The effect of the extent of the incision in the Schlemm canal on the surgical outcomes of suture trabeculotomy for open-angle glaucoma

Historical and Contemporary Debates in Schlemm's Canal-Based MIGS

Glaucoma is one of the primary causes of blindness worldwide. Canal opening surgery, a type of minimally invasive glaucoma surgery (MIGS) applied in cases of mild to moderate glaucoma, has gained increasing popularity in recent years due to its efficacy in reducing the intraocular pressure, its safety profile, the simplicity of its technique, and the reduced likelihood of compromised vision. Nevertheless, the existing body of histopathological studies remains insufficient for a comprehensive understanding of post-surgical wound healing. Consequently, debates persist among researchers regarding the mechanism through which Schlemm's canal opening surgery reduces the intraocular pressure, as well as the surgical techniques that may impact the outcomes and the factors influencing surgical success. As the history of MIGS is relatively short and lacks sufficient systemic reviews or meta-analyses evaluating the influence of individual factors, this review was conducted to illuminate the disparities in researchers' opinions at the current stage of research.

Trabeculotomy Using the Kahook Dual Blade for Exfoliation Glaucoma and Primary Open Angle Glaucoma: Comparison of Outcomes According to Incision Range

PRCIS

Large amount of trabeculotomy with Kahook Dual Blade (KDB) confers better intraocular pressure (IOP) lowering.

PURPOSE

We compared the postoperative outcomes of trabeculotomy using the KDB in patients with exfoliation glaucoma (EXG) and primary open angle glaucoma between the 120-degree incision and the 210- to 240-degree incision groups.

PATIENTS AND METHODS

We retrospectively analyzed the postoperative outcomes of trabeculotomy performed using the KDB in 101 eyes with EXG and primary open angle glaucoma, who received 120- and 210- to 240-degree incisions at Kumamoto University Hospital between April 25, 2018, and August 11, 2021. Kaplan-Meyer survival curves were used to assess the outcomes. Surgical failure was defined as IOP ≥21 mm Hg (criterion A) and ≥19 mm Hg (criterion B), or an IOP ≤4 mm Hg in either criterion and the need for additional glaucoma surgery.

RESULTS

In total, 64 and 37 eyes were included in the 120 and 210- to 240-degree groups, respectively. The 210- to 240-degree group had a higher 1-year success rate compared with the 120-degree group, both when considering all eyes and when considering only those with EXG (P<0.05).

CONCLUSIONS

In trabeculotomy with KDB, a 210- to 240-degree incision was more effective than a 120-degree incision in lowering IOP in EXG cases.

Which is More Effective and Safer? Comparison of Propensity Score-Matched Microhook Ab Interno Trabeculotomy and iStent Inject

INTRODUCTION

The purpose of this study was to compare the surgical outcomes between ab interno trabeculotomy (LOT) and iStent inject W implantation (iStent) both combined with cataract surgery, matching the background factors including age, intraocular pressure (IOP), medication score, central corneal thickness (CCT), and axial length.

METHODS

A total of 100 eyes from 75/79 patients with primary open-angle glaucoma were included in the LOT/iStent groups. The background factors were matched between the two groups using the propensity score.

RESULTS

There were no significant differences in age, IOP, medication score, CCT, and axial length, preoperatively. The postoperative medication scores were 1.3 ± 1.2 and 1.2 ± 1.2 in the LOT and iStent groups. The postoperative IOPs were 12.8 ± 2.8 and 13.1 ± 2.4 mmHg in the LOT and iStent groups, respectively. The changes in the medication score were  - 0.64 ± 1.4 and  - 0.44 ± 1.6 in the LOT and iStent groups, respectively. The changes in the IOP were  - 2.1 ± 3.3 and  - 1.5 ± 3.0 mmHg in the LOT and iStent groups, respectively. These values were not significantly different between the two groups. The postoperative IOP and changes in the IOP were significantly associated with preoperative IOP and CCT. There was no significant difference in the occurrence of postoperative complications (hyphema, 11.0% and 6.0%, and transient ocular hypertension, 8.0% and 5.0%, in the LOT and iStent groups, respectively).

