Hydrothermal pretreatment of press mud: Characterization and potential application of hydrochar and process water.

In the present study, press mud (PM), a major waste by-product from sugar industries, was subjected to hydrothermal pretreatment (HTP) to create resource recovery opportunities. The HTP process was performed with the PM samples in a laboratory scale high pressure batch reactor (capacity = 0.7 L) at 160 °C and 200 °C temperatures (solids content = 5 % and 30 %). The pretreatment resulted in separation of solid and liquid phases which are termed as solid hydrochar (HC) and process water (PW), respectively. High heating value (HHV) of HC was âˆ¼14-18 MJ kg-1, slightly higher than that of PM (14 MJ kg-1). The thermogravimetric analysis showed about 1.5-1.7 times higher heat release from HC burning compared to that observed from combustion of PM. Apart from this, the HC and PM showed no phytotoxicity during germination of mung bean (Vigna radiata). Moreover, the biochemical methane potential test on the PW showed a generation of 167-245 mL biogas per gram of chemical oxygen demand added. Hence, the HTP offers several resource recovery opportunities from PM which may also reduce the risks of environmental degradation.

Performance of electro-Fenton process for the treatment of synthetic sulphidic spent caustic waste stream generated from petroleum refineries.

Sulphidic spent caustic (SSC) is an alkaline waste stream which is generated during caustic scrubbing of liquefied petroleum gas and ethylene products. Due to presence of high concentrations of sulphides and phenols, the waste stream requires proper treatment before mixing with the low strength wastewater streams produced from other refinery operations. Electrochemical process is an emerging treatment method that can work efficiently at ambient conditions. The present study reports performance of electro-Fenton (EF) process for the treatment of synthetic SSC wastewater (sulphides = 10 g L-1, phenol = 2 g L-1 and pH = 12.9). The EF runs were carried out for 2 h duration in a reactor equipped with iron electrodes. The effects of H2O2 dose (0.26-1.3 M), current density (1-20 mA cm-2), pH (4.5-12.9) and stirring speed (100-1000 rpm) were investigated on removal of pollutants. The H2O2 was rapidly consumed in initial 30 min during which the significant fraction of the pollutants was degraded or removed. The optimum conditions for EF process were found to be as follows: pH = 4.5, H2O2 dose = 1.05 M, current density = 5 mA cm-2 and stirring speed = 500 rpm. At these conditions, the maximum sulphide and phenol removals from the wastewater were 98% and 91%, respectively. The results will be helpful to the wastewater treatment plant operators worldwide dealing with high concentrations of such pollutants.

Thermal hydrolysis of sewage sludge: Improvement in biogas generation and prediction of global warming potential.

Anaerobic digestion (AD) is a prominent treatment method for the sludge produced from sewage treatment plants. Poor solid reduction and longer retention time are the main drawbacks of AD. Thermal hydrolysis (TH) is a potential pretreatment method for solubilization of sewage sludge (SS) solids thereby improving biogas production during AD post-treatment. In this study, the SS sample (total solids = 1.75 wt% and total chemical oxygen demand (COD) = 15,450 mg L-1) was subjected to TH pretreatment (temperature = 140-180°C and reaction time = 60 minutes) in a 0.7-L capacity stainless-steel high-pressure reactor. At a reaction temperature of 180°C, the maximum solid solubilization (total dissolved solids = 4652 mg L-1) and improved dewaterability (time to filter = 4.7 s.L g-1) were observed. The biochemical methane potential test results showed almost doubling of methane generation from 145 to 284 mL gCOD-1 after TH pretreatment at 180°C. The life cycle assessment approach was used to compare various SS treatment and disposal scenarios, two of which included hydrothermal pretreatment. The scenarios involving hydrothermal pretreatments showed the least global warming potential.

Effect of diaper waste on composting of household wet biodegradable waste in a decentralized system.

