Histologic Analysis of Trabecular Meshwork Obtained From Kahook Dual Blade Goniotomy

Histopathologic correlates of trabecular meshwork in microincisional trabeculectomy

PURPOSE

To report the histopathologic correlates of trabecular meshwork (TM) specimens procured by microincisional trabeculectomy (MIT) for different severities of glaucoma (early glaucoma: visual field mean deviation [MD] <-6 dB, moderate glaucoma: MD from - 6 to - 12 dB, and advanced glaucoma: MD <-12 dB).

METHODS

TM specimens from four patients undergoing MIT with or without cataract surgery were analyzed by routine histopathology for structural changes. The number of cells, the number of cells with spindle-shaped nuclei suggestive of epithelial-mesenchymal transformation (EMT), and the distance between the trabecular beams were calculated using different tools on freely available ImageJ software using the line or pint/count tool.

RESULTS

The TM specimens procured from two early and two advanced glaucoma cases showed decreasing cellularity and decreased compact arrangement of the trabecular beams in severe disease stages. The number of cells and preserved architecture in all four specimens were evident, with > 50 cells being present per section in all four cases despite the glaucoma being of advanced disease stage in two patients.

CONCLUSION

The TM specimens obtained from MIT can be utilized for downstream analysis using different molecular methods for studying the molecular events in the tissue from early to severe glaucoma.

Randomised clinical trial for morphological changes of trabecular meshwork between Kahook dual-blade goniotomy and ab interno trabeculotomy with a microhook

We demonstrated whether the difference of trabecular meshwork remodeling occur depending on the incisional cross-sectional area by comparing Kahook dual-blade goniotomy (KDB) and ab interno trabeculotomy with a microhook. Phakic eyes with primary open-angle or exfoliative glaucoma were randomised into a KDB or a microhook group. The primary outcome was an incisional cross-sectional area quantified by anterior segment optical coherence tomography. In subgroup analysis, the number of patients with the unidentifiable incisional area was compared between the groups. Secondary outcomes were the rate of intraocular pressure changes, the laser flare metre values, corneal endothelial cell densities, the number of glaucoma medications, the usage rate per glaucoma medication type and postoperative complications between the two groups. A total of 29 eyes in 29 patients in the KDB and microhook group were included respectively, with an overall mean age of 72.6 ± 8.1 years. The incisional cross-sectional area of the KDB group was significantly larger at 1 week and at 1, 6 and 12 months (p < 0.01) postoperatively. The number of patients with the nonidentified incisional area was higher at 1, 6 and 12 months postoperatively (p ≤ 0.03) in the microhook group. The flare values in the KDB group were higher than those in the microhook group at 12 months postoperatively (p = 0.02). No significant differences were observed in other secondary outcomes. Incisional cross-sectional area remains larger in eyes treated with KDB goniotomy than in those treated with ab interno trabeculotomy with the microhook, whereas KDB goniotomy did not have an advantage in controlling intraocular pressure postoperatively.Trial registration: UMIN000041290 (UMIN, University Hospital Medical Information Network Clinical Trials Registry of Japan; date of access and registration, 03/08/2020).

Tissue-engineered anterior segment eye cultures demonstrate hallmarks of conventional organ culture

BACKGROUND

Glaucoma is a blinding disease largely caused by dysregulation of outflow through the trabecular meshwork (TM), resulting in elevated intraocular pressure (IOP). We hypothesized that transplanting TM cells into a decellularized, tissue-engineered anterior segment eye culture could restore the outflow structure and function.

METHODS

Porcine eyes were decellularized with freeze-thaw cycles and perfusion of surfactant. We seeded control scaffolds with CrFK cells transduced with lentiviral vectors to stably express eGFP and compared them to scaffolds seeded with primary TM cells as well as to normal, unaltered eyes. We tracked the repopulation behavior, performed IOP maintenance challenges, and analyzed the histology.

RESULTS

Transplanted cells localized to the TM and progressively infiltrated the extracellular matrix, reaching a distribution comparable to normal, unaltered eyes. After a perfusion rate challenge to mimic a glaucomatous pressure elevation, transplanted and normal eyes reestablished a normal intraocular pressure (transplanted = 16.5 ± 0.9 mmHg, normal = 16.9 ± 0.9). However, eyes reseeded with eGFP-expressing CrFK cells could not regulate IOP, remaining high and unstable (27.0 ± 6.2 mmHg) instead.

CONCLUSION

Tissue-engineered anterior segment scaffolds can serve as readily available, scalable ocular perfusion cultures. This could reduce dependency on scarce donor globes in outflow research and may allow engineering perfusion cultures with specific geno- and phenotypes.

Outcomes and risk factors for ab interno trabeculotomy with a Kahook Dual Blade

PURPOSE

To verify the surgical results and risk factors for ab interno trabeculotomy using a Kahook Dual Blade (KDB-LOT) in patients with various glaucoma types.

