360° ab-interno trabeculotomy in refractory primary open-angle glaucoma

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.

Ab Interno Canaloplasty and Trabeculotomy Outcomes for Mild, Moderate, and Advanced Open-Angle Glaucoma: A ROMEO Analysis

Purpose

To determine if there was an association between severity of glaucoma and intraocular pressure (IOP) and medication (med) outcomes for patients in the ROMEO (Retrospective, Observational, Multicenter Evaluation of OMNI) study.

Setting

Eleven ophthalmology practices in 8 US states.

Design

Post-hoc analysis of all eyes enrolled and treated with ab interno canaloplasty and trabeculotomy in the retrospective, multicenter ROMEO study.

Methods

Eyes were grouped according to visual field mean deviation (MD): mild (MD better than -6 dB), moderate (MD between -6 and -12 dB), advanced (-12 dB or worse). IOP and med outcomes at 12 months were compared across groups. Least squares regression was used to assess the relationship of MD with month 12 IOP. Outcomes for 1st and last MD deciles were compared as a sensitivity analysis.

Results

One hundred and twenty-seven eyes were available for analysis including 79 mild, 42 moderate, 6 advanced. Most eyes had a reduction in IOP at Month 12 (70%) with most at 18 mmHg or less. Percentage IOP reduction was similar across the groups (mild 16.9%, moderate 18.6%, advanced 18.0%) with mean month 12 IOP between 14 and 16 mmHg. Medications were also reduced in all three groups; -0.8 (mild, P < 0.001), -0.55 (moderate, P < 0.05), and -1.0 (advanced, P = 0.139, ns). Regression analysis revealed no relationship between month 12 IOP and MD. Med reductions were observed for all groups with a reduction of 1 or more medications seen in (%, 95% CI) 69%, 59-79 (mild), 50%, 35-65 (moderate), and 60%, 21-99 (advanced). Secondary interventions tended to have greater incidence with worse MD likely reflecting lower desired IOP targets.

Conclusion

Analysis of data from the ROMEO study suggests that similar meaningful IOP and med reductions can be expected across the range of disease severity studied.

Outcomes of 60-Degree Nasal Goniotomy for Open Angle Glaucoma

PRCIS

Sixty-degree nasal sectoral juxtacanalicular space goniotomy with the single-use Espaillat juxtacanalicular space slider device significantly reduced intraocular pressure and the number of required glaucoma hypotensive medications, with sustained reductions over 24 months.

PURPOSE

This study analyzed the safety and efficacy of the Espaillat juxtacanalicular space slider during minimally invasive 60-degree nasal sectoral goniotomy for mild-to-moderate open angle glaucoma (OAG).

PATIENTS AND METHODS

This prospective, observational case series performed at a private clinical practice and outpatient surgery center assessed the eyes of patients with mild-to-moderate OAG who underwent phacoemulsification cataract surgery with 60-degree nasal sectoral goniotomy using the Espaillat juxtacanalicular space slider. The same surgeon performed all procedures. Intraocular pressure, intraocular pressure-lowering drugs, and adverse effects were assessed over 24 months, and a regression analysis of intraocular pressure reduction was performed. Success was defined as (1) A reduction in the intraocular pressure of at least 20% for at least 12 months, compared with the baseline value, and (2) a decrease in the number of medications by at least one for at least 12 months.

RESULTS

Among 38 eyes, 27 (72%) had moderate glaucoma, and 11 (28%) had mild glaucoma. Postoperatively, intraocular pressure was decreased by 38% at 12 months (mean 13.7±1.7 mmHg), 35% at 18 months (mean 14.4±1.8 mmHg), and 31% at 24 months (mean 15.2±1.9 mmHg). In addition, the number of topical glaucoma medications used decreased from a mean of 1.6 to 0.4 ( P <0.001). The main adverse event was temporary focal corneal edema (29 patients; 76%).

CONCLUSIONS

Using the Espaillat juxtacanalicular space slider during invasive 60-degree nasal sectoral goniotomy for OAG yielded a significant and sustained reduction in intraocular pressure and reduced the need for glaucoma medications with minimal adverse events.

Minimally Invasive Glaucoma Surgery: A Review of the Literature

Minimally invasive glaucoma surgery (MIGS) has emerged as a novel approach in the glaucoma treatment spectrum, offering a range of diverse procedures and devices aimed at reducing intraocular pressure (IOP). MIGS can be broadly classified into several categories: those that enhance trabecular outflow (Trabectome, iStent, Hydrus Microstent, Kahook Dual Blade, high frequency deep sclerotomy, and gonioscopy-assisted transluminal trabeculotomy), those that augment suprachoroidal outflow (CyPass Microstent and iStent Supra), those that target Schlemm's canal (TRAB360 and the OMNI Surgical System, Streamline, and Ab Interno Canaloplasty), and conjunctival bleb-forming procedures (EX-PRESS Glaucoma Filtration Device, Xen Gel Stent and PreserFlo MicroShunt). MIGS is considered to have a shorter surgical time and fewer severe complications when compared to traditional glaucoma surgeries such as trabeculectomy and glaucoma drainage device implantation (Ahmed, Baerveldt, and Molteno valves). This literature review comprehensively examines the distinct MIGS devices and procedures, their underlying mechanisms, and clinical outcomes, emphasizing the importance of evaluating the efficacy and complications of each approach individually. As the field of MIGS continues to evolve, it is crucial to prioritize high-quality, long-term studies to better understand the safety and effectiveness of these innovative interventions in glaucoma management.

