Characterization of Peripheral Anterior Synechiae Formation After Microhook Ab-interno Trabeculotomy Using a 360-Degree Gonio-Camera

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.

Consequences of Clot Formation and Hyphema Post-Internal Trabeculotomy for Glaucoma

PRCIS

Clot formation and hyphema following internal trabeculotomy represent distinct clinical entities. The eyes with clot formation exhibited a more pronounced postsurgical intraocular pressure spike, longer residual intracameral bleeding, and a higher risk of reoperation.

PURPOSE

The aim of this study was to investigate the consequences of clot formation and hyphema in the anterior chamber after internal trabeculotomy.

MATERIALS AND METHODS

In this retrospective interventional comparative study, we investigated the surgical outcomes of internal trabeculotomy in 142 eyes of 142 patients at Sensho-kai Eye Institute.

RESULTS

Concurrent clot formation and L≥2 hyphema (height of hyphema ≥1 mm) was observed in 22 eyes. In these cases, the postsurgical IOP was 29.3 mm Hg at 1 week, significantly higher than the 16.1 mm Hg in eyes that had L≥2 hyphema but without clot formation ( P =0.0002). However, the 1-week postsurgical IOP in L≥2 hyphema and clot (-) eyes, which measured 16.1 mm Hg was not significantly greater than that in L<2 hyphema and clot (-) eyes, which measured 18.7 mm Hg ( P =0.162). Thus, clot formation was identified as a significant factor contributing to high postsurgical IOP at 1 week. The resolution time for anterior chamber bleeding in eyes with concurrent clot formation and L≥2 hyphema was 12.3 days, longer than the 5.8 days observed in L≥2 hyphema eyes without clot formation ( P =0.016). Among the 22 eyes with concurrent L≥2 hyphema and clot formation, 8 required anterior chamber washout. Three of the 10 eyes that underwent washout necessitated additional trabeculectomy, a rate significantly higher than that in nonwashout eyes ( P <0.001).

CONCLUSIONS

After internal trabeculotomy, the sequelae of concurrent clot formation and L≥2 hyphema in the anterior chamber were more severe than those of simple hyphema without clots. Clot formation negatively affected postoperative IOP.

Transient anterior subcapsular vacuolar lens opacities after Tanito microhook trabeculotomy: report of six cases

OBJECTIVE

To present six cases exhibiting transient anterior subcapsular vacuolar lens opacities following early postoperative Tanito microhook trabeculotomy (TMH) performed by the same surgeon.

METHODS

Six patients who underwent lens-sparing TMH at Meizankai Shimizu Eye Clinic from November 2021 to May 2023, and developed anterior subcapsular vacuolar lens opacities postoperatively were reviewed. Detailed records of surgeries, follow-up findings were collected and reported.

RESULTS

In all six cases, anterior vacuolar subcapsular lens opacities were observed on the day after surgery, gradually decreasing without affecting visual acuity or contrast sensitivity. In all cases, without any specific interventions, the opacities disappeared by 21 months postoperatively.

CONCLUSION

Anterior subcapsular cataracts, characterized by a vacuolar appearance and transient existence, should be recognized as an early complication of ab interno glaucoma surgery, possibly linked to use of distributed ophthalmic viscosurgical devices and excessive anterior chamber irrigation leading to traumatic cataracts on the lens surface.

Minimally Invasive Direct Internal Cyclopexy in the Management of Goniotomy-Related Cyclodialysis Cleft with Hypotony Maculopathy

Introduction

Although ab-interno trabeculotomy-related (goniotomy-related) surgeries has a favorable safety profile, cyclodialysis cleft refractory to conservative management could occur, thereby requiring additional surgical treatment. External and, more recently, internal cycloplexy have been attempted to treat cyclodialysis clefts with hypotony maculopathy, however the traditional methods require conjunctival or scleral incisions and have been inappropriate for glaucoma patients who need to undergo future trabeculectomy. Therefore, we report two cases who underwent a novel reliable technique for suture fixation of the detached ciliary body onto the original scleral bed directly through the intraocular approach without conjunctival or scleral incision, minimally invasive direct internal cyclopexy, in the management of goniotomy-related cyclodialysis cleft with hypotony maculopathy.

