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.

Comparison of success rate and intraocular pressure spikes between selective laser trabeculoplasty and micropulse laser trabeculoplasty in African American and Hispanic patients

AIM:To examine the efficacy and safety of micropulse laser trabeculoplasty(MLT)versus selective laser trabeculoplasty(SLT)in a large cohort of primarily African American and Hispanic patients.METHODS:A single center retrospective comparative cohort review conducted at Cook County Health facilities that included patients with a diagnosis of open angle glaucoma or ocular hypertension who received an SLT or MLT procedure between January 2017 and May 2021.RESULTS:Totally 131 eyes of 99 patients were analyzed.The 77 eyes received SLT and 54 received MLT.Seven out of 77 eyes in the SLT group(9.1%)and 1 out of 54 eyes in the MLT group(1.9%)had an IOP spike(defined as>5 mm Hg)at either 1h or 1wk after procedure(P=0.05,Chisquared test with Haldane-Anscombe correction).The procedure failure rate at one year was 50%for SLT and 48%for MLT(P=0.31).CONCLUSION:MLT has a significantly lower incidence of pressure spikes and a similar treatment failure rate at 1-year post-procedure,demonstrating that it is a reasonable alternative compared to SLT.

Selective laser trabeculoplasty as adjunctive treatment for open-angle glaucoma vs following incisional glaucoma surgery in Chinese eyes

BACKGROUND Selective laser trabeculoplasty(SLT)is a relatively safe and effective therapy in lowering intraocular pressures(IOP)for glaucoma.AIM To study the long-term effects of SLT on IOP and number of glaucoma medications used in Chinese eyes.METHODS This is a retrospective study in which 75 eyes of 70 patients with open-angle glaucoma(OAG,n=36)and eyes with prior glaucoma surgery(PGS,n=39)were included.Changes in mean IOP and number of glaucoma medications used evaluated at 1 d,1 wk,1 mo,3 mo,6 mo,12 mo,and 36 mo after laser treatment.RESULTS All patients(33 male,37 female)were Chinese.The mean age was 44.34±16.14years.Mean pre-SLT IOP was 22.75±2.08 mmHg in OAG and 22.52±2.62 mmHg in PGS.Mean IOP was significantly reduced 1 d,1 wk,1 mo and 3 mo after laser treatment(P<0.05,respectively).Whereas,there were no significant differences between baseline and SLT treated groups at the 6th month both in OAG(P=0.347,P>0.05)and in PGS(P=0.309,P>0.05).Six months after SLT treatment,some patients received retreatment of SLT or were given more topical IOP-lowering medication to control the IOP.By the end of our study,the average IOP decreased to 20.73±1.82 mmHg in OAG and 20.49±1.53 mmHg in PGS groups.The number of glaucoma medications used was significantly reduced until the end of 3 years compared to baseline.CONCLUSION SLT could reduce IOP as adjunctive treatment both in OAG and PGS groups.SLT significantly reduced the number of glaucoma medications used 3-years following treatment in glaucoma patients.

Selective laser trabeculoplasty in pseudophakic and phakic eyes:a prospective study

AIM：To compare the efficacy of selective laser trabeculoplasty（SLT） in replacing medical therapy in pseudophakic and phakic eyes.METHODS：Subgroup of a prospective randomized clinical trial including patients with primary open angle glaucoma or ocular hypertension controlled with medication.Of 38 pseudophakic eyes were matched with 38 phakic eyes.SLT was offered as a way to decrease medication while maintaining the same low eye pressure.SLT was performed over 360°,at 3ns,spotsize 400 μm,100 spots.Data [intraocular pressure（IOP）,number of medications needed] were measured at 1h,1wk,1,3,6 and 12 mo.An independent-samples t-test was performed to compare baseline characteristics of the phakic and the pseudophakic group and differences in evolution of mean IOP and number of used medications.Chi-squared analysis was performed to investigate proportions of fast,slow and non-responders.RESULTS：The mean IOP measurement was 13.00± 2.88 mm Hg in the phakic group（38 eyes） and 13.51±3.06 mm Hg in the pseudophakic group（38 eyes）（P〉0.05）.This changed little after SLT and IOP lowering effect was comparable between the two groups.Main aim however was to lower the amount of medication needed.In the phakic group medication lowered from 1.29±0.62 at baseline,to 0.15±0.46 after 12mo;a reduction of 88.37%.In the pseudophakic group,used medication changed from 1.71±1.04,to 0.41±0.61;a 76.02% reduction.The differences were not statistically significant at any time point（P〉0.05）.IOP lowering occurred slightly faster in thepseudophakic group（50% of patients after one week） than in the phakic group（68% of patients after more than 4wk）.The difference was not significant（P〉0.05）.CONCLUSION：IOP lowering effect of SLT is comparable between phakic and pseudophakic eyes.