Ab-interno Trabeculotomy Procedures: A Review

Purpose

To discuss the safety and efficacy of various forms of ab-interno trabeculotomy procedures.

Methods

A comprehensive search in PubMed and Google Scholar was done using the keywords "glaucoma", "microinvasive glaucoma surgery", "complications", "goniotomy", and "trabeculotomy". Publications discussing ab-interno trabeculotomy procedures were selected; furthermore, the relevant references in these articles were gathered and the search was updated during the article preparation. Since gonioscopy-assisted transluminal trabeculotomy was first introduced in 2014, we had no time restriction.

Results

Ab-interno trabeculotomy procedures, as a type of minimally invasive glaucoma surgeries, facilitate the natural trabecular outflow and lower the intraocular pressure (IOP) while preserving the conjunctiva for possible future glaucoma surgeries. It can be done alone or in combination with cataract surgery and effectively lowers the IOP and the number of antiglaucoma medications in various forms of glaucoma.

Conclusion

By appropriate patient selection, ab-interno trabeculotomy could be selected as a safe and effective procedure in the management of various forms of glaucoma either as an isolated procedure or in combination with cataract extraction.

Gonioscopy-assisted transluminal trabeculotomy for open-angle glaucoma with failed incisional glaucoma surgery: two-year results

BACKGROUND

To evaluate the safety and efficacy of gonioscopy-assisted transluminal trabeculotomy (GATT) in treating patients with open-angle glaucoma (OAG) who had failed prior incisional glaucoma surgery.

METHODS

A consecutive case series of OAG patients aged ≥ 18 who underwent GATT with previous failed glaucoma incision surgery was retrospectively analyzed. Main outcome measures included intraocular pressure (IOP), the number of glaucoma medications, surgical success rate, and occurrence of complications. Success was defined as an IOP of ≤ 21 mmHg and a reduction of IOP by 20% or more from baseline with (qualified success) or without (complete success) glaucoma medications. For eyes with preoperative IOP of < 21 mmHg on 3 or 4 glaucoma medications, postoperative IOP of ≤ 18 mmHg without any glaucoma medications was also defined as complete success.

RESULTS

Forty-four eyes of 35 patients (21 with juvenile-onset open-angle glaucoma and 14 with adult-onset primary open-angle glaucoma) with a median age of 38 years were included in this study. The proportion of eyes with 1 prior incisional glaucoma surgery was 79.5%, and the others had 2 prior surgeries. IOP decreased from 27.4 ± 8.8 mm Hg on 3.6 ± 0.7 medications preoperatively to 15.3 ± 2.7 mm Hg on 0.5 ± 0.9 medications at the 24-month visit (P < 0.001). The mean IOP and the number of glaucoma medications at each follow-up visit were lower than the baseline (all P < 0.001). At 24 months postoperatively, 82.1% of the eyes had IOP ≤ 18 mmHg (versus 15.9% preoperatively, P < 0.001), 56.4% reached IOP ≤ 15 mmHg (versus 4.6% preoperatively, P < 0.001), and 15.4% achieved IOP ≤ 12 mmHg (compared to none preoperatively, P = 0.009). While 95.5% of eyes took 3 or more medications preoperatively, 66.7% did not take glaucoma medication 24 months after GATT. Thirty-four (77.3%) eyes achieved IOP reduction greater than 20% on fewer medications. The complete and qualified success rates were 60.9% and 84.1%, respectively. No vision-threatening complications occurred.

CONCLUSIONS

GATT was safe and effective in treating refractory OAG patients who failed prior incisional glaucoma surgery.

The case for standalone micro-invasive glaucoma surgery: rethinking the role of surgery in the glaucoma treatment paradigm

PURPOSE OF REVIEW

To highlight progress in glaucoma therapy challenging the traditional medication-first approach and present evidence supporting early standalone surgery in the era of micro-invasive glaucoma surgery (MIGS).

RECENT FINDINGS

Medical therapy is limited by well documented poor adherence that compromises the quality of intraocular pressure reduction. Results from modern clinical trials demonstrate advantages of selective laser trabeculoplasty and MIGS procedures in terms of both IOP control and progression risk.