CONCLUSION

LOT and iStent have similar surgical outcomes with sufficient safety. Postoperative IOP was significantly associated with preoperative IOP and CCT in both groups.

Conventional Trabeculotomy versus Gonioscopy-Assisted Transluminal Trabeculotomy: A Retrospective Cohort Study

Background: Conventional trabeculotomy (CT) is performed in an ab-externo manner with at most 120 degrees of incision area of Schlemm’s canal (SC). Recently, gonioscopy-assisted transluminal trabeculotomy (GATT), which makes possible a 360-degree incision area of SC in an ab-interno manner, is introduced. The purpose of this study was to compare surgical outcomes for CT and GATT with and without simultaneous phacoemulsification over 24 months and to identify factors associated with surgical success. Results: Patients’ baseline characteristics were not significantly different between two groups. The surgical success rate in CT and GATT with phacoemulsification groups were 40.4% and 96.6% and were significantly higher in the GATT group than in the CT group (p < 0.001). However, the surgical success rate in CT and GATT without phacoemulsification groups were 40.8% and 54.2%, and there were no significant differences between two groups without phacoemulsification (p = 0.55). Similarly, the postoperative IOP was significantly lower in the GATT group than in the CT group only in eyes with simultaneous phacoemulsification. There were no significant differences in the numbers of glaucoma medications between the two groups. Additional glaucoma surgery was needed in 13.2% and 25.9% of patients in the GATT and CT groups, respectively (p = 0.157). The multivariate logistic regression analysis revealed that the surgical success of trabeculotomy was significantly associated with combined phacoemulsification and the type of glaucoma surgery (GATT). Conclusion: Although both groups without phacoemulsification had a similar surgical success and IOP-lowering effect, GATT combined with phacoemulsification had a higher surgical success rate and a greater IOP-lowering effect compared with combined CT and phacoemulsification. Multivariate logistic regression analysis showed that the factors associated with higher surgical success at one year and two years postoperatively were the combined phacoemulsification procedure and the GATT.

Comparison of Postoperative Hyphemas between Microhook Ab Interno Trabeculotomy and iStent Using a New Hyphema Scoring System

We have been using our in-house scoring system of hyphemas, i.e., Shimane University RLC postoperative hyphema scoring system (SU-RLC), which we designed to classify postoperative hyphema. SU-RLC classifies the severities of hyphemas based on three factors, i.e., red blood cells (RBCs) (R) 0-3, layer formation (L) 0-3, and clot (C) 0-1, by slit-lamp observation. To test the clinical usefulness of the SU-RLC for quantifying the postoperative hyphema severity, the SU-RLC scores were compared between eyes that underwent different minimally invasive glaucoma surgery (MIGS) procedures, i.e., Tanito microhook ab interno trabeculotomy and cataract extraction (TMH-CE) (n = 64 eyes of 64 subjects; mean age ± standard deviation, 72.4 ± 8.1 years) and iStent-CE (n = 21 eyes of 21 subjects; 76.1 ± 10.6 years). Compared to the iStent-CE, higher hyphema scores with the TMH-CE were found for the R scores on postoperative days 1, 2, and 3; for the L score on postoperative day 1; and for the C score on postoperative day 2. The sums of the R, L, and C scores (RLC) on postoperative day 1 were 3.2 ± 1.1 with the TMH-CE and 1.1 ± 1.3 with the iStent-CE; the scores reached almost 0 by 2 weeks in both groups. Significant differences in the RLC scores between the surgical groups were found on postoperative days 1, 2, and 3. Multivariate analyses showed that the TMH-CE rather than iStent-CE was associated with higher R, C, and RLC scores; anticoagulant/antiplatelet use was associated with higher R score; and myopia was associated with a higher C score. In the TMH-CE group, myopia was associated with a higher C score. In the iStent-CE group, anticoagulant/antiplatelet use was associated with higher R and RLC scores; and higher postoperative 1-day intraocular pressure was associated with a higher C score. The SU-RLC successfully detected the difference in hyphema severity between different MIGS procedures; thus, we concluded that our classification system may be feasible to evaluate hyphemas after glaucoma surgery.