Case Description

Goniotomy-related cyclodialysis cleft exceeded 45° and vision-threatening hypotony maculopathy was observed in two eyes in two patients with normal tension glaucoma and myopia gravis without a prior history of trauma who had undergone Kahook Dual Blade goniotomy combined with cataract surgery. The patients were followed conservatively for a while, however the cyclodialysis clefts and hypotony maculopathies did not resolve. Therefore, a 72-year-old man underwent minimally invasive direct internal cyclopexy on postoperative day 65 after the goniotomy, and another 67-year-old man underwent minimally invasive direct internal cyclopexy on postoperative day 149. In both cases, topical antibiotic and steroid eye drops were prescribed postoperatively. The cyclodialysis clefts were repaired successfully; however, the latter patient developed delayed-onset acute transient ocular hypertension 33 days after minimally invasive direct internal cyclopexy and required glaucoma medications. The hypotony maculopathies resolved approximately 3 months after suturing, and eventually visual acuity improved from preoperative levels and good intraocular pressure control was achieved in both. No further postoperative complications have been observed to date.

Conclusion

We successfully managed two cases of goniotomy-related cyclodialysis cleft with hypotony maculopathy using minimally invasive direct internal cyclopexy.

Evaluation of peripheral anterior synechia formation following gonioscopy-assisted transluminal trabeculotomy surgery

PURPOSE

To quantitatively assess the development of peripheral anterior synechia (PAS) formation rate and PAS locations on gonioscopic examination following gonioscopy-assisted transluminal trabeculotomy (GATT) surgery and investigate the surgical outcomes.

METHODS

A total of 35 eyes from 31 patients with open angle glaucoma who underwent GATT or combined GATT and phacoemulsification surgery were analyzed. Presence of PAS was assessed on gonioscopy in nasal, temporal, superior and inferior quadrants at months 1, 3 and 6 following surgery. Surgical outcomes were also noted.

RESULTS

Frequencies of PAS formation were 38.3%, 25.3%, 17.0% and 19.1% at postoperative 1 month, 34.0%, 26.4%, 17% and 22.6% at postoperative 3 months and 32.3%, 25.8%, 16.1% and 25.8% at postoperative 6 months, in nasal, temporal, superior and inferior quadrants, respectively. The highest amount of PAS involvement was 3 clock hours in the study which was identified only in nasal and inferior quadrants. Frequency of PAS formation did not significantly differ between nasal, temporal, superior and inferior quadrants at all time points (p > 0.05). No significant differences of mean IOP levels were observed between patients who developed PAS and who did not develop PAS at postoperative 1 month (p = 0.72), 3 months (p = 0.21) and 6 months (p = 0.59). The mean IOP and mean number of antiglaucoma medications decreased from 31.5 ± 7.2 mmHg and 3.6 ± 0.6 at baseline to 13.8 ± 3.1 mmHg and 1.6 ± 1.3 at postoperative 6 months, respectively (p < 0.001, for both). Cumulative success rate (95% confidence interval) was 74.3% (69.9-78.6%) at the end of the study. Mild to moderate degrees of hyphema occurred in all cases postoperatively.

CONCLUSION

Although PAS formation was observed to be relatively higher in nasal quadrant, PAS frequency was not statistically different between the angle quadrants.

Outcomes of Penetrating Canaloplasty in Childhood Glaucoma

PRCIS

Penetrating canaloplasty was safe and effective for the management of refractory childhood glaucoma.

PURPOSE

The purpose of this paper is to report the safety and efficacy of penetrating canaloplasty for the management of childhood glaucoma.

MATERIALS AND METHODS

This single-center prospective interventional case series enrolled 50 eyes of 32 patients with childhood glaucoma between July 2017 and July 2020. Penetrating canaloplasty to create direct communication between the anterior chamber and tensioning suture-dilated the Schlemm canal was performed through a trabecular meshwork ostium in the affected eyes. Preoperative and postoperative intraocular pressure (IOP), number of glaucoma medications, and procedure-related complications were recorded. Qualified and complete success was defined as IOP≥5 and ≤21 mm Hg with or without glaucoma medications, respectively.

