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.

iStent Trabecular Micro-Bypass Stent Implantation with Cataract Surgery in a Japanese Glaucoma Population

Introduction

This study assesses two-year efficacy and safety following implantation of a single trabecular micro-bypass stent (iStent^®) with concomitant phacoemulsification cataract surgery in Japanese patients with open-angle glaucoma (OAG).

Materials and Methods

This retrospective, consecutive case series included eyes that underwent iStent implantation with phacoemulsification and were followed for 24 months postoperative. Efficacy and safety measures included intraocular pressure (IOP), number of glaucoma medications, adverse events, secondary surgeries, visual fields, and endothelial cell counts.

Results

Of 73 operated eyes, 53 eyes had 24 months of follow-up and are analyzed. Diagnoses included primary open-angle glaucoma (POAG, n=25), normal-tension glaucoma (NTG, n=16), and pseudoexfoliative glaucoma (PXG, n=12). At 24 months, mean IOP reduced by 18% to 13.6±3.0 mmHg versus 16.5±3.4 mmHg preoperatively (p<0.0001), and mean medication number reduced by 81% to 0.37±0.74 versus 1.96±0.98 preoperatively (p<0.0001). The percentage of medication-free eyes was 77% versus 0% preoperatively, and 81% of eyes had IOP ≤15 mmHg versus 42% preoperatively. Results were similarly favorable across glaucoma subtypes (POAG, NTG, PXG). Notably, mean IOP in NTG eyes decreased to 12.8±1.4 mmHg from 14.4±3.0 mmHg preoperatively (p=0.03), and medications decreased by 87% to 0.31±0.70 versus 2.38±0.72 preoperatively (p<0.0001). At 24 months, 81% of NTG eyes were medication-free (versus 0% preoperatively); 2 NTG eyes (13%) were on ≥2 medications (versus 100% preoperatively). Throughout the follow-up, visual fields and endothelial cell counts remained stable; 1 eye (1.9%) underwent filtration surgery.

Discussion

Favorable safety and significant IOP and mediation reductions were achieved through two years following iStent implantation with phacoemulsification in a Japanese population. These gains were achieved across all glaucoma subtypes (including POAG, NTG, PXG).

Conclusion

This real-world study supports the viability of iStent implantation to treat Japanese patients with glaucoma and shows that the benefits extend to those with NTG or PXG in addition to POAG.

Quality of Life After Combined Cataract and Minimally Invasive Glaucoma Surgery in Glaucoma Patients

Purpose

To determine the quality of life (QOL) in glaucoma patients undergoing combined cataract and minimally invasive glaucoma surgery from various perspectives ranging from personal, social, occupational life, and economic status.

Settings and Design

A cross-sectional study design at King Fahd Hospital of the University, Khobar, Saudi Arabia.

Methods

Patients undergoing phacoemulsification in conjunction with various forms of minimally invasive glaucoma surgery (MIGS) for each patient, including either Kahook Dual Blade (KDB) goniotomy, iStent, iStent inject and gonioscopy-assisted transluminal trabeculotomy (GATT), were included in the study between 2018 and 2019. Data were collected through a self-administered questionnaire based on the Visual Function Questionnaire (VFQ-25) for the 25-item National Eye Institute.

Results

The study included 93 eyes of 78 patients (40 males and 38 females) who had MIGS: 50 KDB, 13 iStent, 23 iStent inject, and 7 GATT. An overall reduction in the number of anti-glaucoma medications (p<0.001) was statistically significant. In the study, 36.6% of patients had a better social life, but 85.2% had no change in occupational life. Eventually, 86% were satisfied with the operation’s outcome, and 79% confirmed that the overall quality of life improved after the procedure.

Conclusion

Evaluating QOL is a crucial component of glaucoma treatment. More research is needed on MIGS and their relationship to QOL. In the future, MIGS may provide the desired outcomes in controlling glaucoma and improving the QOL.

Comparison of a second-generation trabecular bypass (iStent inject) to ab interno trabeculectomy (Trabectome) by exact matching

Purpose

To achieve a highly balanced comparison of trabecular bypass stenting (IS2, iStent inject) with ab interno trabeculectomy (T, Trabectome) by exact matching.

Methods

Fifty-three IS2 eyes were matched to 3446 T eyes. Patients were matched using exact matching by baseline intraocular pressure (IOP), the number of glaucoma medications, and glaucoma type, and using nearest neighbor matching by age. Individuals without a close match were excluded. All surgeries were combined with phacoemulsification.

Results

A total of 78 eyes (39 in each group) could be matched as exact pairs with a baseline IOP of 18.3 ± 5.1 mmHg and glaucoma medications of 2.7 ± 1.2 in each. IOP in IS2 was reduced to 14.6 ± 4.2 mmHg at 3 months and in T to a minimum of 13.1 ± 3.2 mmHg at 1 month. In IS2, IOP began to rise again at 6 months, eventually exceeding baseline. At 24 months, IOP in IS2 was 18.8 ± 9.0 mmHg and in T 14.2 ± 3.5 mmHg. IS2 had a higher average IOP than T at all postoperative visits (p < 0.05 at 1, 12, 18 months). Glaucoma medications decreased to 2.0 ± 1.5 in IS2 and to 1.5 ± 1.4 in T.

Conclusion

T resulted in a larger and sustained IOP reduction compared with IS2 where a rebound occurred after 6 months to slightly above preoperative values.

Predictors of Intraocular Pressure Lowering after Phacoemulsification and iStent Implantation

PURPOSE

To explore the demographic and clinical variables associated with intraocular pressure (IOP) lowering after cataract extraction (CE) alone or CE in combination with the iStent (Glaukos Corporation) placement (CE+IS).

DESIGN

Retrospective data extraction and survival analysis of consecutive patients identified over a 2-year period.

PARTICIPANTS

Patients with mild to moderate glaucoma who underwent CE (48 eyes of 32 patients) or CE+IS (61 eyes of 37 patients) were analyzed.