Gonioscopy-assisted transluminal trabeculotomy versus goniotomy with Kahook dual blade in patients with uncontrolled juvenile open-angle glaucoma: a retrospective study

Background

To compare the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) and Kahook Dual Blade (KDB) excisional goniotomy in patients with uncontrolled juvenile open-angle glaucoma (JOAG).

Methods

Thirty-three patients (46 eyes) were included in this single-center, retrospective, comparative study and treated with GATT (36 eyes) or KDB goniotomy (13 eyes). Intraocular pressure (IOP), number of glaucoma medications, adverse events, and additional anti-glaucoma procedures were collected during pre- and postoperative visits. Surgical success was defined as 6 mmHg ≤ IOP ≤ 18 mmHg and ≥ 20% IOP reduction from baseline with (partial success) or without (complete success) IOP-lowering medications.

Results

The mean ± SD preoperative IOP was 30.48 ± 12.9 mmHg and 26.08 ± 13.1 mmHg (P = 0.164) on 3.71 ± 0.46 and 3.08 ± 0.86 (P = 0.023) glaucoma medications in GATT and KDB group, respectively. At 3 months, the mean ± SD IOP was 15.48 ± 5.93 mmHg and 20.0 ± 10.8 mmHg after GATT and KDB, respectively (P = 0.072). The percentage of IOP lowering from baseline was 44.4 in the GATT group and 14.1 in the KDB group (P = 0.011). The mean reduction in medications was 2.6 ± 1.7 and 0.8 ± 1.2 three months after GATT and KDB, respectively (P < 0.001). Cumulative proportion of partial and complete success were 65.6 and 44.7% in the GATT group, 30.8 and 15.4% in the KDB group at 6 months. Additional procedures were required in 13.9% of cases after GATT and in 61.5% after KDB (P = 0.001). Patients in the GATT group with prior anti-glaucoma procedures and postoperative IOP spikes were more likely to fail, while those with complete trabeculotomy had a better prognosis.

Conclusions

Reduction of IOP and medications were greater after GATT in uncontrolled JOAG eyes. Whereas, more additional IOP-lowering procedures were required after KDB goniotomy.

Trial registration

This study was registered under the Chinese Clinical Trial Registry (ChiCTR2000034172, 27/06/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02159-z.

Minimally Invasive Glaucoma Surgery-to Remove or Preserve the Trabecular Meshwork: That is the Question?

How to cite this article: Dada T, Mahalingam K, Bhartiya S. Minimally Invasive Glaucoma Surgery—to Remove or Preserve the Trabecular Meshwork: That is the Question? J Curr Glaucoma Pract 2021;15(2):47–51.

Corneal Higher-Order Aberrations after Microhook ab Interno Trabeculotomy and Goniotomy with the Kahook Dual Blade: Preliminary Early 3-Month Results

We examined postoperative corneal higher-order aberrations (HOAs) present after combined phacoemulsification with either microhook ab interno trabeculotomy (μLOT-Phaco) or goniotomy, using the Kahook Dual Blade (KDB-Phaco). Retrospective study: A total of 45 eyes underwent μLOT-Phaco and KDB-Phaco (LOT-Phaco) procedures, with 21 eyes that underwent cataract surgery alone used as controls. Visual acuity and corneal HOAs, coma-like aberrations, and spherical-like aberrations were analyzed before and at 1, 2, and 3 months after the surgeries. Risk factors that could potentially influence HOAs were evaluated. No significant postoperative changes were noted for corneal HOAs, coma-like aberrations, and spherical-like aberrations after cataract surgery alone. The mean corneal HOAs, coma-like aberrations, and spherical-like aberrations were 0.222 ± 0.115 μm, 0.203 ± 0.113 μm, and 0.084 ± 0.043 μm at baseline and 0.326 ± 0.195 μm (p < 0.001), 0.302 ± 0.289 μm (p = 0.03), and 0.150 ± 0.115 μm (p < 0.001) at 3 months after LOT-Phaco, respectively. Results of the analysis for risk factors suggested that a longer incision in Schlemm’s canal could influence corneal HOAs, coma-like aberrations, and spherical-like aberrations after LOT-Phaco. Although no significant postoperative changes were observed in corneal HOAs and coma-like or spherical-like aberrations after cataract surgery alone, a significant increase in corneal HOAs and coma-like or spherical-like aberrations remained after the LOT-Phaco procedure.

