Fellow-Eye Comparison between Phaco-Microhook Ab-Interno Trabeculotomy and Phaco-iStent Trabecular Micro-Bypass Stent

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.

Comparison of 1-year effectiveness between phaco-microhook ab-interno trabeculotomy and phaco-iStent trabecular micro-bypass stent in primary open-angle glaucoma with low-teen intraocular pressure

PURPOSE

To investigate the surgical effectiveness of combined cataract surgery with microhook ab-interno trabeculotomy (phaco-µLOT) or iStent trabecular micro-bypass stent (phaco-iStent) in eyes with primary open-angle glaucoma (POAG) and preoperative intraocular pressure (IOP) controlled below 15 mmHg (low-teen IOP).

METHODS

This retrospective cohort study included consecutive patients with POAG and low-teen IOP who underwent phaco-µLOT or phaco-iStent as their initial glaucoma surgery and were followed up for 1 year postoperatively. Surgical failure was defined as the inability to achieve the following criteria twice in a row: (A) IOP of 6-15 mmHg with over 20% IOP reduction; (B) IOP of 6-12 mmHg with over 20% IOP reduction.

RESULTS

A total of 75 eyes from 75 subjects were included, with 48 in the phaco-µLOT group and 27 in the phaco-iStent group. The mean preoperative IOP and number of antiglaucoma medications were 13.1 ± 2.1 mmHg and 3.4 ± 0.9 in the phaco-µLOT group, and 12.6 ± 2.0 mmHg and 2.5 ± 1.2 in the phaco-iStent group, respectively. The number of antiglaucoma medications was significantly reduced to 2.5 ± 0.9 (phaco-µLOT) and 2.0 ± 1.1 (phaco-iStent) at 1-year postoperatively (all p < 0.05). For criteria A and B, the survival rates were significantly higher in the phaco-µLOT group than in the phaco-iStent group (all p < 0.01).

CONCLUSION

Both phaco-µLOT and phaco-iStent hold promise in reducing the need for antiglaucoma medications in POAG eyes with low-teen IOP. Phaco-µLOT may be more effective than phaco-iStent in controlling IOP.

KEY MESSAGES

What is known Minimally invasive glaucoma surgeries (MIGS) procedures target the pressure gradient pathways in patients with higher preoperative intraocular pressure (IOP) levels, however, evidence on their effectiveness in normotensive glaucoma patients remains limited. What is new Combined cataract surgery with microhook ab-interno trabeculotomy (phaco-µLOT) or iStent trabecular micro-bypass stent (phaco-iStent) significantly reduced the number of antiglaucoma medications in primary open-angle glaucoma (POAG) eyes with preoperative IOP controlled below 15 mmHg (low-teen IOP). Phaco-µLOT may be more effective than phaco-iStent in controlling IOP. These procedures should be limited to reducing the number of antiglaucoma medications used, as they did not significantly reduce the postoperative IOP in POAG eyes with low-teen IOP.

Quantification of Postoperative Inflammation in Laser and Surgical Procedures for Glaucoma with Laser Flare Photometry: A Review of the Literature

PURPOSE

To review the application of laser flare photometry (LFP) in the objective quantification of aqueous flare (anterior chamber inflammation) post laser and surgical procedures for glaucoma.

METHODS

A search was undertaken using the following: PubMed (all years), the Web of Science (all years), Ovid MEDLINE (R) (1980 to 30 March 2023), Ovid MEDLINE (R) Daily Update 30 March 2023, MEDLINE and MEDLINE non-indexed items, Embase (1980-2021, week 52), Ovid MEDLINE (R) and Epub Ahead of Print, in-Process & Other Non-Indexed Citations and Daily (1980 to 30 March 2023), CENTRAL (including Cochrane Eyes and Vision Trials Register), metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrial.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (www.who.int/ictrp/search/en). Search terms included "aqueous flare," "anterior chamber inflammation," "tyndallometry," "laser flare photometry" combined with "laser," "iridotomy," "trabeculoplasty," "cataract surgery," "phacoemulsification," "glaucoma surgery," "minimally invasive glaucoma surgery," "trabeculectomy," "aqueous shunt," "glaucoma drainage" and "cyclophotocoagulation."