METHODS

Inability to reduce the number of medications or the IOP by at least 20% compared with baseline on 2 consecutive visits was considered surgical failure. Using Cox proportional hazards models, survival analysis was performed, and demographic and clinical variables were evaluated as risk factors.

MAIN OUTCOME MEASURES

Time to failure after surgical procedure.

RESULTS

CE+IS had lower odds of failure than CE alone (hazard ratio [HR], 2.01; P = 0.047). In White patients, CE+IS showed greater odds of success compared with CE alone (HR, 2.86; P = 0.007). For non-White patients, no difference was found in the outcomes for the 2 procedures (HR, 0.59; P = 0.48). In the multivariate analysis, non-White race (HR, 8.75; P = 0.0002) and longer axial length (HR, 1.61; P = 0.03) were associated with greater hazard of failure after CE+IS. In the CE group, greater odds of failure were associated with steeper corneal curvature (HR, 1.74; P = 0.008), shallower anterior chamber (HR, 0.22; P = 0.008), and longer axial length (HR, 1.58; P = 0.01).

CONCLUSIONS

Addition of the iStent to CE improved the duration of IOP lowering in White patients, but not in non-White patients. Associations between IOP lowering after CE and biometric parameters may allow for leveraging these clinical parameters for better case selection for these procedures.

Effectiveness of iStent Trabecular Microbypass System Combined with Phacoemulsification versus Phacoemulsification Alone in Patients with Glaucoma and Cataract Depending on the Initial Intraocular Pressure

INTRODUCTION

To assess the effect of iStent trabecular microbypass implantation combined with phacoemulsification on intraocular pressure (IOP) and glaucoma medications and to compare this to outcomes of phacoemulsification alone in patients with mild to moderate primary open-angle glaucoma (POAG) depending on initial IOP.

MATERIALS AND METHODS

Eighty subjects with cataract and POAG were randomized 1:1 into either iStent implantation and cataract surgery (iStent group) (n = 44) or cataract surgery alone (control group) (n = 36). Groups were divided according to initial IOP (after washout period) into IOP <26 mm Hg and IOP ≥26 mm Hg. Patients were assessed preoperatively and at postoperative day 1, week 1, and months 1, 3, 6, 12, and 24. Outcome measures included best-corrected visual acuity, IOP, and glaucoma medications.

RESULTS

Postoperatively at 24 months, mean IOP decreased from 20.93 ± 1.28 to 17.79 ± 2.50 mm Hg in the IOP subgroup <26 mm Hg and from 26.00 ± 0.00 to 19.86 ± 2.19 in the subgroup ≥26 mm Hg in the control group. In the iStent group <26 mm Hg, IOP decreased from 22.04 ± 1.64 to 15.57 ± 2.13 mm Hg and from 26.6 ± 1.09 to 17.06 ± 2.43 mm Hg in the iStent group ≥26 mm Hg.

CONCLUSION

In patients with open-angle glaucoma and cataract, iStent implantation combined with cataract surgery reduced IOP significantly through 2 years, with greater reductions achieved versus phacoemulsification alone. In patients with baseline IOP <26 mm Hg, surgery reduced IOP and medication use significantly declined through 2 years, with greater reductions achieved versus patients with baseline IOP ≥26 mm Hg. The study was registered at ClinicalTrials.gov under the number NCT03807869.

Influence of oral anticoagulation on success rates and risk of bleeding events after iStent inject implantation combined with phacoemulsification

Purpose

We conducted a retrospective study to evaluate the intraocular pressure (IOP) lowering effect, the success rates, and the risk of bleeding events of patients receiving an iStent inject combined with phacoemulsification under anticoagulation therapy compared with a matched control group.

Methods

In this retrospective study, sixty-four eyes underwent an iStent inject implantation combined with phacoemulsification at two centers. Thirty-two eyes received surgery while under anticoagulation therapy, and another thirty-two eyes served as a control group matched for visual acuity, IOP, and medication score. Success was defined as criteria A and B (IOP < 18/21 mmHg, > 20% IOP reduction, no resurgery) and criteria C (IOP ≤ 15 mmHg, IOP reduction ≥ 40%, no resurgery). The clinical goal of the study was to determine the difference between the study and control groups with respect to IOP, medication score, and the frequency of intraoperative and postoperative bleeding events.

Results

After a mean follow-up time of 1 year, the IOP lowered 28% from 20.1 ± 4.8 to 14.5 ± 3.7 mmHg in the group of 64 eyes. The medication score lowered 38% from 2.1 ± 1.1 to 1.3 ± 1.2. The two groups with and without anticoagulant agents did not significantly differ in postoperative IOP, medication score, success rates, or number of bleeding events.

Conclusion

We conclude that in cataract surgery combined with the iStent inject a discontinuation of anticoagulant agents might not be necessary. It might be a good option in glaucoma surgery when anticoagulation treatment should not be interrupted and the target pressure is not very low.

Endophthalmitis following combined cataract extraction and placement of an iStent trabecular bypass device

Purpose

To report a case of post-operative endophthalmitis following combined cataract extraction and minimally invasive glaucoma surgery with placement of the iStent drainage device.

Observation

An 87-year-old woman with a nuclear sclerotic cataract and primary open angle glaucoma underwent elective phacoemulsification cataract extraction with iStent placement. Surgery was complicated only by the inability to properly place the second iStent despite several attempts. At 4 days post-operatively she was diagnosed with endophthalmitis. Despite the prompt intravitreal injections of broad spectrum antibiotics, she lost all perception of light. Cultures of anterior chamber aspirates failed to identify a causative organism.

Conclusion and importance

In what we believe to be the first report of endophthalmitis associated with placement of the iStent, complete loss of vision occurred. Surgeons need to be aware that iStent placement may be complicated by severe endophthalmitis.

Five-Year Outcomes Prospective Study of Two First-Generation Trabecular Micro-Bypass Stents (iStent®) in Open-Angle Glaucoma

PURPOSE

To assess 5-year effectiveness and safety of 2 iStent® trabecular micro-bypass stents in eyes with open-angle glaucoma (OAG) not controlled on 1 medication.