METHODS

This study was a retrospective case series of 205 eyes that underwent KDB-LOT. For Kaplan-Meier survival analysis, criterion A was defined as a ≤ 20% reduction in intraocular pressure (IOP) from baseline. Criteria B, C, and D were IOPs of ≤ 21, 18, and 15 mmHg, respectively. The Cox proportional hazard (CPH) model investigated prognostic factors.

RESULTS

The mean (SD) IOP decreased from 24.7 (7.98) to 17.6 (4.80) mmHg in all cases, from 21.3 (6.88) to 17.8 (3.52) mmHg in primary open-angle glaucoma (POAG), from 25.4 (7.32) to 17.1 (4.65) mmHg in exfoliation glaucoma, from 30.6 (8.88) to 17.8 (8.29) mmHg in uveitic glaucoma, and from 30.8 (7.29) to 17.3 (0.83) mmHg in steroid-induced glaucoma at 1 year after KDB-LOT. The Kaplan-Meier survival analysis showed that patients with POAG had the best prognosis under criteria B and C, and the 1-year survival rate in patients under criterion D was less than 35% for any disease type. CPH analysis revealed that age and KDB-LOT with phacoemulsification were good prognostic factors. Risk factors for surgical failure were previous cataract surgery, selective laser trabeculoplasty, and postoperative peripheral anterior synechiae.

CONCLUSION

KDB-LOT was effective in treating patients with several glaucoma types but showed difficulty in pushing IOP below 15 mmHg. Prognostic factors should be considered when making decisions regarding surgical indications.

Predictive Factors of Outcomes in Kahook Dual Blade Excisional Goniotomy Combined with Phacoemulsification

Aim

To identify factors that were significant predictors of Kahook Dual Blade (KDB) excisional goniotomy outcomes.

Materials and methods

One hundred and thirty-two eyes from 99 adult glaucoma patients who underwent combined KDB and phacoemulsification (KDB-phaco) with a minimum 6-month follow-up were assessed for baseline patient characteristics to determine correlation to the success of KDB-phaco at 6 and 12 months postoperatively. Success was defined as ≥20% intraocular pressure (IOP) reduction or ≥1 medication reduction as well as IOP ≤18 mm Hg without any additional IOP-lowering procedures after KDB-phaco.

Results

63.6% (84/132) and 46.1% (41/89) of cases were successful at the 6- and 12-month follow-ups, respectively. KDB-phaco reduced patient's preoperative IOP (in mm Hg) from 17.6 ± 4.6 to 14.9 ± 3.2 at 6 months (15.3%, p < 0.001) and 15.4 ± 4.7 at 12 months (12.5%, p = 0.001). KDB-phaco reduced patient's preoperative IOP-lowering medications from 2 ± 1.2 to 1.1 ± 1.2 at 6 months (45%, p < 0.001) and 1.32 ± 1.3 at 12 months (34%, p < 0.001). At 6 months, patients on >1 IOP lowering medication had a greater chance of meeting our success criteria (p = 0.037). Visually significant postoperative hyphema was not associated with the use of anticoagulation (p = 0.943) but was significantly associated with postoperative day 1 IOP ≤ 10 mm Hg (p = 0.011).

Conclusion

Patients who underwent KDB-phaco significantly reduced their IOP and medication burden at both 6 and 12 months compared with their baseline preoperative values. KDB-phaco outcome was associated with higher baseline IOP-lowering medications and increased rate of hyphema was associated with lower postoperative day 1 IOP, regardless of anticoagulation status. Age, ethnicity, prior laser trabeculoplasty, type and severity of glaucoma, and baseline preoperative IOP were not associated with surgical success.

Clinical significance

Patients with a higher number of baseline medications may experience a greater probability of success following KDB-phaco.

How to cite this article

Pratte EL, Cho J, Landreneau JR, et al. Predictive Factors of Outcomes in Kahook Dual Blade Excisional Goniotomy Combined with Phacoemulsification. J Curr Glaucoma Pract 2022;16(1):47-52.

A Review of Excisional Goniotomy Performed with the Kahook Dual Blade for Glaucoma Management

Aim

To review the published literature describing clinical outcomes of excisional goniotomy using the Kahook Dual Blade (KDB) for the management of glaucoma.

Background

A family of less invasive glaucoma procedures-including excisional goniotomy with the KDB-has been developed to provide moderate reductions in intraocular pressure and/or medication burden in eyes with therapeutic needs that may not warrant the risks associated with more traditional procedures such as trabeculectomy and tube-shunt implantation. This review's goal is to synthesize the existing literature into a compendium of excisional goniotomy's indications, technique, efficacy and safety outcomes, and optimal place in glaucoma management.