RESULTS

The majority of studies utilizing laser flare photometry in grading flare have been post laser trabeculoplasty. The degree of flare produced varies according to the type of glaucoma laser or surgery performed, with filtration procedures and glaucoma drainage devices having marked and prolonged detectable levels. Aqueous flare in cyclodestructive procedures positively correlated with intraocular pressure (IOP) reduction.

CONCLUSION

In comparison to clinician grading, laser flare photometry provides a more objective measure of post-surgical inflammation in eyes that have undergone laser and surgery for glaucoma. Further research is warranted into how this instrument can be utilized to identify eyes at high risk of failure and other adverse outcomes after glaucoma surgery.

Prediction of MIGS outcomes on second eyes using first eyes' response

To evaluate how well outcomes following cataract extraction and microinvasive glaucoma surgery in one eye predict outcomes in sequential second eye. Retrospective study of 78 patients who underwent cataract extraction and microinvasive glaucoma surgery in both eyes. Linear regressions using Pearson correlation coefficients were used to evaluate correlations in intraocular pressure and glaucoma medication change between eyes. Multivariable logistic regression models were used to evaluate the associations between first-eye variables and the likelihood of second-eye surgical success at 6 months. Surgical success was defined as meeting target intraocular pressure without additional medications compared to baseline or secondary surgical interventions. Baseline ocular characteristics were comparable between fellow eyes, with the majority having mild glaucoma. Intraocular pressure changes between fellow eyes at 6 months were modestly correlated between eyes (R = 0.48; P < .001). Changes in glaucoma medications were strongly correlated between eyes at all time points, and month 6 demonstrated the most significant correlation (R = 0.80; P < .001). First and second eye cohorts achieved 82% and 83% surgical success. Multivariate analysis for predictive factors of successful second eye surgery showed patients with successful first eye surgery at 6 months were significantly more likely to have successful second eye surgery (odds ratio, 20.67; P < .001). Reductions in intraocular pressure and glaucoma medications at 6 months following surgery in first eyes are correlated to second eye reductions. Successful surgical outcomes at 6 months following first eye surgeries are strongly associated with successful sequential second eye outcomes.

Fellow-Eye Comparison between Phaco-Tanito Microhook Trabeculotomy and Phaco-iStent Inject W

This study aims to compare the surgical efficacy and safety of the Tanito microhook trabeculotomy (TMH-CE) and iStent inject W (Inject-CE) when performed in combination with cataract surgery on the eyes of glaucoma patients. A total of 78 glaucomatous eyes from 39 participants were retrospectively analyzed. Intraocular pressure (IOP), the number of antiglaucoma medications, best-corrected visual acuity (BCVA), anterior chamber flare (ACF), and corneal endothelial cell density (CECD) were all evaluated preoperatively and at multiple postoperative time points. The preoperative IOP was significantly higher in the TMH-CE (19.6 ± 6.7 mmHg) than in the Inject-CE (15.7 ± 3.8 mmHg) (p < 0.0001). At the 12-month follow-up, reductions in IOP and the number of medications were more pronounced in the TMH-CE (6.6 mmHg, 27.6% and -1.1, respectively) group than Inject-CE (2.7 mmHg, 12.4% and -0.7, respectively) (p < 0.0001 and p = 0.0034), while the IOP and medication-number levels were identical between TMH-CE (13.0 ± 3.3 mmHg and 1.3 ± 0.9, respectively) and Inject-CE (12.9 ± 2.6 mmHg and 1.9 ± 0.9, respectively) (p = 0.88 and p > 0.99, respectively). The TMH-CE group exhibited a higher ACF, a higher frequency of layered hyphema, and a greater anterior chamber floating red blood cells score in the early postoperative periods. Despite these differences, the changes in BCVA, ACF, and CECD were equivalent between the two groups in later follow-up periods. TMH-CE provides a more significant IOP reduction and medication-number reduction compared to Inject-CE, while Inject-CE shows quicker BCVA recovery. This study provides valuable insights for ophthalmologists choosing the most suitable surgical approach for glaucoma and cataract patients.