Prediction of trabecular meshwork-targeted micro-invasive glaucoma surgery outcomes using anterior segment OCT angiography

We performed a prospective, longitudinal study to investigate the association between the preoperative intrascleral vasculature assessed using anterior segment (AS)-optical coherence tomography angiography (OCTA) and surgical outcomes of trabecular meshwork-targeted micro- or minimally invasive glaucoma surgery (MIGS). We included 37 patients with primary open-angle glaucoma. Preoperative AS-OCTA images of the sclero-conjunctiva of the nasal corneal limbus were acquired in the superficial (conjunctival) and deep (intrascleral) layers. The vessel densities (VDs) of each layer were measured separately in the entire area, limbal side, and fornix area. Surgical success was determined by postoperative intraocular pressure (IOP) and IOP reduction. Twenty-three and 14 eyes were classified as having successful and unsuccessful outcomes, respectively. The deep VDs of the entire area and fornix area were significantly lower in the successful group (P = 0.031 and P = 0.009). The success rate was significantly higher for eyes with a lower deep VD than for eyes with a higher deep VD. A greater IOP reduction was significantly associated with lower deep VD in the fornix area (P = 0.022) and higher preoperative IOP (P < 0.001). These results indicate that intrascleral vasculature assessed using preoperative AS-OCTA was negatively correlated with surgical success and IOP reduction resulting from trabecular meshwork-targeted MIGS. AS-OCTA images might help predict MIGS outcomes.

One-year outcomes of microhook trabeculotomy versus suture trabeculotomy ab interno

Purpose

To compare clinical success rates and reductions in intraocular pressure (IOP) and IOP-lowering medication use following suture trabeculotomy ab interno (S group) or microhook trabeculotomy (μ group).

Methods

This retrospective review collected data from S (n = 104, 122 eyes) and μ (n = 42, 47 eyes) groups who underwent treatment between June 1, 2016, and October 31, 2019, and had 12-month follow-up data including IOP, glaucoma medications, complications, and additional IOP-lowering procedures. The Kaplan–Meier survival analysis was used to evaluate treatment success rates defined as normal IOP (> 5 to ≤ 18 mm Hg), ≥ 20% reduction of IOP from baseline at two consecutive visits, and no further glaucoma surgery.

Results

Schlemm’s canal opening was longer in the S group than in the μ group (P < 0.0001). The Kaplan–Meier survival analysis of all eyes showed cumulative clinical success rates in S and µ groups were 71.1% and 61.7% (P = 0.230). The Kaplan–Meier survival analysis of eyes with preoperative IOP ≥ 21 mmHg showed cumulative clinical success rates in S and μ groups were 80.4% and 60.0% (P = 0.0192). There were no significant differences in postoperative IOP at 1, 3, and 6 months (S group, 14.9 ± 5.6, 14.6 ± 4.5, 14.6 ± 3.9 mmHg; μ group, 15.8 ± 5.9, 15.2 ± 4.4, 14.7 ± 3.7 mmHg; P = 0.364, 0.443, 0.823), but postoperative IOP was significantly lower in the S group at 12 months (S group, 14.1 ± 3.1 mmHg; μ group, 15.6 ± 4.1 mmHg; P = 0.0361). There were no significant differences in postoperative numbers of glaucoma medications at 1, 3, 6, and 12 months (S group, 1.8 ± 1.6, 1.8 ± 1.5, 2.0 ± 1.6, 1.8 ± 1.5; μ group, 2.0 ± 1.6, 2.0 ± 1.6, 2.1 ± 1.6, 2.2 ± 1.7; P = 0.699, 0.420, 0.737, 0.198).