RESULTS

A total of 43 eyes (86.0%) achieved 360 degrees catheterization of Schlemm canal and completed penetrating canaloplasty. The median age at surgery was 5 years (range, 10 d-17 y, mean 6.20±5.46 y). The mean IOP decreased from 33.11±10.89 mm Hg on 2 medications (median, range: 0-5) before surgery to 13.46±4.71 mm Hg on 0 medications (median, range:0-2) postoperatively at 12 months ( P <0.001). Complete and qualified success rates were 81.08% and 89.19%, respectively, at the 12-month follow-up. Hyphema (6/43, 13.95%) and a transient shallow anterior chamber with hypotony (5/43, 11.63%) were the most commonly observed early complications.

CONCLUSION

Penetrating canaloplasty demonstrated good safety and efficacy in eyes with childhood glaucoma, and may be considered an option for managing refractory childhood glaucoma.

Automated Focal Plane Merging From a Stack of Gonioscopic Photographs Using a Focus-Stacking Algorithm

Purpose

The purpose of this study was to investigate the utility of automated focal plane merging with the collection of gonio-photographs with different depths of field (DOF) using an established focus-stacking algorithm.

Methods

A cross-sectional study was conducted at Shimane University Hospital, Izumo, Japan. Sixteen eyes from 16 subjects from the glaucoma clinic were included in this study. Image processing was performed for the images of 16 eyes from 16 angle sector following the successful gonio-photography. The 256 sets of focus-stacked and best-focused images were prepared in random order and were compared for the DOF and informativeness to diagnose angle pathology by masked observers in each set as the subjective assessments. Moreover, the energy of the Laplacian (average |ΔI|), which is an indicator of image sharpness between the photographs with and without the focus-stacking processing was also analyzed with the Laplacian filter as the objective assessment.

Results

The automated image processing was successfully performed in all stacks of images. The significant deepening of DOF and improvement of informativeness achieved in 255 (99.6%) and 216 (84.4%) images (P < 0.0001 for both, sign test) and the energy of the Laplacian also significantly increased in 243 (94.9%) images (P < 0.0001, sign test).

Conclusions

Focal plane merging by the automated algorithm can make the gonio-images deeper focus compared with the paired best-focused images subjectively and objectively, which would be useful for angle pathological assessment in clinical practice.

Translational Relevance

Focal plane merging algorithm for the automated gonio-photography can facilitate the angle assessment by providing informative deep-focus image, which would be useful for glaucoma care.

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.

Non-inferiority of Microhook to Trabectome: Trabectome vs. ab interno Microhook Trabeculotomy Comparative Study (TramTrac Study)

PURPOSE

To elucidate the non-inferiority of ab interno microhook trabeculotomy (μTLO) using a recently developed reusable stainless spatula-type microhook device to incise the trabecular meshwork to trabectome (TOM) in terms of the 1-year postoperative outcomes of Japanese patients with glaucoma by means of propensity score analyses.

DESIGN

A multicenter retrospective cohort study.

PARTICIPANTS

We enrolled 553 and 392 patients who underwent TOM and μTLO, respectively, between January 2014 and March 2020 at 10 facilities.

METHODS

Logistic regression analysis was conducted to calculate the propensity score, which indicates the likelihood of treatment assignment (TOM or μTLO). We set the following factors as outcome-related covariates: age, sex, facility, glaucoma disease types, preoperative intraocular pressure (IOP), glaucoma drug score, mean deviation of the Humphrey visual field test and antithrombotic drug use, the presence or absence of combined cataract surgery, and incision range of trabecular meshwork (one or two quadrants). We analyzed four different methods (matching, inverse probability of treatment weighting (IPTW), stratification, and regression adjustment) using the propensity score. We set 15% as the non-inferiority margin based on previous trabectome meta-analysis results.

MAIN OUTCOME MEASURES

The primary outcome was surgical success at 1 year postoperatively. We defined surgical success as satisfying all three criteria: (1) IOP within 5-21 mmHg; (2) IOP reduction of ≥20% from preoperative IOP; and (3) no additional glaucoma surgery.

RESULTS

The 95% confidence interval of risk difference of surgical failure in μTLO in reference to TOM was -12.1 to +9.5% in matching, -12.7 to +11.1% in IPTW, -12.2 to +7.0 in stratification, and -9.7 to +8.1% in regression adjustment, all of which fell within the predetermined non-inferiority margin of 15%.

CONCLUSIONS

Surgical success of μTLO at 1-year postoperatively was not inferior to that of TOM.

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.