Selective laser trabeculoplasty

The introduction of selective laser trabeculoplasty (SLT) provided a new choice for the reduction of intraocular pressure (IOP) in eyes with open angle glaucoma (OAG) and ocular hypertension (OHT). SLT was demonstrated equally as effective as topical medical therapy and argon laser trabeculoplasty (ALT) to lower IOP. It is a potentially repeatable procedure because of the lack of coagulation damage to the trabecular meshwork (TM) and also effect in patients with previously failed ALT. SLT can be used to treat patients with OAG, pseudoexfoliation glaucoma, pigmentary glaucoma, normal-tension glaucoma, OHT, juvenile glaucoma, pseudophakic and aphakic glaucoma. Furthermore, SLT can be considered as a primary treatment option in patients who cannot tolerate or are noncompliant with medications, while not interfering with the success of future surgery. Its safety profiles include mild and transient inflammation, ocular pain and a small risk of moderate IOP elevations after the procedure. SLT is a safe and effective means of IOP reduction in eyes with OAG and OHT.

Efficacy and safety of micropulse laser trabeculoplasty for primary open angle glaucoma

AIM: To evaluate the efficiency and safety of micropulse laser trabeculoplasty(MLT) for primary open angle glaucoma(POAG) patients. METHODS: Retrospective study. POAG patients undergoing MLT in Peking University Third Hospital from June 2016 to November 2017. Seventy-two eyes of 72 POAG patients were enrolled. Only one eye of each patient was treated by MLT. The intraocular pressure(IOP) before MLT and at 1 d, 1, 4, 12 and 24 wk and glaucoma medication before and after treatment were compared.RESULTS: The IOP was 20.6±5.9 mm Hg before MLT and 20.8±6.8 mm Hg at 2 h after MTL. The IOP at 1 d, 1, 4, 12 and 24 wk was 17.9±4.4, 18.0±4.3, 17.5±3.4, 17.0±2.7, and 16.5±2.9 mm Hg, respectively. The IOP before and after MLT demonstrated a statistically significant difference by ANOVA analyses(F=5.797, P<0.001). Least significant difference t-tests showed there was no statistically significant difference between pre-MLT IOP within 2 h after MLT(P=0.207). The statistically significant difference was confirmed between the pre-MLT IOP at 1 d, 1, 4, 12 and 24 wk after MLT(P=0.006, 0.009, 0.001, <0.001, <0.001, respectively). The number of glaucoma medications before MLT was 1.7±1.4 and 1.5±1.4 24 wk after MLT with a significantly statistical difference(t=2.219, P=0.031)CONCLUSION: MLT is effective and safe for POAG patients. No patient experienced IOP spikes after MLT. The IOP 6 mo after treatment decreased significantly with less glaucoma medication.

Efficacy of low-energy selective laser trabeculoplasty on the treatment of primary open angle glaucoma

AIM: To investigate the efficacy of low-energy selective laser trabeculoplasty(SLT) on the treatment of primary open angle glaucoma(POAG) patients.METHODS: Outpatients with POAG who underwent 360-degree SLT using an initial energy of 0.3 mJ(total energy of 30-40 mJ) were reviewed retrospectively from September 2011 to January 2018.RESULTS: Eight-six eyes of 44 POAG patients underwent 360-degree SLT using initial energy of 0.3 mJ and were followed up regularly. The total energy used was 32.5±2.5 mJ(23-40 mJ, 105±6 spots). The average pretreatment intraocular pressure(IOP) was 19.8±3.9 mm Hg. At 1, 3, 6 mo, 1, and 2 y, the post-SLT IOPs(mm Hg) were 16.9±3.3, 16.5±3.3, 17.1±3.4, 16.6±3.5, 16.5±2.8, which were significantly lower than that before treatment(P<0.001). The patients in the SLT success group were found to be younger than those in the SLT failure group. After SLT, 59 eyes that maintained pretreatment medications were defined as the drug retention group. The pre-SLT IOP was 20.1±3.7 mm Hg.At 1, 3, 6 mo, 1, and 2 y, the post-SLT IOPs(mm Hg) were 17.3±3.6, 16.6±3.5, 17.2±3.6, 16.9±3.8 and 16.5±2.9, respectively. Twenty-seven eyes that required reduced drugs were defined as the drug reduction group. The pre-SLT IOP was 19.2±4.4 mm Hg. At 1, 3, 6 mo, 1, and 2 y, the post-SLT IOPs(mm Hg) were 16.1±2.6, 16.5±3.1, 16.8±2.9, 16.0±2.6 and 16.3±2.4, respectively. Compared with the pretreatment IOPs, the post-SLT IOPs were significantly lower in drug retention group and drug reduction group. The patients in the drug reduction group were found to be younger than those in the drug retention group.CONCLUSION: Low-energy SLT is safe and effective for POAG patients during a 2-year follow-up. Younger POAG patients may obtain better results after low-energy SLT treatment.

