Turn Back Elevation of Once Reduced IOP After Trabeculotomy Ab Externo and Kahook Dual Blade Surgeries Combined with Cataract Surgery

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.

Development and Application of a New T-shaped Internal Trabeculotomy Hook (T-hook)

PURPOSE

We introduce a newly designed T-shaped internal trabeculotomy hook and compare its surgical outcomes with those of Kahook dual blade (KDB) surgery.

PATIENTS AND METHODS

One eye each of seventeen and sixty-one patients underwent T-hook and KDB surgeries, respectively. Post-surgical intraocular pressure (IOP), medications, visual acuity, and prevalence of IOP spikes and hyphema were compared between the two cohorts.

RESULTS

The utility of the T-hook was excellent and enabled the easy opening of the Schlemm's canal. The pre-surgical IOP of 25.6 ±7.5 mmHg in the T-hook cohort decreased to 14.1 ± 4.3 (-41.2% reduction) and 15.0 ± 3.1mmHg (-39.3% reduction) at 3 (P<0.001) and 6 months (P=0.003), respectively. Pre-surgical medications of 2.8 decreased to 2.3 and 2.0 medications, respectively, at 3 and 6 months. The best-corrected visual acuity (BCVA) improved from the pre-surgical logarithm of the minimum angle resolution (logMAR) of 0.148 to -0.012 at three months (P=0.036,). While the pre-surgical IOP of 24.9±4.3 mmHg in the KDB cohort decreased to 16.5±5.7 mmHg (-35.5%, P<0.001) and 16.1±3.4 mmHg (-33.5%, P<0.001) at 3 and 6 months, respectively. Reduction in medications at 3- and 12-month timepoints (from 2.8 to 1.7 and 1.7, respectively; P<0.001) and improvement in BCVA at three months (from 0.106 to -0.025 logMAR, P<0.001) were also significant. There was no difference between the T-hook and KDB cohorts in terms of the pre-surgical IOP (P=0.15) and post-surgical IOP at 1 (P=0.27), 3 (P=0.17), 6 (P=0.47), and 12 months (P=0.11, Mann-Whitney U-test). The prevalence of a post-surgical IOP spike in the T-hook and KDB cohorts was 41.2% and 47.5%, and that of post-surgical hyphema was 17.6% and 26.2%, respectively.

CONCLUSION

The novel T-hook was easy to use and was as useful as the KDB device in performing internal trabeculotomy.

Ab Interno Goniotomy with the Kahook Dual Blade in a Monocular Patient with Mucous Membrane Pemphigoid and Refractory Open Angle Glaucoma: A Case Report

Purpose

To describe the case of a monocular patient with ocular mucous membrane pemphigoid (MMP) and open angle glaucoma refractory to medical treatment, who was successfully managed with ab interno goniotomy at the time of cataract surgery.

Methods

A 63-year-old woman with a history of severe MMP presented with exacerbation of the disease in both eyes. Vision was 20/80 in the right eye and light perception in the left eye. Symblepharon formation, trichiasis and forniceal foreshortening were present in the right eye, while the cornea of the left eye was completely conjunctivalized. Following aggressive systemic immunosuppressive therapy with corticosteroids and cyclophosphamide, the disease was brought under control. However, the patient developed a mature cataract and high intraocular pressure (IOP) of 28 mmHg on maximal medical therapy. Due to the high risk of ocular MMP exacerbation with glaucoma filtration surgery, the decision was made to proceed with cataract extraction combined with ab interno goniotomy with the Kahook Dual Blade.

Results

There were no intraoperative complications. The IOP has remained in the 12–14 mmHg range without any topical glaucoma medications over a total follow up of 3.5 years.

Conclusion

Ab interno goniotomy using the Kahook Dual Blade can significantly reduce IOP and medication burden in MMP cases, where any type of conjunctival incisional surgery could induce disease flare up. In this case, it represented a safe and effective surgical procedure for ocular MMP with concomitant refractory open angle glaucoma.

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.