SUMMARY

The MIGS options for pseudophakic or precataractous patients are limited by regulatory rules that require the performance of some procedures only at the time of cataract surgery. These include the iStent/iStent Inject and the Hydrus implants. Nonbleb-forming procedures currently available for standalone use in eyes with mild-moderate primary open-angle glaucoma include gonioscopy-assisted transluminal trabeculotomy (which lowers IOP by 28-61% and medication use by 38-73% in various studies), trabecular ablation with the Trabectome (23-39% and 21-43%, respectively), excisional goniotomy with the Kahook Dual Blade (15-36% and 15-40%, respectively), ab interno canaloplasty (35% and 57%, respectively), and combined canaloplasty and trabeculotomy using the OMNI system (39-40% and 64-73%, respectively). For patients who would benefit from early standalone surgery, these procedures offer meaningful reductions in both IOP and medication burden.

The Efficacy and Safety of the GATT Procedure in Open-Angle Glaucoma-6-Month Results

AIM

The aim of the study was to retrospectively evaluate the efficacy and safety of GATT during a 6-month observation period.

MATERIAL AND METHODS

The studied group consisted of 69 open-angle glaucoma patients treated with GATT as the only procedure or in combination with cataract surgery. Patients were assessed 1 day, 10 days, 1 month, 3 months, and 6 months after the surgery via standard ophthalmic examination including VF, IOP, and BCVA. The number of medications taken daily and possible complications were checked. Two criteria of success were established (S1: IOP decrease by 30% and S2: IOP lower than 18 mm Hg).

RESULTS

Before the surgery, the mean IOP was 26.94 mmHg and significantly decreased after GATT to 15.59 mmHg at 6M. BCVA did not significantly differ between the visits. The mean MD did not change significantly within the 6-month observation period (-8.20 dB vs. -8.16 dB, p = 0.9824), similar to the mean VFI (64.31% vs. 63.05%, p = 0.8571). A 30% IOP decrease at 6M visit was obtained in 95.6% of patients, and 37.7% needed medications to stabilize IOP. An IOP lower than 18 mmHg at 6M was obtained in 91.3% of studied patients after the GATT procedure, and in 58.0% without additional medications. The mean number of medications received daily decreased significantly at 6M compared to preoperative results (2.59 at inclusion vs. 0.76 at 6M, p = 0.0004). The most frequent complication after surgery was hyphema, which resolved spontaneously within 10 days.

CONCLUSION

The 6-month observation showed that GATT is a minimally invasive glaucoma-surgery technique that enables an effective and safe IOP decrease.

Minimally Invasive Glaucoma Surgery: Safety of Individual Devices

Primary open-angle glaucoma progression in those already on maximal medical therapy has traditionally been treated with trabeculectomy, a surgical procedure that carries a high degree of morbidity. In the last few decades, significant advances have been made in the field of minimally invasive glaucoma surgery (MIGS) devices, which aim to defer or prevent trabeculectomy via less arduous surgical techniques in certain types of glaucoma. Although reviews have been published examining the efficacy of various MIGS techniques, no article synthesises the comparative safety of all available devices. We performed a literature review examining the safety of MIGS devices. Fifteen devices were included, variously attempting to increase aqueous outflow through the trabecular meshwork or the suprachoroidal space, shunting into the subconjunctival space, or reducing aqueous production through ciliary body ablation. Notably, the earliest product attempting to increase outflow to the suprachoroidal space, Alcon's CyPass Micro-Stent, was withdrawn from the market due to concerns regarding increased corneal endothelial cell loss at five years post-implantation. All other devices were described as well-tolerated, with the most common adverse effects including hyphaema, intraocular pressure spikes, and device migration or obstruction. MIGS devices are purported to be uniformly safe, and many studies report no statistically significant increased complications beyond those associated with cataract surgery alone. It is important to note, however, the generally poor quality of current studies, with a dearth of randomised, or even prospective, data, and a large proportion of studies funded by device producers.

Canaloplasty and trabeculotomy with the OMNI® surgical system in OAG with prior trabecular microbypass stenting

Purpose

Evaluate effectiveness and safety outcomes for patients treated with canaloplasty and trabeculotomy previously treated with a trabecular microbypass stent (TBS).

Methods

Retrospective, multicenter, IRB approved study. Patients treated with TBS (iStent/iStent inject, Glaukos) and subsequently with OMNI surgical system (OSS) (Sight Sciences). From 5 practices in 5 US states. Open-angle glaucoma (OAG), minimum 3 months follow-up after OSS surgery, Pre-OSS IOP ≥ 17 mmHg on ≥ 1 medication. No glaucoma procedures between TBS and OSS. Endpoints: proportion with ≥ 20% reduction in IOP, IOP between 6 and 18 mmHg, mean IOP, change in IOP, mean number of medications. Adverse events and secondary surgical interventions (SSI). Mann–Whitney rank sum test compared pre-OSS IOP and medications with follow-up.

Results

Twenty seven patients. Average age (SD) 72.2 (10.8), 22/27 primary OAG (82%), mean MD − 6.2 (7.0) dB. Mean IOP before OSS 22.3 (4.3) mmHg on 2.2 (1.3) medications. At last follow-up (mean 11 months) IOP was 17.2 mmHg on 1.8 medications, − 5.1 mmHg (− 23%, p < .001), − 0.4 meds (− 18%, p = .193); ≥ 20% IOP reduction (41%), IOP ≤ 18 (56%). Adverse events were non-serious. Hyphema > 1 mm (3, 11%), BCVA decrease (4, 15%), IOP spike (2, 7%). SSI (4, 15%) had higher pre-OSS IOP (23.4 mmHg) and worse MD (− 9.6 dB).