Due to changes in lifestyle and improved economic status, the use of diapers is also increasing in developing nations. Hence, there is a need to develop an eco-friendly system for the disposal of discarded diapers which is termed diaper waste (DW). In the present study, the co-composting of DW with household wet biodegradable waste (HWBW) was performed in a compartmentalized rotary drum (CRD) (total capacity = 160 L, number of compartments = 4) under passive aeration conditions. For the co-composting runs, 1 kg of HWBW and DW mixture (mass ratio = 100:0, 90:10, 85:15, and 80:20) was added in four individual compartments daily for 10 days. During the process, the highest temperature of ~ 50-56 °C could be achieved in different compartments for a duration of 2-8 days. The compost yield (i.e., below 4 mm size material) was ranged 10.4-13% after 55 days of composting and the mass of DW was reduced by ~ 61-68%. A mixture of 15% DW and 85% HWBW can be suggested as the best combination for the co-composting process. Based on the "Dewar test" results, the samples recovered after composting could be categorized as "stable". The pot results showed an improvement in the growth of Vigna Radiata when 10% compost sample was mixed with soil whereas with 20% compost in the soil-compost mixture, the plant growth was adversely affected. Hence, co-composting of DW with HWBW can be a feasible proposition which can produce a good quality compost.

Double scleral tunnel technique to prevent glaucoma drainage device exposure.

PURPOSE: To describe a new surgical technique designed to reduce the risk of tube exposure following glaucoma drainage device (GDD) surgery. METHODS: A retrospective, single-center study included all patients who underwent GDD surgery by a single surgeon between January 2018 and December 2019, using a double scleral tunnel technique to secure the tube to the sclera. A 23-gauge needle was used to create a 3 mm partial thickness scleral tunnel near to the GDD plate, with a second partial thickness scleral tunnel created 2.5 mm from the surgical limbus into the anterior chamber (AC). The silicone tube was passed through both scleral tunnels and into the AC. RESULTS: 46 GDD surgeries were performed during the time frame. The mean age of patients was 65 ± 13 years. Mean follow up duration was 27.7 ± 8.15 months (range 11 to 44). Significant reductions in intraocular pressure and number of glaucoma medications were achieved. Zero exposures were recorded occurring during follow-up. CONCLUSION: This double scleral tunnel technique to secure the GDD silicone tubing firmly to the sclera may reduce micro-movements which have been purported to be associated with tissue erosion post GDD surgery. The addition of this simple technique to existing GDD surgery may reduce the risk of post-operative tube exposure.

Secondary pigmentary glaucoma following cosmetic laser treatment to alter iris colour.

Cosmetic alteration of iris colour with implants, along with its secondary complications, is already well described in the literature. However the use of cosmetic iris laser is relatively novel. We report on a rare case of bilateral secondary pigmentary glaucoma, in a young patient who underwent such a treatment to cause a change in iris pigmentation. Data on the safety of such procedures are lacking. Ophthalmic healthcare professionals should be aware of the potentially devastating consequences and encourage caution in patients seeking this novel treatment.

Performance of treatment schemes comprising chromium-hydrogen peroxide-based advanced oxidation process for textile wastewater.

The present study investigated the performance of a chromium-based advanced oxidation process using chromium (as Cr3+ or Cr6+) and H2O2 for the treatment of synthetic and simulated textile wastewaters. With the Cr3+/H2O2 system, the maximum total organic carbon (TOC) and color removals from the synthetic dye wastewater (Remazol Brilliant Violet 5R dye concentration = 100 mg/L) were 75% and 99%, respectively, within 30 min duration ([Cr3+]:[H2O2] = 1:30, stoichiometric H2O2 dose = 2.01 ml/L and pH = 7). Whereas the same catalyst and oxidant combination resulted in chemical oxygen demand (COD) and color removals of ~ 46%, and 84%, respectively, after 3 h of reaction at the optimized reaction conditions (i.e., [Cr3+]:[H2O2] = 1:50, stoichiometric H2O2 dose = 11.6 ml/L and pH = 7) from the simulated textile wastewater (initial pH = 10.2, and COD = 1820 mg/L). Further, the addition of stoichiometric H2O2 dose to the pretreated wastewater and pH adjustment increased the overall COD removal to 77%. Both oxidation and precipitation reactions were found responsible for organics removal from the wastewater. The other alternative involving activated carbon adsorption as second step, was not found as effective as the above scheme. The data on COD removal from simulated textile wastewater could be fit adequately in the retarded first-order kinetic model. Based on the COD and color removal results and preliminary cost analysis, this can be suggested that the Cr3+/H2O2 oxidation process followed by pH adjustment and further H2O2 treatment was the best option for the removal of COD and color from the simulated combined textile wastewater.

Conjunctival erosion following a PRESERFLO® MicroShunt procedure.