Review results

Excisional goniotomy with the KDB effectively lowers IOP and reduces the medication burden in eyes with POAG and other forms of glaucoma across the spectrum of both baseline IOP and disease severity. The procedure exhibits a safety profile that is on par with other angle-based surgical interventions and enhanced safety compared to filtration procedures. It can be performed by comprehensive ophthalmologists as well as glaucoma specialists. This procedure as a standalone operation delivers IOP reductions consistent with filtration surgery, and in combination with cataract surgery delivers both IOP and medication reductions at least as great as other minimally invasive procedures.

Conclusion

Given the broad base of evidence supporting its use in a wide variety of clinical scenarios, excisional goniotomy with the KDB can play a meaningful role in the achievement of patient-specific glaucoma therapy goals.

Clinical significance

These aggregate findings support the efficacy and safety of excisional goniotomy with the KDB and clarify the patient profiles best suited for this procedure.

How to cite this article

Dorairaj S, Radcliffe NM, Grover DS, et al. A Review of Excisional Goniotomy Performed with the Kahook Dual Blade for Glaucoma Management. J Curr Glaucoma Pract 2022;16(1):59-64.

Sampling trabecular meshwork using TrabEx

Background

To report sampling of the trabecular meshwork using the TrabEx+ (MicroSurgical Technology, Redmond, Washington, USA) device in ab interno trabeculectomy. Specifically, this series focusses upon preservation of the trabecular meshwork architecture for assessment of glaucomatous features using common histopathological techniques.

Patients

This series features six glaucomatous eyes undergoing TrabEx+ with or without cataract surgery. Three patients had primary open angle glaucoma and the remaining had pigment dispersion glaucoma, ocular hypertension or uveitic glaucoma. Four eyes had simultaneous cataract surgery.

Methods

Trabecular meshwork was excised using the TrabEx+ device and retrieved using vitreoretinal forceps. The samples were then processed into formalin-fixed paraffin-embedded 4 micron tissue segments and stained with haematoxylin and eosin, periodic acid–Schiff and elastin Van Gieson. Collagen IV was labelled using immunohistochemistry for the purpose of identifying the basement membrane of trabecular beams.

Results

Presence of trabecular meshwork was confirmed in five of the six samples taken. One of six samples consisted of blood only, but this was expected following early termination of the procedure due to patient restlessness. In the five positive cases trabecular beams with associated trabecular meshwork cells were identified on hematoxylin-eosin and periodic acid–Schiff staining. The beams retained their lamellar structure. The basement membrane underlying the trabecular cells was evident in three specimens, whilst two specimens were of insufficient size for collagen IV labelling.

Conclusions

This case series illustrates that TrabEx+ can be utilised to successfully retrieve trabecular meshwork samples with sufficient architectural perseveration of the tissue to enable histopathological and laboratory analysis.

Corneal Endothelial Cell Changes After Phacoemulsification Combined with Excisional Goniotomy with the Kahook Dual Blade or iStent: A Prospective Fellow-Eye Comparison

Purpose

To characterize changes in endothelial cell density and morphology following phacoemulsification combined with either excisional goniotomy with the Kahook Dual Blade (KDB-phaco) or first-generation iStent trabecular microbypass implantation (iStent-phaco).

Setting

A single clinical practice.

Methods

Twenty-one adult subjects from one center with visually significant cataract and mild-moderate open-angle glaucoma underwent KDB-phaco or iStent-phaco in one eye and the alternate procedure in the fellow eye as part of a prospective, multicenter, randomized trial. Specular microscopy and pachymetry were performed before and 6–29 months after surgery. Parameters analyzed included change from baseline of endothelial cell density (ECD), the coefficient of variation (CV), the percent of hexagonal cells (%HEX), and central corneal thickness (CCT).

Results

Baseline ECD, CV, %HEX, and CCT were similar between groups. A mean (standard deviation) of 18.2 (5.8) months postoperatively (range 12.5–28.7 months), the change from baseline in ECD was −90 ± 226 cells/mm² (−3.4%) in KDB-phaco eyes (p=0.083) and −239 ± 247 cells/mm² (−9.0%) in iStent-phaco eyes (p<0.001); the change in iStent-phaco eyes was significantly greater than in KDB-phaco eyes (p=0.013). The magnitude of Endothelial Cell Loss (ECL) was not correlated with length of postoperative follow-up time in either group. No significant differences in change from baseline in CV, %HEX, or CCT were noted with the exception of a decrease in %HEX in iStent-phaco eyes (p=0.017). No eyes manifested corneal edema, decompensation, or other cornea-related complications.

Conclusion

Both KDB-phaco and iStent-phaco are associated with postoperative ECL, with iStent-phaco producing significantly greater ECL than KDB-phaco. The clinical significance of these findings is unclear, and future studies are warranted to more robustly characterize long-term effects of glaucoma surgical procedures—with and without permanent implants—on ECD and corneal health and to develop evidence-based guidelines for the pre- and post-operative evaluation of corneal health in eyes undergoing glaucoma surgery.