Comparison of surgical outcomes between iStent inject W implantation and microhook ab interno trabeculotomy in combination with phacoemulsification in primary open-angle glaucoma patients

Purpose

To examine primary open-angle glaucoma patients after undergoing combined cataract surgery with microhook ab interno trabeculotomy (μLOT-Phaco) or iStent inject W implantation (iStent-Phaco), and then evaluate the surgical outcomes after a minimum of 6 months of follow-up.

Methods

Between October 2020 and July 2022, 39 μLOT-Phaco eyes and 55 iStent-Phaco eyes that underwent surgery were evaluated in this retrospective, multicenter comparative case series. Data that included preoperative and postoperative intraocular pressure (IOP), number of glaucoma medications, and occurrence of complications were collected from medical records and then examined. Surgical failure was defined as patients exhibiting a < 20% reduction in the preoperative IOP or an IOP > 18 mmHg on two consecutive follow-up visits, or when patients were required to undergo reoperation. Success rates were determined based on a Kaplan-Meier survival analysis.

Results

At 3, 6 and 12 months postoperatively, there was a significant postoperative reduction in the IOP (p < 0.001) and in the medications scores (p < 0.001) for both of the groups. In the μLOT-Phaco and iStent-Phaco groups, the probabilities of success at 6 and 12 months were 55.3 and 45.5%, and 48.4 and 45.5% (p = 0.38; log-rank test), respectively. In the iStent-Phaco group, there was a significant decrease in the hyphema.

Conclusion

Comparable surgical outcomes occurred for both the μLOT and iStent inject W procedures.

A case of two connected stents deployed during iStent inject W surgery

BACKGROUND

We report a case with two connected stents ejected simultaneously during an iStent inject W surgery, a modified second-generation iStent Trabecular Micro-Bypass System.

CASE PRESENTATION

A 57-year-old woman with primary open-angle glaucoma underwent a combined cataract and iStent inject W surgery in her left eye. After the trabecular meshwork/Schlemm's canal was pierced by the trocar of injector, the delivery button was pressed a first time, but the stent was not ejected. After the button was pressed a second time, connected two stents were ejected. After removing the dislocated stents from the anterior chamber, two stents were implanted into the desired places using another injector. Except for mild hyphema, no postoperative complication occurred. Stereomicroscopic observation showed that the two stents were connected by a broken trocar shaft. An X-ray showed that the trocar shaft was broken at the part referred to as the "sprayed trocar". Scanning electron microscopy showed that the surface features of the broken trocar and trocar tip represented tensile failure.

CONCLUSIONS

Although rare, considering that the damage was seen at the structurally weak part (i.e., sprayed trocar), the same phenomenon can happen. For patient safety, surgeons are recommended to inspect the device when the deployment of either the first or second stent is unsuccessful during the iStent inject surgery.

Roles of Toric intraocular Lens implantation on visual acuity and astigmatism in glaucomatous eyes treated with iStent and cataract surgery

Background

To assess the efficacy of toric intraocular lenses (IOLs) in combined cataract and minimally invasive glaucoma surgery (MIGS), visual and refractive outcomes were compared between eyes implanted with non-toric and toric IOLs during iStent triple procedures.

Methods

In this retrospective study, open angle glaucoma eyes with preexisting corneal astigmatism of -1.5 diopter (D) or more and implanted with non-toric (n = 9) or toric (n = 9) IOLs were included. The main outcome measures were the intergroup difference in the uncorrected visual acuity (UCVA) and refractive astigmatism at 3 months postoperatively.