Conclusion

Patients uncontrolled by medication and a prior TBS would once have been candidates for trabeculectomy and tube shunts. OSS offered a minimally invasive option that provided IOP control and avoidance of traditional surgery for the majority over follow-up averaging 11 months and up to 42 months.

Canaloplasty and Trabeculotomy Combined with Phacoemulsification for Glaucoma: 12-Month Results of the GEMINI Study

Purpose

To report 12-month efficacy outcomes of 360° canaloplasty and 180° trabeculotomy using the OMNI surgical system in combination with phacoemulsification in patients with mild-moderate open-angle glaucoma (OAG) and visually significant cataract.

Setting

Fifteen multi-subspecialty ophthalmology practices and surgery centers located in 14 US states.

Design

Prospective, multicenter, IRB approved study of patients treated with canaloplasty (360°) and trabeculotomy (180°). Eligible patients had cataract and mild-moderate OAG with intraocular pressure (IOP) ≤33 mmHg on 1 to 4 hypotensive medications. Unmedicated post-washout mean diurnal IOP (DIOP) ≥21 and ≤36 mmHg.

Methods

Medication washout preoperatively and prior to month 12 DIOP. Effectiveness outcomes were IOP and IOP lowering medication use. Safety outcomes included adverse events and secondary surgical interventions (SSIs). Evaluations at 1, 3, 6, and 12 months.

Results

A total of 149 subjects underwent surgery and 120 were included in the final effectiveness analysis. Mean (standard deviation) unmedicated diurnal IOP was reduced from 23.8 (3.1) mmHg at baseline to 15.6 (4.0) at month 12 (−35%) and medications (before washout) were reduced from 1.8 (0.9) at baseline to 0.4 (0.9) at month 12 (−80%). At month 12, 84.2% of eyes achieved IOP reductions >20% from baseline, 80% of eyes were medication-free, and 76% of eyes achieved IOP between 6–18 mmHg inclusive. Adverse events were uncommon. Most were mild and self-limited including transient hyphema (9 of 149; 6%) and transient IOP elevations (3 of 149; 2.0%). No eyes required SSIs or experienced loss of VA that was attributable to the device or procedure.

Conclusion

Canaloplasty and trabeculotomy performed with the OMNI surgical system at the time of phacoemulsification significantly reduces unmedicated mean diurnal IOP and medication use 12 months postoperatively, with an excellent safety profile. This procedure should be considered for eyes with mild-moderate OAG to reduce IOP, medication burden, or both.

A novel use of the endoscopic cyclophotocoagulative probe for the management of excisional goniotomy induced chronic recurrent hyphema

Purpose

To describe the management of a case of chronic, recurrent hyphema following excisional goniotomy with the Kahook Dual Blade.

Observations

One week following uncomplicated surgery, the patient presented with eye pain, elevated intraocular pressure, and layered hyphema. The hyphema resolved with conservative measures but recurred several times with similar symptoms over the next several months. An attempt to stenose the "oozing" collector channel using the argon laser was unsuccessful. Treatment of the angle with an endoscopic semi-conductor diode laser (endoscopic cyclophotocoagulative or ECP) probe successfully altered the angle preventing further episodes of recurrent hyphema. The primary glaucoma procedure failed necessitating a filtering procedure.

Conclusions and importance

Clinician should be aware of this potential complication, its treatment options, and outcomes.

360° Ab-Interno Schlemm's Canal Viscodilation with OMNI Viscosurgical Systems for Open-Angle Glaucoma-Midterm Results

Purpose: To evaluate the effectiveness of ab-interno microcatheterization and 360° viscodilation of Schlemm’s canal (SC) performed with OMNI viscosurgical system in open angle glaucoma (OAG) together or not with phacoemulsification. Setting: Two surgical sites. Design: Retrospective, observational. Methods: Eighty eyes from 73 patients with mild to moderate OAG underwent ab- interno SC viscodilation performed with OMNI system. Fifty eyes (Group 1) underwent only SC viscodilation, while 30 eyes (Group 2) underwent glaucoma surgery + cataract extraction. Primary success endpoint at 12 months was an intraocular pressure (IOP) reduction higher than 25% from baseline with an absolute value of 18 mmHg or lower, either on the same number or fewer ocular hypotensive medications, without further interventions. Secondary effectiveness endpoints included mean IOP, number of medications and comparison of outcomes between groups. Safety endpoints consisted of best-corrected visual acuity (BCVA), adverse events (AEs), and subsequent surgical procedures. Results: Primary success was achieved in 40.0% and 67.9% in Groups 1 and 2, respectively. Mean IOP at 12-month follow-up showed a significant reduction in both groups (from 23.0 to 15.6 mmHg, p < 0.001, and from 21.5 to 14.1, p < 0.001, in Groups 1 and 2, respectively). Mean medication number decreased in both groups (from 3.0 to 2.0, p < 0.001 and from 3.4 to 1.9, p < 0.001, in Groups 1 and 2, respectively). AEs included hyphema (2 eyes), mild hypotony (4 eyes), IOP spikes one month after surgery (1 eye). Twelve eyes (15.0%) required subsequent surgical procedures. No BCVA reduction was observed. Conclusions: Viscodilation of SC using OMNI viscosurgical systems is safe and relatively effective in reducing IOP in adult patients with OAG.

