasty Efficacy

Background: To evaluate whether short-term use of topical steroid therapy affected the efficacy of selective laser trabeculoplasty (SLT) for primary open-glaucoma (POAG). Methods: 25 eyes of 25 patients, who used a drop of dexamethasone 0.1% 4 times a day for 7 days as post-laser therapy, formed the Steroid SLT group and 24 eyes of 24 patients, where no topical steroids or nonsteroidal anti-inflammatory agents as post-laser therapy were used, formed the No-steroid SLT group. Success was defined as an intraocular pressure (IOP) lowering exceeding 20% of pretreatment IOP. Results: The mean follow-up time was 21.24 months for the Steroid SLT group and 20.25 months for the No-steroid SLT group (p = 0.990). No significant difference was found between the two groups for mean pretreatment IOP (22.20 mmHg vs. 22.33 mmHg), and for mean IOP reductions during whole follow-up period. At all follow-up visits, the mean IOP reductions were smaller in the Steroid SLT group than in the No-steroid SLT group. At all follow-up visits, the mean percent IOP reduction was smaller in the Steroid SLT group than in the No-steroid SLT group, and such a difference was significant at 12 months (25.4% vs. 29.6%, p = 0.047) and 24 months (25.3% vs. 29.7%, p = 0.024). According to the Kaplan–Meier survival analysis, the 24-month success rate was 84% in the Steroid SLT group and 79.2% in the No-steroid SLT group, with no differences between the groups (p = 0.675). Conclusion: Short-term use of topical steroid therapy had no impact on the efficacy of SLT for POAG.

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.

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.

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.

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.

Twenty-four-hour intraocular pressure related changes following adjuvant selective laser trabeculoplasty for normal tension glaucoma

To investigate intraocular pressure (IOP) related patterns before and after selective laser trabeculoplasty (SLT) for normal tension glaucoma (NTG).In this prospective cohort study, 18 NTG patients underwent SLT. Success was defined as IOP reduction ≥ 20% by Goldmann applanation tonometry. 24-hour IOP-related pattern recording with a contact lens sensor (CLS) (SENSIMED Triggerfish, Sensimed, Switzerland) was done before (baseline) and 1 month after SLT. A cosine function was fitted to the mean CLS patterns for each individual in the SLT success and non-success groups and the amplitude before and after SLT was calculated. Diurnal, nocturnal, and 24-hour CLS pattern local variability was determined for pre- and post-SLT sessions. Cosine amplitude and variability were compared before and after SLT by group using paired t-tests, with α = 0.05. Patients (11 women, 7 men) had a mean age of 65.1 ± 13.7 years. Mean IOP was 15.3 ± 2.2 mm Hg at baseline and was reduced by 17.0% to 12.7 ± 1.8 mm Hg 1 month after SLT (P = 0.001). SLT was successful in 8 patients (44%). The amplitude of the fitted cosine was reduced by 24.6% in the success group, but displayed an amplitude increase of 19.2% post-SLT in the non-success group. Higher diurnal local variability of the CLS pattern was observed after SLT in non-success subjects (P = 0.002), while nocturnal variability showed no significant change. The increase in diurnal variability in the non-success group led to an increase in 24-hour variability in this group (P = 0.001). No change in local variability (diurnal, nocturnal, and 24-hour) was seen in the success group. The IOP-related pattern cosinor amplitude was reduced in NTG patients with a successful SLT treatment whereas the non-success group exhibited an increase of cosine amplitude. Higher diurnal and 24-hour CLS pattern variability was observed in non-success patients 1 month post-SLT.

Mechanisms of selective laser trabeculoplasty: a review

Selective laser trabeculoplasty is a safe and effective treatment for glaucoma, with greater cost effectiveness than its pharmacological and surgical alternatives. Nevertheless, although the basic science literature on selective laser trabeculoplasty continues to grow, there remains uncertainty over the mechanism by which laser trabeculoplasty reduces intraocular pressure. To address this uncertainty, the evidence behind several potential biological and mechanical mechanisms of selective laser trabeculoplasty were reviewed. In particular, cytokine secretion, matrix metalloproteinase induction, increased cell division, repopulation of burn sites and macrophage recruitment were discussed. Refining our understanding of these mechanisms is essential both to understanding the pathophysiology of ocular hypertension and developing improved therapies to treat the condition.

Regulation of trabecular meshwork cell contraction and intraocular pressure by miR-200c

Lowering intraocular pressure (IOP) delays or prevents the loss of vision in primary open-angle glaucoma (POAG) patients with high IOP and in those with normal tension glaucoma showing progression. Abundant evidence demonstrates that inhibition of contractile machinery of the trabecular meshwork cells is an effective method to lower IOP. However, the mechanisms involved in the regulation of trabecular contraction are not well understood. Although microRNAs have been shown to play important roles in the regulation of multiple cellular functions, little is known about their potential involvement in the regulation of IOP. Here, we showed that miR-200c is a direct postranscriptional inhibitor of genes relevant to the physiologic regulation of TM cell contraction including the validated targets Zinc finger E-box binding homeobox 1 and 2 (ZEB1 and ZEB2), and formin homology 2 domain containing 1 (FHOD1), as well as three novel targets: lysophosphatidic acid receptor 1 (LPAR1/EDG2), endothelin A receptor (ETAR), and RhoA kinase (RHOA). Consistently, transfection of TM cells with miR-200c resulted in strong inhibition of contraction in collagen populated gels as well as decreased cell traction forces exerted by individual TM cells. Finally, delivery of miR-200c to the anterior chamber of living rat eyes resulted in a significant decrease in IOP, while inhibition of miR-200c using an adenoviral vector expressing a molecular sponge led to a significant increase in IOP. These results demonstrate for the first time the ability of a miRNA to regulate trabecular contraction and modulate IOP in vivo, making miR-200c a worthy candidate for exploring ways to alter trabecular contractility with therapeutic purposes in glaucoma.

Endothelin-1 concentration is increased in the aqueous humour of patients with exfoliation syndrome

BACKGROUND

/aim: Endothelin 1 (ET-1) is considered the most potent vasoconstrictor in the body and the eye. This molecule may play a significant role in the pathobiology of exfoliation syndrome (XFS), a disorder characterised by a progressive iris vasculopathy. The purpose of this study was to investigate the concentration of ET-1 in the aqueous humour of cataract patients with and without XFS.

METHODS

Aqueous humour samples were obtained from 25 consecutive eyes of 25 cataract patients with XFS and an equal number of age matched controls during phacoemulsification cataract surgery. None of the subjects had elevated intraocular pressure or glaucoma. ET-1 concentration in the aqueous was measured using a specific immunoassay with 100% immunoreactivity for ET-1. Total aqueous humour protein concentration was measured with a microplate Coomassie blue based method and was correlated with ET-1 concentration.

RESULTS

Mean ET-1 concentration in the XFS aqueous samples (4.6 (SD 2.3) pg/ml) was significantly higher than that measured in the age matched control samples (2.8 (SD 1.71) pg/ml); (p = 0.006). Although total protein concentration was significantly elevated in the XFS samples (0.380 (SD 0.159) v 0.279 (SD 0.144) mg/ml in the controls); (p = 0.023), no correlation was found between aqueous ET-1 and total protein concentration (p = 0.730).

CONCLUSION

The increased concentration of ET-1 in the aqueous humour of XFS patients suggests that ET-1 may play a role in the pathobiology of XFS.