PURPOSE: We describe a case of conjunctival erosion following a PRESERFLO® MicroShunt procedure, and the subsequent revision surgery. OBSERVATIONS: Conjunctival erosion was noted overlying the MicroShunt implant at postoperative week 11, 8 weeks following a bleb needling procedure for bleb encapsulation. A brisk leak was observed at the site of erosion. The patient underwent a subsequent revision procedure with repositioning of the MicroShunt implant and mitomycin C (MMC) application. CONCLUSION AND IMPORTANCE: Conjunctival erosion may be a relatively rare but important complication following MicroShunt surgery and may arise from a variety of risk factors. Extra care should be taken during bleb needling in the context of MicroShunt, and needling should be directed posteriorly, beyond the distal tip of the MicroShunt.

Giant pulmonary hamartoma with placental transmogrification-a case report.

Pulmonary hamartomas are rare tumors and are mostly found incidentally in patients investigated for other pathologies. They are frequently small in size, though with some being reported as large as 25 centimeters (cm). We are reporting a case of a huge pulmonary hamartoma (measuring 25.5 × 17.5 × 15.5 cm and weighing about 2200 grams (g)) in a 33-year-old lady with a short duration history of breathlessness. The tumor had origin from the medial border of the left lung, extending into almost the entire left hemithorax and partly into the anterior mediastinum, with no local invasion. The left lower lobe had compression atelectasis due to mass. The mass was successfully resected. The histopathology report showed predominant adipose tissue and cartilaginous differentiation. There were also a few foci of papillary projections with predominant vascular areas, resembling immature placental villi, suggestive of placental transmogrification of the mass.

Hydrothermal carbonization of household wet waste - characterization of hydrochar and process wastewater stream.

In the present study, household wet waste (HWW) pretreatment was explored using hydrothermal carbonization (HTC) to enhance resource recovery opportunities. The pretreatment was performed at 200 °C for 1-8 h duration in a 2 L high pressure reactor. After HTC, the recovered solid hydrochar (HC) showed high calorific value of âˆ¼ 27 MJ/kg compared to 18 MJ/kg of HWW. Moreover, it contained significant amount of oxygen containing acidic functional groups, hence the waste derived HC may also be utilized as adsorbent in wastewater treatment and soil conditioner. The process wastewater (PW) contained several value-added organics including proteins and furfurals. The HTC reaction kinetics showed the conversion of HWW to primary HC as the fastest step (rate constant = 0.0126 min-1). Moreover, the biochemical methane potential test on PW revealed generation of significant amounts of biogas with 55-75% methane. The total energy production from HC and PW was estimated as âˆ¼ 3.3 MJ/kg of HWW.

Optimization for the conditions to prepare sewage sludge derived adsorbent and ciprofloxacin adsorption.

In the present study, sewage sludge (SS) was used to synthesize activated carbon (AC) which was further utilized as adsorbent for the removal of ciprofloxacin (CPX) from synthetic wastewater. The adsorbent was prepared by chemical activation method using ZnCl2 as activating agent. Design of experiments (DOE) approach was explored to determine the optimum operating conditions for the synthesis of AC and CPX removal from the wastewater. The optimum conditions for AC synthesis (i.e., carbonization temperature = ~500°C, activation time = 30 min, and impregnation ratio = 2.26) were decided based on results for three response parameters, that is, adsorbent yield, methylene blue removal, and iodine number. The synthesized adsorbent showed ~93% CPX removal (initial CPX concentration = 100 mg/L) at the following optimum conditions: adsorbent dose = 1.31 g/L, pH = 7 and reaction time = 12 h. Langmuir isotherm model was best fit to the equilibrium adsorption data (maximum adsorption capacity of SS derived AC = 102 mg/g) whereas pseudo-second order model showed the best fit to adsorption kinetic data (adsorption capacity = 77.5 mg/g). An effort was also made to reduce fresh water requirement for adsorbent synthesis by recycling the wastewater produced during chemical activation of SS. PRACTITIONER POINTS: Experiment design approach was used for optimization of adsorbent preparation conditions and CPX removal conditions by waste derived adsorbent. Sewage sludge derived adsorbent had BET surface area of 564 m2 /g which is comparable to commercial activated carbon. 93% CPX adsorption with the sewage sludge derived adsorbent at optimum conditions. Langmuir model better suited the CPX adsorption data. Wastewater recycling and ZnO recovery from wastewater produced during adsorbent synthesis were performed.