Outcomes of gonioscopy-assisted transluminal trabeculotomy in juvenile-onset primary open-angle glaucoma

PURPOSE

To report the outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) for juvenile-onset primary open-angle glaucoma (JOAG).

METHODS

A consecutive case series of JOAG patients who underwent GATT was reviewed with follow-up period of up to 18 months. Intraocular pressure (IOP), number of glaucoma medications and success rate were compared between eyes with and without prior glaucoma surgery, and between mild-to-moderate and severe cases defined based on Humphrey Visual Field mean deviation.

RESULTS

In total, 59 eyes of 48 patients were included. Overall, IOP was reduced from 26.5 ± 9.0 mmHg on 3.7 ± 0.9 medications preoperatively to 14.7 ± 3.0 mmHg on 0.7 ± 1.2 medications at 12 months and to 14.1 ± 2.3 mmHg on 0.4 ± 0.8 medications at 18 months postoperatively (P < 0.001). The complete and qualified success rates were 70.8% and 81.2% at 12 months, and 58.6% and 81.2% at 18 months, respectively. Eyes with and without prior glaucoma surgery did not differ significantly in terms of postoperative IOP, glaucoma medication and success rate. In addition, GATT was effective for both mild-to-moderate and severe cases; the latter achieved a surgical success of 79.1%.

CONCLUSIONS

GATT is effective for JOAG. In particular, this case series suggests that GATT is promising in treating severe JOAG and those with prior glaucoma surgery.

Canaloplasty and trabeculotomy ab interno with the OMNI system combined with cataract surgery in open-angle glaucoma: 12-month outcomes from the ROMEO study

PURPOSE

To provide safety and effectiveness outcomes 12 months postsurgically for sequential canaloplasty and trabeculotomy with the OMNI system combined with cataract surgery in mild-to-moderate open-angle glaucoma (OAG).

SETTING

Eleven ophthalmology practices and surgery centers located in 8 U.S. states.

DESIGN

Retrospective, multicenter, single arm.

METHODS

Twelve surgeons contributed 81 patients meeting eligibility criteria: OAG, 12-month follow-up, and medicated intraocular pressure (IOP) 36 mm Hg or less on 4 or less medications preoperatively. Analysis was stratified by baseline IOP: more than 18 mm Hg (Group 1) and 18 mm Hg (Group 2) or less. Success was defined as proportion with 20% reduction or greater in IOP or IOP between 6 and 18 mm Hg (inclusive) and on the same or fewer medications without secondary surgical intervention (SSI). Other endpoints included mean IOP and medications at 12 months. Safety included corrected distance visual acuity and adverse events (AEs).

RESULTS

Of the 81 patients included, primary success was met by 79% in Group 1 and 81% in Group 2. The mean IOP was reduced in Group 1 (21.9 to 15.1 mm Hg, P < .0001) and remained controlled in Group 2 (14.1 to 13.4 mm Hg, P = .3177). Medications went from 2.0 ± 1.3 to 1.1 ± 1.1 in Group 1 and from 1.6 ± 1.3 to 0.9 ± 1.2 in Group 2. AEs were typical for cataract or angle surgery: mild inflammation (11%), IOP spikes (5%), and hyphema (4%). Four patients (5%) required an SSI.

CONCLUSIONS

The OMNI system provided effective IOP reduction, sustained IOP control, and meaningful medication reduction for up to 12 months postoperative.

Modeling the effects of glaucoma surgery on intraocular pressure

Minimally invasive glaucoma surgeries (MIGS) offer an effective way to lower intraocular pressure without inducing extensive trauma to the anterior segment. In order to predict their efficacy, an analytical model of the conventional aqueous humor outflow pathway is developed using a resistor network. The model describes outflow through the normal eye and allows for the effects of geometric changes in the outflow pathway as IOP changes. By selectively removing these resistors, the model can be used to examine and predict the outcomes of several surgical procedures currently used to treat glaucoma. Treatments examined include traditional trabeculectomy, several ab interno methods for trabeculotomy and trabeculectomy, as well as recently developed trabecular stents that bypass the trabecular meshwork and dilate Schlemm canal. The model's predictions for the efficacy of these procedures generally matched well with the efficacy determined in experimental studies, although it tended to somewhat overestimate the efficacy of these procedures. Matching the model to experimental data indicated that a partial trabeculotomy substantially increases flow to collector channels within that region and approximately 1.5 clock hours past the ends of the trabeculotomized region. Similarly, trabecular bypass stents substantially increase flow to collector channels up to 1.5 clock hours past the open ends of the stent. The resistor model we have developed can be used to predict the efficacy of a variety of MIGS procedures. Circumferential flow in Schlemm canal extends the efficacy of MIGS, but this effect is limited to a few clock hours.