MATERIALS AND METHODS

This prospective, interventional, single-arm, multi-surgeon study (NCT #1252862, clinicaltrials.gov) enrolled eyes with OAG, preoperative intraocular pressure (IOP) of 18-30 mmHg on 1 ocular hypotensive medication, and 22-38 mmHg after medication washout. Eyes underwent standalone implantation of 2 iStent devices and were followed through 60 months postoperatively. Efficacy was quantified by mean diurnal IOP and medication usage. Efficacy endpoints included the proportion of eyes with ≥20% IOP reduction versus baseline unmedicated IOP (primary efficacy), and the proportion of eyes with IOP ≤18 mmHg (secondary efficacy) without medication or secondary glaucoma surgery. Safety parameters included visual acuity, cup-to-disc ratio, visual field, and complications and adverse events.

RESULTS

Preoperative mean IOP on 1 medication was 20.6 ± 2.0 mmHg and post-washout unmedicated IOP was 24.1 ± 1.4 mmHg (n = 39). At 5 years postoperative, medication-free mean diurnal IOP reduced to 14.5 ± 2.2 mmHg, constituting a 40% decrease versus preoperative washed-out IOP (p < .0001). In addition, this 5-year medication-free IOP constituted a 30% decrease versus preoperative IOP on 1 medication (p < .0001). At Month 60, 89.7% (26/29) of eyes achieved the primary efficacy endpoint of ≥20% IOP reduction versus baseline unmedicated IOP, and 86.2% (25/29) of eyes achieved the secondary efficacy endpoint of IOP ≤18 mmHg, without medication or secondary glaucoma surgery. Throughout follow-up, 89.7-91.3% of eyes were on no medications. Favorable safety included no secondary glaucoma surgeries, minimal adverse events, and stable visual acuity, cup-to-disc ratio, and visual fields through 5 years postoperative.

CONCLUSIONS

This prospective interventional study demonstrates persistent 5-year reductions in IOP and freedom from medications, together with favorable safety, following implantation of 2 first-generation trabecular micro-bypass stents in eyes with OAG on 1 preoperative medication.

Performances of glaucoma operations with Kahook Dual Blade or iStent combined with phacoemulsification in Japanese open angle glaucoma patients

AIM

To compare surgical outcomes of phacoemulsification combined with glaucoma surgical techniques performed with either Kahook Dual Blade (KDB) or iStent for Japanese patients with either primary open angle glaucoma or exfoliation glaucoma.

METHODS

We retrospectively evaluated the surgical outcomes of 129 eyes of 84 Japanese patients with glaucoma who underwent KDB or 44 eyes of 34 patients who underwent phacoemulsification with iStent procedures combined with cataract surgery. The primary outcome was surgical success or failure [with surgical failure being indicated by <20% reduction from preoperative intraocular pressure (IOP) or IOP>18 mm Hg as criterion A; IOP>14 mm Hg as criterion B on two consecutive study visits; or reoperation requirement]. In addition, we assessed the number of postoperative glaucoma medications and the resulting complications.

RESULTS

The probability of success was significantly higher in the KDB group than in the iStent group for criterion A (60.2% vs 46.4%, P=0.019). In the KDB group, the mean preoperative IOP of 19.8±7.3 mm Hg decreased significantly to 13.0±3.1 mm Hg (P<0.01), and the mean number of glaucoma medications at 2.5±1.4 decreased significantly to 1.6±1.6 (P<0.01) 12mo postoperatively. In the iStent group, the mean preoperative IOP of 17.8±2.9 mm Hg significantly decreased to 14.3±2.3 mm Hg (P<0.01), and the mean number of glaucoma medications at 2.2±1.1 decreased significantly to 0.9±1.4 (P<0.01) 12mo postoperatively. The overall IOP reduction percentage was higher in the KDB group (26.2%) than in the iStent group (19.0%) 12mo postoperatively (P=0.03). Hyphema occurred significantly more frequently in the KDB group (16.3%) than in the iStent group (2.3%, P=0.017).

CONCLUSION

KDB and iStent procedures combined with cataract surgery both result in significant IOP and glaucoma medication reductions after the 12-month follow-up. The patients in the KDB group have a higher success rate for the target IOP of less than 18 mm Hg and a higher complication rate than those in the iStent group.

Real-world Case Series of iStent or iStent inject Trabecular Micro-Bypass Stents Combined with Cataract Surgery

INTRODUCTION

This real-world retrospective case series assessed 12-month effectiveness and safety following implantation of iStent® or iStent inject® trabecular micro-bypass with cataract surgery.

METHODS

Consecutive patients were implanted with either iStent (comprising 1 stent) or iStent inject (comprising 2 stents), together with cataract surgery. Most patients had primary open-angle glaucoma. Effectiveness outcomes through 12 months included intraocular pressure (IOP) and glaucoma medications. Proportional analyses were completed for eyes achieving IOP ≤ 18 mmHg, IOP ≤ 15 mmHg, or IOP reduction ≥ 20% from preoperative; and eyes on 0 medications or ≥ 2 medications. Safety outcomes included adverse events, secondary surgeries, visual acuity, and visual fields.

RESULTS

This analysis included 137 eyes (67 iStent, 70 iStent inject) with cataract and mild to moderate glaucoma or ocular hypertension. Over 73% of eyes in both groups had early disease, and ~ 22% had prior glaucoma surgery. At 12 months postoperatively, mean IOP decreased from 18.4 ± 4.2 mmHg to 14.2 ± 2.5 mmHg in iStent eyes (p < 0.0001), and from 20.4 ± 5.6 mmHg to 14.4 ± 2.1 mmHg in iStent inject eyes (p < 0.0001). The IOP reduction was significantly greater for iStent inject eyes than iStent eyes (6.0 mmHg versus 4.2 mmHg reduction, p = 0.034). Both groups had high proportions of patients achieving the 12-month IOP endpoints, although consistently greater proportions reached these endpoints after iStent inject than iStent: 95.7% versus 92.5% had IOP ≤ 18 mmHg, respectively; 74.3% versus 71.6% had IOP ≤ 15 mmHg, respectively; and 68.6% versus 62.7% had IOP reduction ≥ 20% from baseline, respectively. Mean medication burden at 12 months decreased from 1.8 ± 0.7 to 0.3 ± 0.5 medications in iStent eyes (84.0% reduction, p < 0.0001), and from 1.3 ± 0.9 to 0.1 ± 0.3 medications in iStent inject eyes (94.7% reduction, p < 0.0001). Significantly more iStent inject eyes were medication-free at 12 months than iStent eyes (92.9% versus 76.1% medication-free, respectively; p = 0.0068). Favorable safety included few adverse events, no secondary glaucoma surgeries, and stable visual acuity and visual fields in both groups.