Investigation on hydrochar and macromolecules recovery opportunities from food waste after hydrothermal carbonization.

In this paper, the performance of hydrothermal carbonization (HTC) was investigated on real food waste (FW) to improve resource recovery opportunities. The HTC was performed in a high pressure batch reactor (without addition of water) at desired temperatures for different durations to study the properties of solid hydrochar (HC) and process water (PW) produced during the process. The reaction temperature and run time of 200 °C and 1 h, respectively were found suitable to produce the HC (high heating value = ~30 MJ/kg) having properties similar to that of the peat/lignite coal. Moreover, durable pellets could also be prepared from HC without addition of binder. The kinetic constants for HC combustion were also predicted using non-isothermal model-free approach for the data obtained from thermo-gravimetric analysis. In the PW samples recovered after HTC, several value-added compounds like 2,5-hydroxymethyl furfural, humic-like substances (HLS), proteins, carbohydrates and volatile fatty acids could be detected in appreciable quantities. However, longer reaction resulted in further degradation of above macromolecules into VFAs. Based on the observations, a pathway for FW degradation during HTC process is proposed. Moreover, the HLS and proteins mixture recovered from the PW sample exhibited no adverse impact on seed growth. The present study demonstrates that the HTC can be a potential treatment method for FW to recover a variety of useful materials. Further studies should focus on developing cost-effective methods for the recovery of various macromolecules from PW.

Hydrothermal carbonization of centrifuged sewage sludge: Determination of resource recovery from liquid fraction and thermal behaviour of hydrochar.

Safe disposal of the sludge generated from sewage treatment plant is a major challenge worldwide. Hydrothermal carbonization (HTC) is considered a potential pretreatment alternative for sewage sludge to facilitate the improved resource recovery. In the present study, the mixed centrifuged sewage sludge (CSS) was subjected to the HTC pretreatment to determine characteristics of the solid hydrochar (HC) and liquid fraction (LF) with a purpose of energy recovery and extraction of value-added compounds, respectively. HTC was performed in a high pressure batch reactor at 200 °C temperature for 1-8 h duration. The HC produced after HTC resembled with the low quality peat coal whereas the LF contained value-added chemicals such as humic acid (HA) and phosphate phosphorous (PO43-P). Using ammonium sulphate as 'salting out' agent, ~70% of the total HA (~15-16 g/L) could be recovered from the LF. Using the recovered HA, an improvement in the root and shoot lengths of the seeds could be observed. In the subsequent step, the total PO43--P recovery of ~80% was obtained as struvite from the residual wastewater.

Clinical outcomes and hemodynamic performance of Dafodil™ aortic and mitral pericardial bioprosthesis: 1-year results from Dafodil-1 first-in-human trial.

BACKGROUND: Bioprosthesis has been increasingly implanted for the treatment of transvalvular disease across the world. A new Dafodil™ pericardial bioprosthesis (Meril Life Sciences Pvt. Ltd., India) recently approved by Conformité Européenne (CE) is a tri-leaflet, stented, bovine valve. The purpose of Dafodil-1 first-in-human trial was to evaluate clinical safety and performance (including hemodynamic parameters) of the Dafodil pericardial bioprosthesis in patients who underwent aortic or mitral valve replacement. METHODS: This prospective, multicenter clinical trial enrolled 60 patients (Aortic: 30 patients; Mitral: 30 patients) from seven sites across India. Safety endpoints were early (≤30 days) and late (> 30 days) mortality and valve-related morbidity. The performance endpoints were hemodynamic performance, improvement in NYHA functional class, and change in the quality of life using SF-12v1 health survey. RESULTS: From July 2017 to July 2018, 60 patients underwent implantation of the Dafodil pericardial bioprosthesis. Post-operatively, NYHA functional class significantly improved in all the patients (Aortic: 90% NYHA class-I and 10% NYHA class-II; Mitral: 96.55% NYHA class-I and 3.45% NYHA class-II; P < 0.001). There was no death in aortic valve replacement patients till 12-month. In mitral valve replacement patients, early mortalities occurred in three patients, and late mortality occurred in one patient; none of these were valve-related. Freedom from all-cause mortality reported was 93.33% at 12-month. Mean aortic pressure gradient decreased from 52.71 ± 24.47 mmHg [with 0.89 ± 0.70 cm2 effective orifice area (EOA)] pre-operatively to 14.49 ± 6.58 mmHg (EOA: 1.85 ± 0.27 cm2) at 12-month. Overall, the mitral mean pressure gradient and EOA were 4.41 ± 1.69 mmHg and 2.67 ± 0.48 cm2, respectively, at 12-month. Significant improvement (P < 0.05) in the patients' quality of life was reported at all follow-ups. CONCLUSIONS: The clinical safety and performance of the Dafodil pericardial bioprosthesis were favourable at 12-month. Moreover, a study with a larger patient population and longer follow-up is warranted to further assess the device. TRIAL REGISTRATION: Dafodil-1 trial has been prospectively registered on 10/07/2017 under Clinical Trial Registry-India (http://www.ctri.nic.in). (Registration number: CTRI/2017/07/009008).