12-month interim results of a prospective study of patients with mild to moderate open-angle glaucoma undergoing combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery

PURPOSE

To characterize clinical outcomes of combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery in eyes with mild to moderate open-angle glaucoma (OAG).

METHODS

In this prospective case series, the OMNI glaucoma surgical platform (Sight Sciences, Menlo Park, CA) was utilized to perform the procedure either combined with phacoemulsification or as a standalone procedure. Changes from baseline in intraocular pressure (IOP) and IOP-lowering medications were evaluated through the first 12 months of a planned 24-month follow-up period.

RESULTS

Among 17 eyes of 15 subjects, mean IOP was reduced from 20.4 mmHg to 12.7-13.7 mmHg through 12 months of follow-up (p < 0.001 at every time point) and mean medications reduced from 2.5 to 0.1-0.6 (p < 0.001 at every time point). IOP reductions in eyes undergoing standalone surgery were approximately 2-4 mmHg greater at each time point compared to eyes undergoing surgery combined with phacoemulsification; this may be related to a higher baseline IOP in the former eyes (22.1 vs 18.5 mmHg). Six eyes developed hyphema, of which three required washout for elevated IOP on the first postoperative day; six additional eyes had IOP elevations that resolved with medical management.

CONCLUSION

Viscodilation of Schlemm's canal and collector channels paired with ab interno trabeculotomy performed with a single integrated instrument (OMNI), whether as standalone or combined with phacoemulsification, effectively lowers both IOP and the need for IOP-lowering medications through 12 months of follow-up.

Canaloplasty and Trabeculotomy Combined with Phacoemulsification in Open-Angle Glaucoma: Interim Results from the GEMINI Study

PURPOSE

To report interim 6-month safety and efficacy outcomes of 360° canaloplasty and 180° trabeculotomy using the OMNI® Surgical System concomitantly with phacoemulsification in patients with open-angle glaucoma (OAG).

SETTING

Fifteen multi-subspecialty ophthalmology practices and surgery centers located in 14 states (Alabama, Arizona, Arkansas, Florida, Georgia, Iowa, Kansas, Montana, Nebraska, North Dakota, Oklahoma, Pennsylvania, Texas, and Wisconsin).

DESIGN

Prospective, multicenter, IRB approved study of patients treated with canaloplasty (360°) and trabeculotomy (180°). Eligible patients had cataract and mild-moderate OAG with intraocular pressure (IOP) ≤33 mmHg on 1 to 4 hypotensive medications.

METHODS

Medication washout prior to baseline diurnal IOP (Goldmann). Effectiveness outcomes included mean IOP and medications. Safety outcomes included adverse events (AE), best corrected visual acuity (BCVA) and secondary surgical interventions (SSI). Analysis includes descriptive statistics and t-tests evaluating change from baseline.

RESULTS

A total of 137 patients were enrolled and treated. Mean diurnal IOP after washout was 23.8 ± 3.1 mmHg at baseline. At month 6, 78% (104/134) were medication free with IOP of 14.2 mmHg, a mean reduction of 9.0 mmHg (38%). 100% (104/104) had a ≥ 20% reduction in IOP and 86% (89/104) had IOP ≥6 and ≤18 mmHg. The mean number of medications at screening was 1.8 ± 0.9 and 0.6 ± 1.0 at month 6. AE included transient hyphema (4.6%) and IOP elevation ≥10 mmHg (2%). There were no AE for loss of BCVA or recurring hyphema. There were no SSI.

CONCLUSION

Canaloplasty followed with trabeculotomy and performed concomitantly with phacoemulsification has favorable intra and perioperative safety, significantly reduces IOP and anti-glaucoma medications through 6 months in eyes with mild-moderate OAG.

Comparison of Gonioscopy-assisted Transluminal Trabeculotomy Versus Trabeculectomy With Mitomycin C in Patients With Open-angle Glaucoma

PRCIS

Trabeculectomy (TRAB) lowers the intraocular pressure (IOP) more than gonioscopy-assisted transluminal trabeculotomy (GATT) at 18 months, with a reduction in IOP of 30% or more and a significant reduction in the number of glaucoma medications compared with baseline.

PURPOSE

To compare the IOP-lowering efficacy of GATT with mitomycin-C augmented TRAB in patients with uncontrolled open-angle glaucoma.

METHODS

Single-center, retrospective, comparative cohort study. One hundred ten consecutive patients (110 eyes) underwent GATT (n=61) or TRAB (n=49). The primary outcome measure was IOP reduction, defined as a percentage decrease ≥30% and absolute IOP≤18 mm Hg at 18 months with (qualified) or without (complete) medications. Secondary outcomes were visual field change, number of glaucoma medications, complications, and reintervention.