Efficacy of selective laser trabeculoplasty following incisional glaucoma surgery

AIM： To evaluate the efficacy of selective laser trabeculoplasty（SLT） in glaucomatous eyes with previous incisional glaucoma surgery. METHODS： A retrospective cohort of eyes that underwent SLT at a single institution from 2013-2015 were followed for 1 y. Reduction in intraocular pressure（IOP） following SLT was evaluated in eyes with prior trabeculectomy with Ex Press mini shunt（Alcon, Ft Worth, TX, USA）, Ahmed valve（New World Medical, Cucamonga, CA, USA）, or combined phacoemulsification-trabeculectomy. A control group was included with eyes without prior surgery that underwent SLT. Success was defined as 〉20% drop in IOP from pre-SLT baseline. RESULTS： One-hundred and six eyes were included with 53 in both the prior glaucoma surgery（PGS） and no prior glaucoma surgery（NPGS） groups. Mean pre-SLT IOP was 19.2±4.3 and 20.6±6.0 mm Hg for PGS and NPGS groups, respectively（P=0.17）. Both groups produced statistically significant IOP reductions at 1 and 6 mo（P〈0.04）. At 6 mo, mean IOP reduction reached 7.3% and 10.8% for the PGS and NPGS groups, respectively（P=0.42）. Overall, 27.9% and 31.7% of eyes in PGS and NPGS groups met success criteria at 1 y（P=0.70）. In the PGS group, eyes with baseline IOP ≥21 mm Hg had IOP reductions of 18.1%（P〈0.001）, 16.7%（P〈0.01）, and 8.4%（P=0.31） compared to eyes with baseline IOP 〈21 mm Hg who had IOP reductions of 2.3%（P=0.39）, 3.4%（P=0.19）, and 1.1%（P=0.72） at 1, 6 mo, and 1 y, respectively. CONCLUSION： SLT is efficacious in eyes with prior incisional glaucoma surgery and results in similar IOP reductions compared to eyes without PGS. A larger IOP reduction is observed following SLT in eyes with higher pre-SLT IOP.

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,1,3,6,9,12 mo after SLT.· RESULTS：Nineteen patients（20 eyes） with PXFG and27 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 12 mo,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 12 mo,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. 〈/tr〉

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 6 mo,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 6 mo,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 6 mo,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.

Clinical outcomes of patterned laser trabeculoplasty as adjuvant therapy in open angle glaucoma and ocular hypertension

AIM： To assess the efficacy and safety of patterned laser trabeculoplasty（PLT） as an adjunctive treatment in open angle glaucoma（OAG） or ocular hypertension（OHT） patients who were under antiglaucoma medical treatment.METHODS： This study was a retrospective review of primary or secondary OAG patients and OHT patients with medically uncontrolled（≥18 mm Hg） intraocular pressure（IOP） who underwent 360o PLT from June 2016 to August 2016. Follow-up visits at week 1, and 1, 3 and 6 mo were performed. IOP, best corrected visual acuity（BCVA）, complications and eye drop glaucoma medication were recorded at each follow-up visit. Success was defined as IOP reduction ≥20% from baseline. RESULTS： Forty-one eyes of 25 patients were included in this study. Pre-treatment mean IOP was 20.2±1.6 mm Hg. After PLT, IOP was 19.3±5.2, 16.1±2.7, 17.1±3.7 and 16.3±3.5 mm Hg,at 1 wk, 1, 3 and 6 mo, respectively. IOP reduction from baseline was statistically significant from the first month, remaining stable at 6 mo（P〈0.001）. PLT success at 6 mo of follow-up was 48.78%. The number of glaucoma medication per eye（P=0.10） and the mean BCVA both remained constant（P=0.37）. Complications included transient IOP spikes in 4 eyes（9.8%） and peripheral anterior synechiae in 7 eyes（17.1%）. CONCLUSION： PLT is an effective and safe method for the management of patients with OHT or OAG as an adjunctive therapy. Additional larger studies should be designed to verify the long-term stability of IOP reduction with this laser technology.