Results

Preoperatively, the logarithm of the minimum angle of resolution (logMAR) UCVAs and refractive astigmatism were equivalent between the groups. Postoperatively, the logMAR UCVA (non-toric, 0.45 ± 0.31; toric, 0.14 ± 0.15; P = 0.021) was significantly better and the refractive astigmatism (non-toric, -2.03 ± 0.63 D; toric, -0.67 ± 0.53 D; P = 0.0014) significantly less in the toric group. The toric group had postoperative improvements in the logMAR UCVA (-0.21, P = 0.020) and refractive astigmatism (+ 1.72 D, P = 0.0039). Vector analyses showed the postoperative centroid magnitude and confidence eclipses of refractive astigmatism was less in the toric group (0.47 D at 173°±0.73D) than the non-toric group (1.10 D at 2°±1.91D). Postoperatively, 78% of eyes in the toric group had 1.0 D or less refractive astigmatism compared with 11% in the non-toric group. Surgically induced astigmatism (non-toric, 0.18 D at 65°; toric, 0.29 D at 137°) did not differ between groups.

Conclusion

Use of toric IOLs is a reasonable option for better visual outcomes when the combined cataract and iStent surgery is performed in glaucomatous eyes with corneal astigmatism.

Corneal Endothelial Cell Loss in Patients After Minimally Invasive Glaucoma Surgery: Current Perspectives

Minimally invasive glaucoma surgery (MIGS) is a rapidly expanding category of surgical glaucoma treatment options that offer a superior safety profile compared with traditional approaches for reducing intraocular pressure. However, MIGS may cause corneal endothelial cell loss; therefore, it has been receiving increasing attention. This systematic review aimed to evaluate and compare the rate and degree of corneal endothelial loss after MIGS. First, this paper presents an overview of the theoretical effectiveness of MIGS, the fundamental aspects regarding the roles of endothelial cells, and the effect of cataract surgery on the quality and count of endothelial cells. Further, we detail the various surgical techniques involved in MIGS, the development of these techniques over the time, and clinical aspects to consider with respect to the endothelial cell count. We discuss in detail the COMPASS-XT study, which was based on data collected over 5 years, reported that withdrawal of the CyPass Micro-Stent (Alcon Laboratories) yielded increased corneal endothelial cell loss. Generally, MIGS procedures are considered safe, with the incidence of complications ranging from 1% to 20% depending on the surgery type; however, there is still need for studies with longer follow-up. Thus, an adequate count of endothelial cells in the central cornea portion is recommended as necessary for candidate patients for MIGS.

Endothelial cell loss associated with minimally invasive glaucoma surgery

PURPOSE OF REVIEW

Minimally invasive glaucoma surgery (MIGS) represents a safer, albeit moderately effective surgical option for intraocular pressure control. However, the CyPass Micro-Stent (Alcon Laboratories) was withdrawn from the market in 2018 as the COMPASS-XT study demonstrated greater cornea endothelial cell (CEC) loss in patients who received the CyPass Micro-Stent with phacoemulsification compared with phacoemulsification alone. This led to the increased attention on MIGS-associated CEC loss and thus, this review will summarise the recent, available evidence on MIGS-associated CEC loss.

RECENT FINDINGS

Prospective clinical trials and retrospective observational studies published between 2011 and 2021 reported a wide range of 12 month CEC loss from 'insignificant', and up to 14.6%, for phacoemulsification combined with various MIGS procedures. Recent clinical trials over the same time period reported CEC loss of 12.8-15.2% associated with phacoemulsification alone.

SUMMARY

Apart from the CyPass Micro-Stent clinical trial, no other studies on combined phacoemulsification with MIGS that is 'phaco-plus' procedures have reported a higher short-term CEC loss compared with phacoemulsification alone. However, studies that specifically examine postprocedural CEC loss following phacoemulsification compared to 'phaco-plus' procedures over a longer follow-up period are required.

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.