RESULTS

The mean±SD baseline IOP was 30.04±7.5 and 27.59±4.70 (P=0.072) with the mean number of medications of 3.08±0.73 and 2.92±0.91 (P=0.310) in TRAB and GATT, respectively. At 18 months, the mean±SD IOP was 15.26±3.47 mm Hg and 12.48±4.58 mm Hg after GATT and TRAB, respectively (P=0.002). The percentage of IOP lowering from baseline was 56.05±17.72 after TRAB and 42.04±15.56 after GATT (P<0.001). Percentages of complete and qualified success were 59% and 27% after TRAB and 46% and 31% after GATT (P=0.353). No change in visual field loss was observed in both groups. The mean reduction in medications was 2.3±1.4 and 2.1±1.5 in TRAB and GATT, respectively (P=0.493). The most frequent complication after TRAB was hypotony and after GATT hyphema. Reintervention occurred in 8.2% of cases after TRAB and in 14.8% after GATT (P=0.341).

CONCLUSIONS

IOP lowering was greater after TRAB than after GATT at 18 months with a significant reduction in the number of medications after both procedures. Complications and reintervention occurred equally in both groups but differed in type.

A novel suprachoroidal microinvasive glaucoma implant: in vivo biocompatibility and biointegration

Background

A major challenge for any glaucoma implant is their ability to provide long-term intraocular pressure lowering efficacy. The formation of a low-permeability fibrous capsule around the device often leads to obstructed drainage channels, which may impair the drainage function of devices. These foreign body-related limitations point to the need to develop biologically inert biomaterials to improve performance in reaching long-term intraocular pressure reduction. The aim of this study was to evaluate in vivo (in rabbits) the ocular biocompatibility and tissue integration of a novel suprachoroidal microinvasive glaucoma implant, MINIject™ (iSTAR Medical, Wavre, Belgium).

Results

In two rabbit studies, no biocompatibility issue was induced by the suprachoroidal, ab-externo implantation of the MINIject™ device. Clinical evaluation throughout the 6 post-operative months between the sham and test groups were similar, suggesting most reactions were related to the ab-externo surgical technique used for rabbits, rather than the implant material itself. Histological analysis of ocular tissues at post-operative months 1, 3 and 6 revealed that the implant was well-tolerated and induced only minimal fibroplasia and thus minimal encapsulation around the implant. The microporous structure of the device became rapidly colonized by cells, mostly by macrophages through cell migration, which do not, by their nature, impede the flow of aqueous humor through the device. Time-course analysis showed that once established, pore colonization was stable over time. No fibrosis nor dense connective tissue development were observed within any implant at any time point. The presence of pore colonization may be the process by which encapsulation around the implant is minimized, thus preserving the permeability of the surrounding tissues. No degradation nor structural changes of the implant occurred during the course of both studies.

Conclusions

The novel MINIject™ microinvasive glaucoma implant was well-tolerated in ocular tissues of rabbits, with observance of biointegration, and no biocompatibility issues. Minimal fibrous encapsulation and stable cellular pore colonization provided evidence of preserved drainage properties over time, suggesting that the implant may produce a long-term ability to enhance aqueous outflow.

Microinvasive glaucoma surgery: A review of 3476 eyes

Microinvasive glaucoma surgery (MIGS) is a potentially safer and more efficacious method studied in patients with mild-to-moderate open-angle glaucoma requiring less invasive treatment goals; however, the literature on MIGS must be thoroughly evaluated. We conducted a review of MIGS by searching MEDLINE, EMBASE, and Cochrane CENTRAL. Primary efficacy indicators were reductions in intraocular pressure and topical medication use postoperatively. While all comparative randomized controlled trials assessing MIGS in English peer-reviewed journals were included, only observational studies with a target follow-up of at least one year and a high priority score were analyzed, resulting in a total of 3476 eyes across 20 trials. The mean age was 69.5 ± 2.9 years, 53.7% were female, and 77.4% were Caucasian. One study had last follow-up at less than one year, fifteen studies had follow-up extending 1-2 years, and four had longer than two years of follow-up. A pattern of more significant intraocular pressure and medication reduction was observed in patients who underwent MIGS (n = 2170) relative to control (n = 1306) interventions. iStent had the most literature supporting its efficacy, followed by Hydrus. The most common adverse events after MIGS implantation included stent obstruction, inflammation, and subsequent surgical intervention. Surgical complication rates and efficacy are favorable after MIGS. This review helps to consolidate the high-quality evidence that exists for various MIGS procedures and to identify gaps where further research is needed.

Twelve-Month Outcomes of Stand-Alone Excisional Goniotomy in Mild to Severe Glaucoma

PURPOSE

To describe 12-month intraocular pressure (IOP) and medication use outcomes following excisional goniotomy (EG) as a stand-alone procedure in eyes with medically uncontrolled glaucoma.