Conclusion

S and µ group eyes achieved IOP reduction, but μ group eyes had lower clinical success rates among patients with high preoperative IOP at 12 months.

Comparison of Surgical Outcomes Between Ab Interno Suture Trabeculotomy and Ab Externo Metal Trabeculotomy in Adult Patients with Glaucoma

Purpose

To compare the outcomes of ab interno suture trabeculotomy (AbI-TLO) and ab externo metal trabeculotomy (AbE-TLO) in adult patients with glaucoma aged over 40 years.

Patients and Methods

A retrospective chart review was conducted, including adult patients with glaucoma who underwent AbI-TLO or AbE-TLO between January 2015 and June 2019. A single surgeon (YO) performed all the operations. Eighty-one patients (81 eyes) were included in this study. Surgical success was defined as a postoperative intraocular pressure (IOP) of ≤18 mmHg and an IOP reduction of ≥20% from the preoperative IOP, without requiring additional glaucoma surgery. Success rates were assessed using Kaplan-Meier survival curves and log-rank (Mantel-Cox) tests, while risk factors were analyzed using the Cox proportional hazards model.

Results

Forty-nine patients who underwent AbI-TLO and 32 patients who underwent AbE-TLO were studied; the preoperative IOPs were 27.9 ± 7.3 (mean ± standard deviation) mmHg and 25.6 ± 8.1 mmHg in the AbI-TLO and AbE-TLO groups, respectively (p=0.217). The 12-month postoperative IOPs were 15.8 ± 4.0 mmHg and 16.3 ± 4.2 mmHg in the AbI-TLO and AbE-TLO groups, respectively (p=0.724). The surgical success rates at 12 months were 77.6% and 62.5% in the AbI-TLO and AbE-TLO groups, respectively (p=0.144). Postoperative hyphema with level formation and ocular hypertension over 30 mmHg were observed in 22.4% and 26.5% of patients in the AbI-TLO group and 18.8% and 12.5% of those in the AbE-TLO group, respectively. Stepwise multivariate Cox regression analysis showed that a longer axial length was a risk factor for surgical failure (hazard ratio: 2.030; p=0.042).

Conclusion

AbI-TLO and AbE-TLO had similar surgical outcomes and postoperative complications. A longer axial length was associated with an insufficient IOP reduction.

Comparison of Efficacy between 120° and 180° Schlemm's Canal Incision Microhook Ab Interno Trabeculotomy

We compared surgical outcomes in patients with either primary open-angle glaucoma or exfoliation glaucoma after undergoing combined phacoemulsification with either a 120° or 180° incision during a Schlemm's canal microhook ab interno trabeculotomy (μLOT-Phaco). This retrospective comparative case series examined 52 μLOT-Phaco eyes that underwent surgery between September 2017 and December 2020. Surgical qualified success was defined as an intraocular pressure (IOP) of ≤20 mmHg, ≥20% IOP reduction with IOP-lowering medications, and no additional glaucoma surgery. Success rates were evaluated by Kaplan-Meier survival analysis. The number of postoperative IOP-lowering medications and occurrence of complications were also assessed. Mean preoperative IOP in the 120° group was 16.9 ± 7.6 mmHg, which significantly decreased to 10.9 ± 2.7 mmHg (p < 0.01) and 11.1 ± 3.1 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.8 ± 1.4 to 1.4 ± 1.4 (p < 0.01) at 24 months. Mean preoperative IOP in the 180° group was 17.1 ± 7.0 mmHg, which significantly decreased to 12.1 ± 3.2 mmHg (p = 0.02) and 12.9 ± 1.4 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.9 ± 1.2 to 1.4 ± 1.5 (p < 0.01) at 24 months. The probability of qualified success at 24 months in the 120° and 180° groups was 50.4% and 54.6%, respectively (p = 0.58). There was no difference observed for hyphema formation or IOP spikes. Surgical outcomes were not significantly different between the 120° and 180° incisions in Schlemm's canal.