CONCLUSION

Significant and safe IOP and medication reductions were achieved through 12 months after iStent or iStent inject implantation with cataract surgery. iStent inject eyes had greater absolute IOP reduction and more eyes medication-free versus iStent eyes.

FUNDING

Glaukos Corporation.

Comparison Of Surgical Outcomes Between Excisional Goniotomy Using The Kahook Dual Blade And iStent Trabecular Micro-Bypass Stent In Combination With Phacoemulsification

PURPOSE

To compare 6-month surgical outcomes of patients who underwent phacoemulsification (Phaco) combined with iStent implantation (iStent) versus excisional goniotomy using Kahook Dual Blade (KDB).

METHODS

Retrospective comparative case series of 58 iStent-Phaco eyes and 44 KDB-Phaco eyes operated upon by a single surgeon between 2016 and 2018. Preoperative, intraoperative, and postoperative intraocular pressure (IOP) and IOP-lowering medication data were collected. The primary outcome was the proportion of eyes using ≥1 fewer IOP-lowering medication at Month 6 while maintaining IOP ≤ 18 mmHg.

RESULTS

Baseline IOP was 17.2 (standard error 0.7) in the KDB-Phaco group using a mean of 1.9 (0.2) medications; at Month 6, mean IOP was 14.8 mmHg P=0.002) on 1.0 (0.2) medications (P<0.002). Baseline IOP was 16.7 (0.4) in the iStent-Phaco group using a mean of 1.4 (0.1) medications; at Month 6, mean IOP was 14.2 mmHg (P<0.002) on 1.4 (0.1) medications P=0.374). Changes in IOP and medications were not significantly different between groups (P>0.05). Significantly more KDB-Phaco eyes than iStent-Phaco eyes (43.2% vs 17.2%, P=0.004) were using ≥1 fewer medications while maintaining IOP ≤18 mmHg at Month 6. Adverse events were uncommon and similar in nature and frequency between groups with the exception that more KDB-Phaco eyes than iStent-Phaco eyes (8 [18.2%] versus 1 [1.7%]) experienced an IOP elevation presumed to be related to steroid use.

CONCLUSION

KDB-Phaco and iStent-Phaco provided comparable IOP and medication reductions. The proportion of eyes able to discontinue 1 or more medications while maintaining IOP ≤ 18 mmHg was significantly greater in eyes undergoing KDB-Phaco.

One-Year Comparative Evaluation of iStent or iStent inject Implantation Combined with Cataract Surgery in a Single Center

INTRODUCTION

This retrospective consecutive case series assessed 12-month effectiveness and safety of iStent® or iStent inject® trabecular micro-bypass implants with cataract surgery in patients with open-angle glaucoma (OAG) in a real-world clinical setting.

METHODS

Effectiveness outcomes consisted of intraocular pressure (IOP) reduction; glaucoma medication reduction; proportions of eyes achieving IOP < 18, < 15, or < 12 mmHg; and proportional analysis of medication usage. Safety outcomes included adverse events, secondary surgeries, and best-corrected visual acuity (BCVA).

RESULTS

This evaluation included 58 eyes with OAG (35 iStent, 23 iStent inject), with 96.6% of eyes having mild or moderate glaucoma. Diagnoses included primary open-angle glaucoma (the majority; 72.4%), pseudoexfoliative glaucoma, and pigmentary glaucoma. Baseline mean IOP and medications were statistically comparable between groups: 16.1 ± 3.6 mmHg on a mean of 1.8 ± 0.8 medications in the iStent group, and 16.2 ± 3.1 mmHg on a mean of 1.7 ± 0.8 medications in the iStent inject group. Twelve months after stent-cataract surgery, mean IOP was significantly lower in the iStent inject group than in the iStent group (13.1 mmHg vs. 15.4 mmHg, respectively; p < 0.001), and the percent reduction in IOP from baseline was significantly greater in iStent inject eyes than in iStent eyes (19.1% vs. 4.3% reduction, respectively; p < 0.001). At 12 months postoperative, significantly greater proportions of iStent inject eyes than iStent eyes achieved IOP < 18 mmHg (100% vs. 80.0% of eyes, respectively; p = 0.035), IOP < 15 mmHg (73.9% vs. 34.3% of eyes, respectively; p = 0.003), and IOP < 12 mmHg (26.1% vs. 0% of eyes, respectively; p = 0.002). Meanwhile, both groups achieved significant medication reductions at 12 months vs. baseline (94.1% reduction in iStent inject eyes, p < 0.0001; and 72.2% reduction in iStent eyes, p < 0.0001), with the percent reduction being significantly greater in iStent inject eyes than in iStent eyes (p = 0.023). At 12 months, mean number of medications was significantly lower in iStent inject eyes than iStent eyes (0.1 vs. 0.5 medications, respectively; p = 0.021), and significantly more iStent inject eyes (95.7%) than iStent eyes (71.4%) were off medications entirely (p = 0.021). A similarly high safety profile was observed in both groups.

CONCLUSION

iStent or iStent inject implantation with cataract surgery resulted in substantial and safe reductions in IOP and medications through 12 months postoperative. Consistent with prior observations, greater efficacy was observed with iStent inject than with iStent.

FUNDING

The Rapid Service Fees were funded by Glaukos Corporation.