Segmented Macular Layer Volumes from Spectral Domain Optical Coherence Tomography in 184 Adult Twins: Associations With Age and Heritability.

Purpose: To investigate segmented macular layer volumes from a healthy adult twin cohort (TwinsUK), exploring changes with age and heritability. Methods: Macular spectral domain optical coherence tomography images were acquired from monozygotic (MZ) and dizygotic (DZ) twins in a cross-sectional study. The following layer volumes were derived for circles of 3 and 6 mm diameter around the foveal center, using automated segmentation software: retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer (GCIPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptors (PR), retinal pigment epithelium (RPE), and total retinal volume (TRV). Correlation coefficients (intereye; age; intrapair for MZ and DZ pairs) were quantified; heritability was estimated using structural equation modeling. Results: Scans from 184 participants were included. Intereye correlation was highest for TRV and GCIPL. Negative correlations with age (for 3- or 6-mm areas, or both) were observed for TRV, RNFL, GCIPL, and INL. Positive correlations were observed for PR, RPE, and OPL. For all layers, intrapair correlation was greater for MZ than DZ pairs. Heritability estimates were highest (>80%) for TRV and GCIPL volume, and lowest for RPE volume. Conclusions: Although TRV was negatively correlated with age, all layers did not show negative correlation. Some inner layers thinned with age, whereas some outer volumes increased (not the ONL). Reduced RPE phagocytic function with age and remodeling in the OPL could be contributing factors. Heritability estimates were highest for inner retinal layers (particularly GCIPL), and lowest for RPE volume.

Visual Field Outcomes from the Multicenter, Randomized Controlled Laser in Glaucoma and Ocular Hypertension Trial (LiGHT).

PURPOSE: To compare visual field outcomes of ocular hypertensive and glaucoma patients treated first with medical therapy with those treated first with selective laser trabeculoplasty (SLT). DESIGN: Secondary analysis of patients from the Laser in Glaucoma and Ocular Hypertension study, a multicenter randomized controlled trial. PARTICIPANTS: Three hundred forty-four patients (588 eyes) treated first with medical therapy and 344 patients (590 eyes) treated first with SLT. METHODS: Visual fields (VFs) were measured using standard automated perimetry and arranged in series (median length and duration, 9 VFs over 48 months). Hierarchical linear models were used to estimate pointwise VF progression rates, which were then averaged to produce a global progression estimate for each eye. Proportions of points and patients in each treatment group with fast (<-1 dB/year) or moderate (<-0.5 dB/year) progression were compared using log-binomial regression. MAIN OUTCOME MEASURES: Pointwise and global progression rates of total deviation (TD) and pattern deviation (PD). RESULTS: A greater proportion of eyes underwent moderate or fast TD progression in the medical therapy group compared with the SLT group (26.2% vs. 16.9%; risk ratio [RR], 1.55; 95% confidence interval [CI], 1.23-1.93; P < 0.001). A similar pattern was observed for pointwise rates (medical therapy, 26.1% vs. SLT, 19.0%; RR, 1.37; 95% CI, 1.33-1.42; P < 0.001). A greater proportion of pointwise PD rates were categorized as moderate or fast in the medical therapy group (medical therapy, 11.5% vs. SLT, 8.3%; RR, 1.39; 95% CI, 1.32-1.46; P < 0.001). No statistical difference was found in the proportion of eyes that underwent moderate or fast PD progression (medical therapy, 9.9% vs. SLT, 7.1%; RR, 1.39; 95% CI, 0.95, 2.03; P = 0.0928). CONCLUSIONS: A slightly larger proportion of ocular hypertensive and glaucoma patients treated first with medical therapy underwent rapid VF progression compared with those treated first with SLT.