Midterm Results of Microhook ab Interno Trabeculotomy in Initial 560 Eyes with Glaucoma

All the 560 glaucomatous eyes of 375 Japanese subjects (181 men, 194 women; mean age ± standard deviation, 76.0 ± 13.2 years) who underwent microhook ab interno trabeculotomy (µLOT) alone (159 eyes, 28%) or combined µLOT and cataract surgery (401 eyes, 72%) performed by one surgeon at Matsue Red Cross Hospital between May 2015 and March 2018 to control intraocular pressure (IOP) were retrospectively assessed. Preoperative and postoperative IOPs, numbers of antiglaucoma medications, the logarithm of the minimum angle of resolution visual acuity (logMAR VA), anterior chamber (AC) flare, visual field mean deviation (MD), and corneal endothelial cell density (CECD) were compared up to 36 months. Surgical complications and required interventions were described. The duration of the follow-up was 405 ± 327 (range, 2–1326) days. The mean preoperative IOP (20.2 ± 7.0 mmHg) and number of antiglaucoma medications (2.8 ± 1.1) decreased to 13.9 ± 4.5 mmHg (31% reduction, p < 0.0001) and 2.5 ± 1.0 (11% reduction, p < 0.0001), respectively, at the final visit. After combined surgery, compared with preoperatively, the final VA improved 0.11 logMAR (p < 0.0001), AC flare increased 4.5 photon counts/msec (p = 0.0011), MD improved 0.6 decibel (p < 0.0001), and the CECD decreased 6% (p < 0.0001). Layered hyphema (172 eyes, 31%) and hyphema washout (26 eyes, 5%) were the most common postoperative complication and intervention, respectively. At the final visit, 379 (69%) eyes achieved successful IOP control of ≤18 mmHg and ≥20% IOP reduction, and 349 (64%) eyes achieved successful IOP control of ≤15 mmHg and ≥20% IOP reduction. Older age, steroid-induced glaucoma, developmental glaucoma, and the absence of postoperative complications were associated with lower final IOP; exfoliation glaucoma, other types of glaucoma, and higher preoperative IOP were associated with higher final IOP. µLOT has a significant IOP-lowering potential in patients with glaucoma, and improves visual function when combined with cataract surgery.

Effectiveness and limitations of minimally invasive glaucoma surgery targeting Schlemm's canal

Glaucoma surgery is performed to lower intraocular pressure (IOP); ideally, the IOP reduction is safely maintained for an extended period of time. Although trabeculectomy was considered the gold standard for glaucoma surgery for many years because of its effective IOP reduction, yet now it is considered unsafe because of serious complications. In recent years, minimally invasive glaucoma surgery (MIGS), which emphasizes safety and can be performed rapidly, has become widespread. Because MIGS does not involve conjunctival incisions, patients can undergo future trabeculectomy. If IOP reduction can be maintained safely, the number of anti-glaucoma drops can be reduced and visual function maintained, good outcomes for patients with glaucoma. Currently, many types of MIGS approved in Japan are reported to yield relatively good results, with targets of approximately 15-19 mmHg. However, the IOP-lowering effects of MIGS are limited. In procedures targeting Schlemm's canal, it is difficult to lower IOP beyond episcleral venous pressure. In some instances, a beneficial effect cannot be achieved if function is reduced beyond the collector channel. There are many unclear aspects regarding long-term outcomes following MIGS. Notably, investigation is ongoing to determine which patients are likely to benefit most from surgery. Based on previous reports, this review describes the characteristics and results of MIGS, approved in Japan, as well as underlying factors that affect the preoperative predictions and outcomes of the surgical procedure.

12-month randomised trial of 360° and 180° Schlemm's canal incisions in suture trabeculotomy ab interno for open-angle glaucoma

Background/Aims

To perform a 12-month comparison between the different extents and locations of Schlemm’s canal incisions during suture trabeculotomy ab interno for open-angle glaucoma (OAG).

Methods

This is a prospective, single-centre, three-arm randomised trial. A total of 99 eyes of 99 patients were randomly assigned to one of three groups: the 360° incision group (n=34), the upper-180° incision group (n=34) and the lower-180° incision group (n=31). Intraocular pressure (IOP), number of medications and complications were evaluated until 12 months after surgery. Surgical success (with or without medication) was defined as IOP ≤21 mmHg and ≥20% IOP reduction (criterion A) or IOP ≤15 mmHg and ≥20% IOP reduction (criterion B).