12-Month Retrospective Comparison of Kahook Dual Blade Excisional Goniotomy with Istent Trabecular Bypass Device Implantation in Glaucomatous Eyes at the Time of Cataract Surgery

PURPOSE

To compare the efficacy and safety of combined cataract extraction and either excisional goniotomy performed with the Kahook Dual Blade (KDB; phaco-KDB group) or single iStent trabecular bypass implantation (phaco-iStent group) in eyes with mild to moderate glaucoma and visually significant cataract.

METHODS

This was a retrospective analysis of 315 eyes from 230 adults with mild or moderate glaucoma treated with one or more intraocular pressure (IOP)-lowering medications (190 eyes of 134 subjects in the phaco-KDB group and 125 eyes of 96 subjects in the phaco-iStent group) that required no subsequent surgical intervention for IOP control through 12 months of follow-up. Data included best-corrected visual acuity (BCVA), IOP, and IOP-lowering medications, collected preoperatively and at 1 week and 1, 3, 6, and 12 months postoperatively as well as intraoperative and postoperative adverse events. The primary efficacy outcomes were the proportion of subjects in each group achieving ≥ 20% IOP reduction and ≥ 1 medication reduction at month 12. Subgroup analysis by baseline IOP (≤ 18 mmHg vs. > 18 mmHg) was also performed.

RESULTS

Mean (standard error) baseline IOP was 18.2 (0.3) mmHg in the phaco-KDB group and 16.7 (0.3) mmHg in the phaco-iStent group (p = 0.001). Statistically significant mean IOP and mean IOP medication reductions from baseline were achieved at all time points in both groups. Mean IOP reductions were significantly greater in the phaco-KDB group than in the phaco-iStent group at all time points including month 12 [- 5.0 (0.3) mmHg vs. - 2.3 (0.4) mmHg, p < 0.001], while mean medication reductions were similar between groups at all time points except week 1, when greater mean medication reduction was seen in the phaco-iStent group (- 1.23 vs. - 0.60 medications, p < 0.001). At month 12, IOP reductions ≥ 20% were achieved by 64.2% and 41.6% (p < 0.001) in the phaco-KDB and phaco-iStent groups, respectively, and IOP medication reductions of ≥ 1 medication were achieved by 80.4% and 77.4% (p = 0.522), respectively. Intraocular pressure subgroup analysis revealed significant reductions in IOP-lowering medications without compromise of IOP control in lower IOP subgroups and significant reductions in both IOP and IOP-lowering medications in the higher IOP subgroups. The most common adverse events were transient IOP elevations and transient anterior chamber inflammation, which occurred with similar frequency in both groups and resolved spontaneously.

CONCLUSION

Goniotomy with the KDB lowered IOP significantly more than iStent implantation, with few adverse events in both groups. In eyes with mild to moderate glaucoma undergoing combined cataract extraction and glaucoma surgery, goniotomy with the KDB can safely deliver statistically significant and clinically meaningful reductions in both IOP and IOP medication burden through 12 months of follow-up.

FUNDING

New World Medical, Inc., provided funding for the study, medical writing assistance, Rapid Service Fees, and the open access fee.

Cost-effectiveness analysis of standalone trabecular micro-bypass stents in patients with mild-to-moderate open-angle glaucoma in Canada

OBJECTIVES

To estimate the cost-utility of two trabecular micro-bypass stents (TBS) implantation vs standard of care (SOC) in patients with mild-to-moderate open-angle glaucoma (OAG) in the Canadian healthcare setting.

METHODS

The deterioration in visual field (VF) defect over a 15-year time horizon was tracked using a Markov model with Hodapp-Parrish-Anderson stages of glaucoma (mild, moderate, advanced, severe/blind) and death as health states. Meta-analyses of randomized clinical trials were conducted to estimate the pooled reduction in intraocular pressure (IOP) and medication use due to TBS and SOC. The rate of decline in VF loss was adjusted by the extent of IOP reduction to estimate transition probabilities. Healthcare resource utilization, unit costs (2017 CAD), and progression-related utility scores were obtained by literature review, and medication costs with wastage were obtained from IMS Brogan PharmaStat. The impact of parameter and methodological uncertainty on costs and quality-adjusted life years (QALYs) was examined using probabilistic and 1-way sensitivity analyses.

RESULTS

The meta-analysis showed an additional reduction of 1.13 medications/patient and an additional decrease in IOP of -1.10 mmHg at 36 months favoring TBS. TBS strongly dominated medication alone, due to higher improvement in quality-of-life (0.068 QALYs), fewer blind eyes (-0.0031), and a decrease in total healthcare costs of C$2,908.3 per patient over the time horizon (C$9,394.1 TBS vs C$12,302.4 medication alone). Sensitivity analyses showed that results were robust to the uncertainties in model inputs and assumptions. Time-to-dominance was 44 months (3.7 years).

CONCLUSIONS

The TBS procedure was cost-effective over SOC in a 15-year time horizon, with quality-of-life gains.

Intermediate Results of iStent or iStent inject Implantation Combined with Cataract Surgery in a Real-World Setting: A Longitudinal Retrospective Study

INTRODUCTION

In this real-world, retrospective, comparative study we evaluated 6-month performance and safety in consecutive eyes following implantation of the iStent® or iStent inject® trabecular micro-bypass device with concomitant cataract surgery.

METHODS

Performance outcomes included intraocular pressure (IOP) reduction; glaucoma medication reduction; proportions of eyes achieving an IOP of < 18, < 16, < 14, or < 12 mmHg; and proportions of eyes on 0, 1, 2, or ≥ 3 medications. Safety outcomes included adverse events, secondary surgeries, and best-corrected visual acuity (BCVA).