Eco-friendly decolorization and degradation of reactive yellow 145 textile dye by Pseudomonas aeruginosa and Thiosphaera pantotropha.

Dyes are toxic and inherently resistant to microbial degradation. In this study, decolorization and degradation of textile dye reactive yellow 145 (RY145) were evaluated using pure bacterial strains Pseudomonas aeruginosa (RS1) and Thiosphaera pantotropha ATCC 35512. In nutrient broth under static condition, complete decolorization of 50 mg L-1 RY145 could be achieved within 96 h and 72 h, for Pseudomonas aeruginosa (RS1) and Thiosphaera pantotropha, respectively. In contrast, under shaking condition both the cultures could achieve only 50% decolorization in 96 h. Treatment under sequential static and shaking condition resulted in complete decolorization and 65% mineralization after 96 h. Higher dye concentration in excess of 100 mg L-1 and 50 mg L-1 decreased the extent of dye mineralization in Pseudomonas aeruginosa and Thiosphaera pantotropha, respectively. Even with the repetitive addition of the dye, both the strains were capable of decolorizing the dye. Acclimatized cultures showed 54% decolorization of RY145 in mineral media (MM) even in the absence of a readily degradable external carbon source. Amongst various individual carbon and nitrogen sources, maximum decolorization was observed in MM supplemented with peptone as carbon and nitrogen source at pH 7 under static condition.

Efficacy of Repeat Selective Laser Trabeculoplasty in Medication-Naive Open-Angle Glaucoma and Ocular Hypertension during the LiGHT Trial.

PURPOSE: To determine the efficacy of repeat selective laser trabeculoplasty (SLT) in medication-naive open-angle glaucoma (OAG) and ocular hypertensive (OHT) patients requiring repeat treatment for early to medium-term failure during the Laser in Glaucoma and Ocular Hypertension (LiGHT) trial. DESIGN: Post hoc analysis of SLT treatment arm of a multicenter prospective randomized controlled trial. PARTICIPANTS: Treatment-naive OAG or OHT requiring repeat 360-degree SLT within 18 months. Retreatment was triggered by predefined IOP and disease-progression criteria (using objective individualized target IOPs). METHODS: After SLT at baseline, patients were followed for a minimum of 18 months after second (repeat) SLT. A mixed-model analysis was performed with the eye as the unit of analysis, with crossed random effects to adjust for correlation between fellow eyes and repeated measures within eyes. Kaplan-Meier curves plot the duration of effect. MAIN OUTCOME MEASURES: Initial (early) IOP lowering at 2 months and duration of effect after initial and repeat SLT. RESULTS: A total of 115 eyes of 90 patients received repeat SLT during the first 18 months of the trial. Pretreatment IOP before initial SLT was significantly higher than before retreatment IOP of repeat SLT (mean difference, 3.4 mmHg; 95% confidence interval [CI], 2.6-4.3 mmHg; P < 0.001). Absolute IOP reduction at 2 months was greater after initial SLT compared with repeat SLT (mean difference, 1.0 mmHg; 95% CI, 0.2-1.8 mmHg; P = 0.02). Adjusted absolute IOP reduction at 2 months (adjusting for IOP before initial or repeat laser) was greater after repeat SLT (adjusted mean difference, -1.1 mmHg, 95% CI, -1.7 to -0.5 mmHg; P = 0.001). A total of 34 eyes were early failures (retreatment 2 months after initial SLT) versus 81 later failures (retreatment >2 months after initial SLT). No significant difference in early absolute IOP reduction at 2 months after repeat SLT was noted between early and later failures (mean difference, 0.3 mmHg; 95% CI, -1.1 to 1.8 mmHg; P = 0.655). Repeat SLT maintained drop-free IOP control in 67% of 115 eyes at 18 months, with no clinically relevant adverse events. CONCLUSIONS: These exploratory analyses demonstrate that repeat SLT can maintain IOP at or below target IOP in medication-naive OAG and OHT eyes requiring retreatment with at least an equivalent duration of effect to initial laser.