Results

The mean IOP (±SD) in all eyes was reduced from 18.6 (5.9) mmHg with 3.1 (1.1) medications to 13.7 (3.4) mmHg (20.8% reduction; p<0.001) with 1.4 (1.3) medications (p<0.001) at postoperative 12-month. Each group produced comparable mean reductions in both IOP and the number of medications throughout 12 months of follow-up. Kaplan-Meier cumulative survival analyses showed no significance among these three groups for criterion A and criterion B. Postoperative hyphema with niveau formation occurred significantly more in the 360° group than in the lower-180° group (p=0.031).

Conclusions

The different extents and locations of Schlemm’s canal incisions during suture trabeculotomy ab interno for OAG, including the 360° incision, the upper-180° incision and the lower-180° incision, do not affect both the IOP reduction and the medications throughout 12 months of follow-up.

Trial registration number

UMIN000021169.

Gonioscopy-assisted Transluminal Trabeculotomy in Uveitic Glaucoma Secondary to Juvenile Idiopathic Arthritis

Gonioscopy-assisted transluminal trabeculotomy (GATT) is a minimally invasive ab interno procedure, performed with guidance of an illuminating microcatheter device (iTrack). The pathophysiology of raised intraocular pressure (IOP) in uveitic glaucoma is commonly due to increased resistance at the trabecular meshwork-Schlemm canal. By removing this resistance, GATT can potentially control the IOP. In addition, the ab interno approach avoids violating the conjunctiva and reduces the risk of complications including infection, leak, and hypotony. In this series, we discuss 3 uveitic glaucoma cases secondary to juvenile idiopathic arthritis (JIA) that underwent GATT. Case 1 was a 16-year-old phakic female with a preoperative IOP of 25 to 33 mm Hg had 360-degree GATT; her IOP remained stable at 6 to 10 mm Hg over 14 months. Case 2 was a 23-year-old pseudophakic female with a preoperative IOP of 28 to 34 mm Hg had 180-degree GATT; her IOP reduced to 8 mm Hg over 10 months. Case 3 was an 8-year-old aphakic male with a preoperative IOP of 21 to 32 mm Hg had 360-degree GATT; his IOP remained stable at 13 to 15 mm Hg over 21 months. In our limited case series, GATT is very successful in controlling IOP in young uveitic patients with JIA by surgically targeting the underlying pathophysiology.

Rate of Complete Catheterization of Schlemm's Canal and Trabeculotomy Success in Primary and Secondary Childhood Glaucomas

PURPOSE

Despite the increasing use of microcatheters to perform 360-degree trabeculotomy, the rate of complete Schlemm's canalization in different forms of pediatric glaucoma is under-reported.

DESIGN

Retrospective institutional observational case series.

METHODS

Ocular diagnoses and surgical details of 60 pediatric patients (≤18 years old) who underwent trabeculotomy between 2013 and 2019 were collected. Surgical success was defined as an intraocular pressure (IOP) of 5-20 mm Hg and no additional IOP-lowering surgery.

RESULTS

Eighty-five eyes of 60 patients underwent trabeculotomy. For bilateral cases, the first eye to undergo surgery was included for analysis. Diagnoses included primary congenital glaucoma (PCG n = 22), juvenile open angle glaucoma (JOAG n = 16), glaucoma following cataract surgery (GFCS n = 15), and other secondary forms of glaucoma (n = 7). Canalization using a microcatheter was attempted in 52 of 60 eyes (87%) of which 21 (40%) achieved full 360-degree. Complete canalization was attained in 69% of JOAG patients, which was significantly higher than in PCG patients (22%; P = 0.007), but not GFCS (36%) and other secondary glaucoma (29%). The 5-year survival rate for all eyes was 75% with 95% confidence interval (CI), 57 to 86. Survival curves for 360-degree catheter, 270-degree to 360-degree combined catheter/Harms trabeculotome, and <180-degree Harms trabeculotome trabeculotomies were significantly different (P < 0.001) with 5-year survival rates of 100%, 69% with 95% CI, 16 to 93, and 48% with 95% CI, 29 to 64, respectively.