METHODS

This was a retrospective analysis of data from surgeons at 8 centers (6 US, 2 Mexico). Eyes with glaucoma undergoing standalone EG with a specialized instrument (Kahook Dual Blade, New World Medical, Rancho Cucamonga, CA) for IOP reduction and followed for 12 months postoperatively were included. Data were collected preoperatively, intraoperatively, and 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. The primary outcome was reduction from baseline in IOP, and key secondary outcomes included IOP-lowering medication reduction as well as adverse events.

RESULTS

A total of 42 eyes were analyzed, of which 36 (85.7%) had mild to severe primary open-angle glaucoma (POAG). Mean (standard error) IOP at baseline was 21.6 (0.8) mmHg, and mean number of medications used at baseline was 2.6 (0.2). At 3, 6, and 12 months postoperatively, mean IOP reductions from baseline were 4.6 mmHg (22.3%), 5.6 mmHg (27.7%), and 3.9 mmHg (19.3%) (p≤0.001 at each time point). At the same time points, mean medications reductions of 0.7 (25.8%), 0.9 (32.6%), and 0.3 (12.5%) medications were seen (p<0.05 at months 3 and 6, not significant at month 12). Six eyes (14.3%) underwent additional glaucoma surgery during the 12-month follow-up period.

DISCUSSION

Standalone EG with KDB can reduce IOP, and in many cases reduce medication use, through up to 12 months in eyes with mild to severe glaucoma. Statistically significant and clinically relevant reductions in IOP were seen at every time point. While the goal of surgery was not to reduce medication burden, mean medication use was significantly reduced at all but the last time point. In the majority of eyes, the need for a bleb-based glaucoma procedure was delayed or prevented for at least 12 months.

Circumferential canal surgery: a brief history

PURPOSE OF REVIEW

Most microinvasive glaucoma surgery (MIGS) procedures bypass outflow resistance residing proximally in the trabecular meshwork and inner wall of Schlemm's canal. A novel procedure combining trabeculotomy with viscodilation adds to this by also addressing distal resistance of the canal and collector channel ostia. This review examines the development and evidence for both trabeculotomy and canaloplasty separately and the combination in a single procedure.

RECENT FINDINGS

Recent aqueous angiography studies have confirmed the segmental nature of outflow through Schlemm's canal highlighting the need to address distal outflow pathway resistance. Combined trabeculotomy and viscodilation ab interno is a novel approach with a new purpose-designed device (OMNI Surgical System) becoming available to surgeons in early 2018. Recent results as both a standalone and combined with cataract procedure demonstrate significant intraocular pressure reductions with an average 41% reduction from baseline in the pseudophakic group.

SUMMARY

Targeting both distal as well as proximal points of outflow resistance in the conventional pathway may prove to be a highly efficacious MIGS modality. Additional large prospective studies are currently ongoing to confirm these preliminary results.

Comparison Of Surgical Outcomes Of 360° Circumferential Trabeculotomy Versus Sectoral Excisional Goniotomy With The Kahook Dual Blade At 6 Months

Purpose

To compare reductions in intraocular pressure (IOP) and IOP-lowering medication use following sectoral excisional goniotomy with the Kahook Dual Blade (KDB) or 360° trabeculotomy (via either Trab360 or gonioscopy-assisted transluminal trabeculotomy [GATT]) in eyes with open-angle glaucoma (OAG) undergoing phacoemulsification cataract surgery.

Methods

A retrospective review was conducted to collect data from adult subjects with early to advanced primary or secondary OAG undergoing phacoemulsification combined with either KDB or 360° trabeculotomy (Trab360 or GATT) between August 1, 2016 and July 30, 2018 for which 6-month follow-up was available. Data collected included IOP, glaucoma medications, adverse events, and additional IOP-lowering procedures. The primary outcome measure was surgical success (≥20% IOP or ≥1 medication reduction without additional IOP-lowering procedures) at 6 months.

Results

Data were collected from 74 eyes of 61 subjects undergoing KDB excisional goniotomy and 27 eyes of 25 subjects undergoing 360° trabeculotomy (19 eyes of 17 subjects undergoing Trab360 and 8 eyes of 8 subjects undergoing GATT). At 6 months, 81.7% (58/71) of KDB eyes and 84.6% (22/26) of 360° trabeculotomy eyes achieved surgical successes (P=0.737). Mean IOP reductions and medication reductions were similar between groups at 6 months. However, more eyes undergoing KDB than Trab360/GATT achieved target IOP ≤18 mmHg (80.0% [56/70] vs 59.3% [16/27], P=0.040) and ≤15 mmHg (61.4% [43/70] vs 25.9% [7/27], P=0.003) without further IOP-lowering interventions at 6 months. The nature and frequency of adverse events were similar between groups.

Conclusions

Both KDB and Trab360 or GATT procedures similarly lowered both IOP and the need for IOP-lowering medications during the first 6 postoperative months. More eyes undergoing KDB excisional goniotomy than 360° trabeculotomy attained target IOP ≤18 mmHg and ≤15 mmHg at 6 months. A full 360° trabecular bypass may not be necessary to achieve maximal efficacy from this class of micro-invasive glaucoma procedures.