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

AIMTo determine the long-term effects of selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) and the number of medications used up to 5y following treatment in glaucoma patients receiving maximally tolerated medical therapy (MTMT).METHODSThe Wills Eye Hospital Glaucoma Research Center retrospectively reviewed the charts of glaucoma patients who underwent SLT after receiving MTMT. Eyes that did not achieve their target pressure within 3mo following SLT were excluded from the study. Changes in mean IOP and number of glaucoma medications used were analyzed at 1, 3, and 5y following SLT.RESULTSSeventy-five eyes of 67 patients were included in the study. Fifteen eyes that received SLT failed to achieve their target pressure within 3mo and were excluded from the study. The average follow-up time was 37.4mo (&#x000b1;14.4). Mean IOP was significantly reduced 1y after treatment (P=0.005). It was also reduced 3, 5y after treatment without reaching statistical significance (P=0.20 and P=0.072, respectively). There was a significant decrease in mean number of medications used 1, 3, 5y after treatment (P&#x0003c;0.001, P&#x0003c;0.001, and P=0.039, respectively). In the span of 5y, 2 eyes (2.7%) underwent repeat SLT, 7 eyes (9.3%) underwent glaucoma surgery and an additional 3 eyes (4.0%) underwent both.CONCLUSIONSLT significantly reduced the number of glaucoma medications used 5y following treatment in glaucoma patients receiving MTMT. SLT may delay operating-room surgery.

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 18 mo 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±7.3 y).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.

Effects of primary selective laser trabeculoplasty on anterior segment parameters

AIMTo investigate the effects of selective laser trabeculoplasty (SLT) on the main numerical parameters of anterior segment with Pentacam rotating Scheimpflug camera in patients with ocular hypertension (OHT) and primary open angle glaucoma (POAG).METHODSPentacam measurements of 45 eyes of 25 (15 females and 10 males) patients (12 with OHT, 13 with POAG) before and after SLT were obtained. Measurements were taken before and 1 and 3mo after SLT. Pentacam parameters were compared between OHT and POAG patients, and age groups (60y and older, and younger than 60y).RESULTSThe mean age of the patients was 57.8±13.9 (range 20-77y). Twelve patients (48%) were younger than 60y, while 13 patients (52%) were 60y and older. Measurements of pre-SLT and post-SLT 1mo were significantly different for the parameters of central corneal thickness (CCT) and anterior chamber volume (ACV) (P<0.05). These parameters returned back to pre-SLT values at post-SLT 3mo. Decrease of ACV at post-SLT 1mo was significantly higher in younger than 60y group than 60y and older group. There was no statistically significant difference in Pentacam parameters between OHT and POAG patients at pre- and post-treatment measurements (P>0.05).CONCLUSIONSLT leads to significant increase in CCT and decrease in ACV at the 1st month of the procedure. Effects of SLT on these anterior segment parameters, especially for CCT that interferes IOP measurement, should be considered to ensure accurate clinical interpretation.

Selective laser trabeculoplasty:a review of repeatability

The efficacy of selective laser trabeculoplasty(SLT)to treat open-angle glaucoma(OAG)and ocular hypertension(OHT)has been increasingly substantiated lately.Repeated SLT is usually needed to control intraocular pressure(IOP),be it as primary or adjunctive therapy.We review the studies available,in terms of SLT repeatability;and conclude comparable efficacy,with success rate,duration and complications similar to those in initial SLT.