RESULTS

A total of 73 eyes with open-angle glaucoma and cataract were included in the study; of these, 38 eyes were implanted with the iStent device and 35 were implanted with the iStent inject device. The two groups of patients had similar baseline characteristics, with the exception of mean age and medication burden (both higher in patients receiving the iStent inject device); over 90% of eyes in both groups had early glaucoma. At 6 months after surgery, mean IOP had fallen from 16.5 ± 3.9 to 13.9 ± 2.3 mmHg in eyes with the iStent implant (p < 0.001), and from 17.3 ± 3.0 to 12.7 ± 1.8 mmHg in those with the iStent inject implant (p < 0.001). This reduction was significantly greater in the iStent inject eyes than in the iStent eyes (26.6 vs. 15.8%) (p = 0.005). Significantly more eyes receiving the iStent inject device compared to the iStent device achieved an IOP of < 18 mmHg at 6 months post surgery (100 vs. 86.8%) (p = 0.033). Average medication usage was reduced from 1.8 to 0.4 medications in iStent eyes (p < 0.001) and from 2.3 to 0.4 medications in iStent inject eyes (p < 0.001). Over 70% of eyes in both groups became medication-free by 6 months post implantation. Adverse events in iStent eyes were mild and resulted in no sequelae; two iStent eyes underwent non-penetrating deep sclerectomy during follow-up. No complications or secondary surgeries were noted in iStent inject eyes. All eyes in both groups maintained or showed improved BCVA versus baseline.

CONCLUSION

Significant and safe IOP and medication reductions were observed after iStent or iStent inject implantation with concomitant cataract surgery. Trends toward greater effectiveness and fewer adverse events were observed with the iStent inject device compared with the iStent device.

FUNDING

Article processing charges were provided by Glaukos Corporation.

A cost minimisation analysis comparing iStent accompanying cataract surgery and selective laser trabeculoplasty versus topical glaucoma medications in a public healthcare setting in New Zealand

PURPOSE

To produce an economic comparison of the iStent ab interno trabecular microbypass implant accompanying cataract surgery and selective laser trabeculoplasty (SLT) as first-line treatment versus topical medications for open-angle glaucoma in New Zealand in 2016.

METHODS

The current annual costs of 19 available fully subsidised topical glaucoma medications by Pharmaceutical Management Agency (Pharmac) in 2016 were identified. Adjustments for pharmacist prescribing charges and previously described wastage levels were applied. The costs to perform iStent implantation and the cost to perform SLT were obtained from the local distributors, with the latter taking into account staff and consumable cost. Procedure costs divided by eye drops' cost produced a break-even level in equivalent years of eye drops use.

RESULTS

The range of annual eye drop cost was NZD$42.25 to NZD$485.11, with an average of NZD$144.81. Comparison of annual eye drop cost with iStent cost revealed 3 of 19 (15.8%) drops breaking even within 5 years, 9 of 19 (47.3%) within 10 years, and 12 of 19 (63.2%) within 15 years. The cost of bilateral SLT performed by a consultant was NZD$102.30 (breaking even in 0.71 years). The equivalent cost for a registrar was NZD$97.59 (breaking even in 0.67 years).

CONCLUSION

Economically, the iStent would appear to be a reasonably cost-effective treatment for glaucoma patients undergoing cataract surgery in a public healthcare setting in New Zealand, particularly for those using more expensive topical glaucoma medications, whilst SLT appears to be a worthwhile consideration as a first-line treatment for glaucoma in New Zealand.

Systematic Literature Review of Clinical and Economic Outcomes of Micro-Invasive Glaucoma Surgery (MIGS) in Primary Open-Angle Glaucoma

INTRODUCTION

Primary open-angle glaucoma is estimated to affect 3% of the population aged 40-80 years. Trabeculectomy is considered the gold standard in surgical management of glaucoma; however, it is a technically complex procedure that may result in a range of adverse outcomes. Device-augmented, minimally invasive procedures (micro-invasive glaucoma surgeries, MIGS) have been developed aiming for safer and less invasive intraocular pressure (IOP) reduction compared with traditional surgery.

METHODS

This paper presents results from a systematic literature review conducted in accordance with National Institute for Health and Care Excellence requirements for the Medical Technology Evaluation Programme via multiple databases from 2005 to 2016. For clinical outcomes, randomized clinical trials (RCTs) comparing MIGS with trabeculectomy or other therapies, observational studies, and other non-RCTs were included. Clinical outcomes reviewed were the change from baseline in mean IOP levels and change in topical glaucoma medication. Safety was assessed by reported harm and adverse events. For economic evidence, trials on cost-effectiveness, cost-utility, cost-benefit, cost-consequences, cost-minimization, cost of illness, and specific procedure costs were included. Risk of bias was assessed for clinical studies using the Cochrane Risk of Bias tool.

RESULTS

A total of nine RCTs (seven iStents^®, one Hydrus^®, and one CyPass^®), seven non-RCTs (three iStent^®, three CyPass^®, and one Hydrus^®), and 23 economic studies were analyzed. While various forms of trabeculectomy can achieve postoperative IOP of between 11.0 and 13.0 mmHg, MIGS devices described in this review were typically associated with higher postoperative IOP levels. In addition, MIGS devices may result in increased hypotony rates or bleb needling in subconjunctival placed devices, requiring additional medical resources to manage. There is limited available evidence on the cost-effectiveness of MIGS and therefore it remains unclear whether the cost of using MIGS is outweighed by cost savings through decreased medication and need for further interventions.

CONCLUSION

Larger randomized trials and real-world observational studies are needed for MIGS devices to better assess clinical and economic effectiveness. Given the shortage of published data and increasing use of such procedures, living systematic reviews may help to provide ongoing and timely evidence-based direction for clinicians and decision makers. This review highlights the current unmet need for treatments that are easy to implement and reduce long-term IOP levels without increasing postoperative aftercare and cost.

FUNDING

Santen GmbH, Germany.

Prospective Evaluation of Two iStent® Trabecular Stents, One iStent Supra® Suprachoroidal Stent, and Postoperative Prostaglandin in Refractory Glaucoma: 4-year Outcomes

Introduction

This study evaluates long-term outcomes of two trabecular micro-bypass stents, one suprachoroidal stent, and postoperative prostaglandin in eyes with refractory open angle glaucoma (OAG).