CONCLUSIONS

A 360-degree catheter trabeculotomy is highly effective in obtaining IOP control; however, complete canalization of Schlemm's canal is most frequently achieved in JOAG patients. Congenital anomalies or scarring from previous surgeries, which prevents full canalization, may inherently decrease success of angle surgery in other glaucoma.

Reduction of Intraocular Pressure by Additional Trabeculotomy Ab Externo in Eyes With Primary Open-angle Glaucoma

PURPOSE

The purpose of this study was to determine whether a second trabeculotomy (LOT) can reduce the intraocular pressure (IOP) in eyes with primary open-angle glaucoma (POAG) that had undergone an unsuccessful LOT as the initial surgery.

PATIENTS AND METHODS

LOT ab externo was performed as a second surgery on 37 eyes of 34 POAG patients who had undergone an unsuccessful LOT as the initial surgery. The main outcome measure was the postoperative IOPs, and surgical failures were defined as eyes with a post-LOT IOP>20 mm Hg. The eyes were divided into 3 groups; those that underwent LOT as both the initial and additional surgery (L-L group), those that underwent LOT as the initial surgery and combined LOT and cataract surgery (cLOT-IOL) as the additional surgery (L-cL group), and those that underwent cLOT-IOL as the initial surgery and LOT as the additional surgery (cL-L group).

RESULTS

The IOP was reduced after the additional LOT at postoperative 24 months in the L-L group from 20.0±3.0 mm Hg to 15.3±2.6 mm Hg (P<0.001), the L-cL group from 19.8±1.6 mm Hg to 15.8±3.2 mm Hg (P=0.029), and the cL-L group from 20.1±2.7 mm Hg to 15.5±2.3 mm Hg (P=0.014). There were no differences in the preoperative and postoperative IOPs between the initial-operated and additional-operated eyes. The success rates were improved by the additional surgery in the L-L group (P<0.001) and the L-cL group (P=0.029), but the rate was worsened in the cL-L group (P<0.001).

CONCLUSIONS

These results indicate that LOT is a reasonable choice as an additional glaucoma surgery after failure of an initial LOT.

360-degree suture trabeculotomy ab interno to treat open-angle glaucoma: 2-year outcomes

Purpose

The purpose of this study was to evaluate the efficacy of 360-degree suture trabeculotomy (360S-LOT) ab interno for treating open-angle glaucoma (OAG). Risk factors of surgical failure were examined.

Patients and methods

360S-LOT ab interno alone was performed for patients with uncontrolled OAG, and combined 360S-LOT ab interno/phacoemulsification was performed for patients with controlled OAG with a visually significant cataract between March 2014 and September 2015 at a single center. The patients were prospectively followed for 2 years. The main outcome measures included 2-year intraocular pressure (IOP), number of anti-glaucoma medications used, postoperative complications, and predictive factors of surgical failure. Kaplan-Meier analysis was performed, with surgical success (with or without medication use) defined as postoperative IOP ≤15 mmHg and IOP reduction ≥20% (criterion A) or IOP ≤12 mmHg and IOP reduction ≥30% (criterion B). Predictive factors were evaluated using Cox proportional hazard ratios.

Results

A total of 64 eyes of 64 patients were included, and 50 (78%) eyes of 64 eyes underwent a phacoemulsification combination procedure. Surgery significantly reduced IOP from 18.4 ± 2.9 mmHg before surgery to 13.4 ± 3.0 mmHg after surgery (P < 0.001). Patients used an average of 1.8 ± 1.5 medications before surgery and 1.3 ± 1.5 medications after surgery (P = 0.101). No serious postoperative complications were observed. The probability of surgical success was 49.2% and 16.0% using criteria A and B, respectively. No risk factors of surgical failure were identified.

Conclusion

The 360S-LOT ab interno procedure is a favorable option for treating eyes with mild or moderate OAG.