Where does selective laser trabeculoplasty stand now? A review

Background:Chronic treatment of glaucoma can present a challenge in patients who lack the means and/or the discipline to use daily glaucoma medication.We wondered if selective laser trabeculoplasty(SLT)could be a useful alternative.Methods:Inclusion criteria:controlled trials comparing efficacy of SLT in adult patients with any form of open angle glaucoma or ocular hypertension and case reports on side effects of SLT.Two recent meta-analyses identified eight randomized clinical trials(RCTs)comparing the effect of SLT with medication(prostaglandin analogs)and with argon laser trabeculoplasty(ALT).We took these eight RCTs as reference base and calculated their success rates where they were not given.Other articles were added to elaborate on technique and side effects.Results:Mean intraocular pressure(IOP)reduction after SLT was 3.8–8.0 mmHg after 6 months to 1 year.Mean success rate of SLT at 6 months to 1 year is 55–82%.Higher IOP before laser predicts a higher IOP-lowering effect.In terms of mean IOP reduction,reduction in number of medications and treatment success,the effect of SLT was found to show no clinically relevant difference from that of contemporary medication(prostaglandin analogs)and from ALT.Conclusions:The evidence indicates that SLT is an efficacious primary or adjunctive therapy for treating glaucoma.

Management of glaucoma in pregnancy:risks or choices,a dilemma?

The treatment of glaucoma in and around pregnancy offers the unique challenge of balancing the risk of vision loss to the mother as against the potential harm to the fetus or newborn. Most anti-glaucoma drugs（i.e.beta-blockers, prostaglandin analogues, carbonic anhydrase inhibitors topical and systemic, cholinergics,anticholinesterases, and apraclonidine） are considered category C agents and ophthalmologists are usually limited to treating patients with the category B drugs of brimonidine and dipivefrin. Brimonidine is generally the preferred first-line drug in the first, second and early third trimester. Late in the third trimester, brimonidine should be discontinued because it can induce central nervous system depression in newborns wherein topical carbonic anhydrase inhibitors may be the optimal choice.Glaucoma surgery can be performed with caution in second and third trimester if the patients have a strong indication for the procedure. However, anesthetics,sedative agents, and antimetabolites still have potential risk for the fetus. Argon laser trabeculoplasty（ALT） or selective laser trabeculoplasty（SLT） is an alternative treatment that can be performed in all trimesters.Carbonic anhydrase inhibitors and β-blockers are certified by the American Academy of Pediatrics for use during nursing. However, low doses of these medications should be considered when used in the breast feeding period. Optimum treatment for glaucoma in pregnancy must not be withheld so as to prevent any further deterioration in progressive vision loss and quality of life.

Current systems and recent developments of subthreshold laser systems in glaucoma:a narrative review

Background and Objective:Subthreshold laser technologies and their applications in ophthalmology have greatly expanded in the past few decades.Initially used for retinal diseases such as central serous chorioretinopathy and diabetic macular edema,subthreshold lasers have recently shown efficacy in the treatment of various types of glaucoma.Our primary objectives are to review the clinical applications of subthreshold laser in the context of glaucoma treatment and discuss the mechanisms of different subthreshold laser techniques,including subthreshold selective laser trabeculoplasty(SSLT),micropulse laser trabeculoplasty(MLT),pattern-scanning laser trabeculoplasty(PSLT),titanium laser trabeculoplasty(TLT),and micropulse transscleral cyclophotocoagulation(MP-TSCPC).Methods:This was a narrative review compiled from literature of PubMed and Google Scholar.The review was performed from March 2021 to October 2021 and included publications in English.We also included information from web pages to cover details of relevant laser systems.We discuss the history of subthreshold laser,recent advancements in subthreshold techniques,and commercially available systems that provide subthreshold capabilities for glaucoma.We highlight basic science and clinical studies that deepen the understanding of treatment mechanisms and treatment effectiveness in the clinical setting respectively.We review commonly used parameters for each technique and provide comparisons to conventional treatments.Key Content and Findings:We found five distinct types of subthreshold laser used in the management of glaucoma.Numerous subthreshold laser systems are commercially available and can provide this treatment.Therefore,understanding the differences between subthreshold techniques and laser systems will be critical in utilizing subthreshold laser in the clinical setting.Conclusions:Traditional laser trabeculoplasty(LT)and cyclophotocoagulation(CPC)have shown effectiveness in the treatment of various types of glaucoma but are associated with visible damage to the underlying tissue and adverse effects.Subthreshold laser systems aim to provide the therapeutic effect found in traditional lasers,while minimizing unwanted treatment related effects.Further clinical studies are needed to evaluate the role of subthreshold lasers in the management of glaucoma.