Methods

Prospective ongoing 5-year study of 80 eligible subjects (70 with 4-year follow-up) with OAG and IOP ≥ 18 mmHg after prior trabeculectomy and while taking 1–3 glaucoma medications. Subjects received two iStent^® trabecular micro-bypass stents, one iStent Supra^® suprachoroidal stent, and postoperative travoprost. Postoperative IOP was measured with medication and annually following medication washouts. Performance was measured by the proportion of eyes with ≥ 20% IOP reduction on one medication (the protocol-specified prostaglandin) versus preoperative medicated IOP (primary outcome); and the proportion of eyes with postoperative IOP ≤ 15 and ≤ 18 mmHg on one medication (secondary outcome). Additional clinical and safety data included medications, visual field, pachymetry, gonioscopy, adverse events, visual acuity, and slit-lamp and fundus examinations.

Results

Preoperatively, mean medicated IOP was 22.0 ± 3.1 mmHg on 1.2 ± 0.4 medications, and mean unmedicated IOP was 26.4 ± 2.4 mmHg. Postoperatively, among eyes without later cataract surgery, mean medicated IOP at all visits through 48 months was ≤ 13.7 mmHg (≥ 37% reduction), and annual unmedicated IOP was ≤ 18.4 mmHg (reductions of ≥ 30% vs. preoperative unmedicated IOP and ≥ 16% vs. preoperative medicated IOP). At all postoperative visits among eyes without additional surgery or medication, ≥ 91% of eyes had ≥ 20% IOP reduction on one medication versus preoperative medicated IOP. At month 48, 97 and 98% of eyes achieved IOP ≤ 15 and ≤ 18 mmHg, respectively, on one medication. Six eyes required additional medication, no eyes required additional glaucoma surgery, and safety measurements were favorable throughout follow-up.

Conclusion

IOP control was achieved safely with two trabecular micro-bypass stents, one suprachoroidal stent, and postoperative prostaglandin. This microinvasive, ab interno approach introduces a possible new treatment option for refractory disease.

Trial Registration

NCT01456390.

Funding

Glaukos Corporation.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0666-4) contains supplementary material, which is available to authorized users.

Long-term titrated IOP control with one, two, or three trabecular micro-bypass stents in open-angle glaucoma subjects on topical hypotensive medication: 42-month outcomes

Purpose

Evaluate long-term outcomes after one, two, or three trabecular micro-bypass stents implanted in a standalone procedure in eyes with open-angle glaucoma taking ocular hypotensive medication.

Patients and methods

Prospective randomized ongoing study of 119 subjects (109 with 42-month follow-up) with open-angle glaucoma, preoperative intraocular pressure (IOP) 18-30 mmHg on one to three glaucoma medications, and unmedicated (post-washout) IOP 22-38 mmHg. Subjects were randomized to receive one (n=38), two (n=41), or three (n=40) iStent trabecular micro-bypass stents in a standalone procedure. Postoperatively, IOP was measured with medication and annually following washout. Data included IOP, medications, gonioscopy, pachymetry, visual field, visual acuity, adverse events, and slit-lamp and fundus examinations.

Results

Preoperative mean medicated IOP was 19.8±1.3 mmHg on 1.71 medications in one-stent eyes, 20.1±1.6 mmHg on 1.76 medications in two-stent eyes, and 20.4±1.8 mmHg on 1.53 medications in three-stent eyes. Post-washout IOP prior to stent implantation was 25.0±1.2, 25.0±1.7, and 25.1±1.9 mmHg in the three groups, respectively. Postoperatively, Month 42 medicated IOP was 15.0±2.8, 15.7±1.0 and 14.8±1.3 mmHg in the three groups, and post-washout IOP (Months 36-37) was 17.4±0.9, 15.8±1.1 and 14.2±1.5 mmHg, respectively. IOP reduction ≥20% without medication was achieved in 89%, 90%, and 92% of one-, two-, and three-stent eyes, respectively, at Month 12; and in 61%, 91%, and 91% of eyes, respectively, at Month 42. The need for additional medication remained consistent at Months 12 and 42 in multi-stent eyes (four two-stent eyes and three three-stent eyes at both time points), whereas it increased in single-stent eyes (four eyes at Month 12 versus 18 eyes at Month 42). Safety parameters were favorable in all groups.

Conclusion

The standalone implantation of either single or multiple iStent^® device(s) produced safe, clinically meaningful IOP and medication reductions through 42 months postoperatively, with incrementally greater and more sustained reductions in multi-stent eyes.

Micro-invasive glaucoma surgery (MIGS): a review of surgical procedures using stents

Over the last decade several novel surgical treatment options and devices for glaucoma have been developed. All these developments aim to cause as little trauma as possible to the eye, to safely, effectively, and sustainably reduce intraocular pressure (IOP), to produce reproducible results, and to be easy to adopt. The term “micro-invasive glaucoma surgery (MIGS)” was used for summarizing all these procedures. Currently MIGS is gaining more and more interest and popularity. The possible reduction of the number of glaucoma medications, the ab interno approach without damaging the conjunctival tissue, and the probably safer procedures compared to incisional surgical methods may explain the increased interest in MIGS. The use of glaucoma drainage implants for lowering IOP in difficult-to-treat patients has been established for a long time, however, a variety of new glaucoma micro-stents are being manufactured by using various materials and are available to increase aqueous outflow via different pathways. This review summarizes published results of randomized clinical studies and extensive case report series on these devices, including Schlemm’s canal stents (iStent^®, iStent^® inject, Hydrus), suprachoroidal stents (CyPass^®, iStent^® Supra), and subconjunctival stents (XEN). The article summarizes the findings of published material on efficacy and safety for each of these approaches.

An Update on Implants for Minimally Invasive Glaucoma Surgery (MIGS)

For several years, the gold standard for surgical treatment of glaucoma has been trabeculectomy. Although very successful at reducing intraocular pressure (IOP), there are several potential complications of trabeculectomy, including sight-threatening ones. This has stimulated much research aimed at the development of new and effective procedures to lower IOP with an enhanced safety profile. Minimally invasive glaucoma surgery (MIGS) procedures prioritise patient safety but also demonstrate efficacy in reducing IOP. We performed an online search of peer-reviewed literature using PubMed, entering keywords relevant to this clinical discipline. In summary, there is a lack of long-term safety and efficacy data, a lack of comparative data and a lack of data on standalone (i.e. without simultaneous cataract surgery) procedures. Most implants are not yet FDA approved. Although not exhaustive, since it does not discuss MIGS procedures that are not implants, this article summarises the range of different MIGS implants that are available to the ophthalmic surgeon.

Cost-comparison of two trabecular micro-bypass stents versus selective laser trabeculoplasty or medications only for intraocular pressure control for patients with open-angle glaucoma

AIM

Patients with open-angle glaucoma (OAG) whose intraocular pressure is not adequately controlled by one medication have several treatment options in the US. This analysis evaluated direct costs of unilateral eye treatment with two trabecular micro-bypass stents (two iStents) compared to selective laser trabeculoplasty (SLT) or medications only.

MATERIALS AND METHODS

A population-based, annual state-transition, probabilistic, cost-of-care model was used to assess OAG-related costs over 5 years. Patients were modeled to initiate treatment in year zero with two iStents, SLT, or medications only. In years 1-5, patients could remain on initial treatment or move to another treatment option(s), or filtration surgery. Treatment strategy change probabilities were identified by a clinician panel. Direct costs were included for drugs, procedures, and complications.

RESULTS

The projected average cumulative cost at 5 years was lower in the two-stent treatment arm ($4,420) compared to the SLT arm ($4,730) or medications-only arm ($6,217). Initial year-zero costs were higher with two iStents ($2,810) than with SLT ($842) or medications only ($996). Average marginal annual costs in years 1-5 were $322 for two iStents, $777 for SLT, and $1,044 for medications only. The cumulative cost differences between two iStents vs SLT or medications only decreased over time, with breakeven by 5 or 3 years post-initiation, respectively. By year 5, cumulative savings with two iStents over SLT or medications only was $309 or $1,797, respectively.

LIMITATIONS

This analysis relies on clinical expert panel opinion and would benefit from real-world evidence on use of multiple procedures and treatment switching after two-stent treatment, SLT, or polypharmaceutical initial approaches.

CONCLUSIONS

Despite higher costs in year zero, annual costs thereafter were lowest in the two-stent treatment arm. Two-stent treatment may reduce OAG-related health resource use, leading to direct savings, especially over medications only or at longer time horizons.

Implantation of trabecular micro-bypass stent using a novel "landing strip" technique

AIM

To describe a novel technique of creating a landing strip within the trabecular meshwork to guide trabecular micro-bypass stent (iStent) implantation in patients who underwent phacoemulsification.

METHODS

Thirty-four eyes from 30 patients who underwent iStent implantation after phacoemulsification from May 2014 to February 2015 were included in our retrospective study. All iStents were implanted via the "landing strip" technique. A 25-gauge microvitreoretinal blade was used to bisect the trabecular meshwork to less than 1 clock-hour, effectively creating a landing strip. The iStent applicator was pressed along the landing strip and then the stent was released into the trabecular meshwork.

RESULTS

Of the 34 eyes with iStent implantation, 27 (79.4%) eyes had primary open-angle glaucoma, 6 (17.6%) eyes had pseudoexfoliation glaucoma, and 1 (2.9%) eye had ocular hypertension. At 6-month follow-up (n=17), the mean number of hypotensive medications decreased from 2.2±1.2 at baseline to 0.8±1.3 (P=0.05) and mean intraocular pressure decreased from 19.7±4.1 mm Hg at baseline to 16.7±2.1 mm Hg (P=0.58). Two eyes (5.9%) required subsequent trabeculectomy.

CONCLUSION

The "landing strip" technique appears to be an effective way to assist with iStent implantation.

Is there a change in the quality of life comparing the micro-invasive glaucoma surgery (MIGS) and the filtration technique trabeculectomy in glaucoma patients?

PURPOSE

This study was conducted to assess the impact on the Quality of Life (QOL) of micro-invasive glaucoma surgery (MIGS: iStent, Trabectome) and a penetrating technique such as Trabeculectomy (TE).

METHODS

This study evaluated 88 eyes of 88 open angle glaucoma patients undergoing glaucoma surgery: 43 (mean age 72.8 ± 8.8y, female 59.5 %, male 40.5 %) Trabectome (NeoMedix, Inc., Tustin, CA, USA), 20 (mean age 68.6 ± 16.4y, female 60 %, male 40 %) iStent (Glaucos Corporation, Laguna Hills, CA, USA), and 25 TE patients (mean age 74.2 ± 9.1y female 58.3 %, male 41.7 %). The National Eye Institute-Visual Functioning Questionnaire (VFQ-25) survey was used to assess the QOL at 6 months post surgery. The following 12 QOL parameters were evaluated: general health, ocular pain, general vision, near and distance activities, mental health, social functioning, role difficulties, dependency, driving, color vision, and peripheral vision. Intraocular pressure (IOP), number of topical medications, and visual acuity (VA) were examined preoperatively, 1 day, 6 weeks, 3 months, and 6 months post surgery. Statistical data were calculated using SPSS (v20.0, SPSS, Inc.).

RESULTS

There was no significant difference between TE and MIGS in the quality of life 6 months postoperatively. IOP was significantly lower in TE compared to MIGS at 6 weeks and 3 months postoperatively (p = 0.046 and p = 0.046). Number of medications was significantly decreased in TE compared to MIGS (p < 0.001). A significant difference in VA between TE and MIGS could be assessed at day 1 post-op (p = 0.011).

CONCLUSION

In this study cohort, the QOL can be maintained by all three surgical techniques. Patients, however, need lower numbers of topical medication in TE, which would impact QOL even though it is not included in the NEI-VFQ-25. The decision of the most appropriate surgical technique should be made by including single QOL categories, IOP and glaucoma medication outcome.