One-year outcomes of Bent ab-interno needle goniectomy with phacoemulsification in primary glaucoma

Abstract

Purpose:

To study 1-year outcomes of bent ab-interno needle goniectomy (BANG) with phacoemulsification in patients across the glaucoma spectrum.

Methods:

This Prospective, noncomparative interventional study enrolled primary glaucoma patients (open-angle and angle-closure) with medically controlled intraocular pressure (IOP) and visually significant cataracts who underwent clear corneal phacoemulsification with intraocular lens placement combined with BANG using a 25-gauge needle bent as a reverse cystitome. Patients completing a minimum 1-year post-surgical follow-up were analyzed. The primary outcome was the change in antiglaucoma medications (AGM) required after surgery. Complete and qualified success was defined as IOP between 6 and 21 mm Hg without and with up to two topical AGMs.

Results:

Thirty eyes of 30 patients with a mean age of 60.5 ± 10.3 years were analyzed. The mean baseline IOP was 15.3 ± 3.6 mmHg, and the mean number of topical AGM was 2.6 ± 1.3. Ten patients were on systemic acetazolamide. The topical AGM requirement decreased to 0.60 ± 0.99 (P < 0.0001) and 0.87 ± 1.02 (P < 0.0001) at 6 months and 1 year, respectively. The mean IOP decreased to 13.57 ± 2.79 (P = 0.028) and 14.43 ± 2.92 mmHg (P = 0.11) at 6 months and 1 year, respectively. No patient required oral acetazolamide at the 6-month and 1-year follow-up after surgery. At 1-year, complete and qualified success was seen in 14 eyes each. Six eyes (20%) had an episode of a transient IOP spike, which resolved in 2 weeks, and one eye had hyphema, which resolved by the fourth day. There were no serious complications.

Conclusions:

Phacoemulsification with BANG is an effective and safe procedure for reducing the medication burden in patients with primary glaucoma.

Cataracts and glaucoma are two of the leading causes of moderate and severe visual impairment, the prevalence of which has increased substantially as the population ages.[1] Since both conditions are age-related, they often occur concomitantly in many patients. Visual impairment due to cataracts is reversible, while glaucoma, being a group of progressive optic neuropathies, can lead to irreversible vision loss if left untreated. The management of individuals with both cataracts and glaucoma poses a complex clinical challenge, as addressing one condition may exacerbate the other.[2]

Since the only known modifiable risk factor for glaucoma is raised intraocular pressure (IOP), lowering it is the mainstay of medical and surgical glaucoma therapy.[3] However, long-term topical antiglaucoma medication (AGM) use is associated with ocular surface disease,[4,5] and is uncomfortable for patients, thereby reducing compliance. Additionally, chronic inflammation may also reduce the potential benefit of future incisional surgery due to excessive subconjunctival fibrosis.[6] In the past decade, there has been renewed interest in strategies to minimize AGM dependence while maintaining acceptable IOP control.

Minimally invasive glaucoma surgery (MIGS) refers to a diverse group of relatively new procedures that lower IOP with limited or no disruption to the conjunctiva or sclera.[7] Although they are known to have a higher safety profile than conventional filtration surgery, the IOP-lowering efficacy is lesser, and their long-term results are still being determined. MIGS has become widely used in standard glaucoma care, especially when combined with phacoemulsification.[8,9] Some of these procedures involve the implantation of devices, which usually entails a hefty cost that is not affordable in underserved areas.[10]

The inner wall of Schlemm’s canal and juxtacanalicular TM are the main sites of resistance to aqueous outflow.[11] TM stripping instruments like the Kahook dual blade (KDB, New World Medical Inc., Rancho Cucamonga, CA) or the Trabectome (Neomedix Corporation, Tustin, CA) work on the principle of removing functional TM to allow egress of aqueous directly through the Schlemm’s canal into the episcleral collector channels.[12,13] Recently, there have been a few reports on the Tanito microhook (µLOT), which works similarly, and preliminary studies report good outcomes.[14,15]

To counter the high cost of this technology while targeting the TM region, Kim et al.[16] and Eslami et al.[17] described their early results of a conventional needle goniotomy, which was analogous to the procedure described by Barkan in 1942,[18] now mainly used for congenital glaucoma. Shute et al.[19] described the bent ab-interno needle goniectomy (BANG) procedure and reported early efficacy at 3 months when used with phacoemulsification. The BANG technique uses a standard hypodermic needle modified like a reverse cystotome with sharp edges, excising a trabecular meshwork strip as the KDB does.

This paper demonstrates the utility of adding BANG at the time of phacoemulsification in glaucoma patients with cataracts in terms of reduced dependence on AGMs 1 year after the procedure.

Methods

This noncomparative case series evaluated the efficacy and outcomes of BANG added to phacoemulsification (Phaco-BANG) in patients with medically controlled glaucoma and cataracts. The principal study question was whether Phaco-BANG could effectively reduce AGM dependence in various forms of glaucoma and potentially avoid subsequent filtration surgery in patients requiring oral acetazolamide. Ethical approval was obtained from the Institutional Ethics Committee of the Postgraduate Institute of Medical Education and Research, Chandigarh, and the study was conducted following the principles of the Declaration of Helsinki.

Adult glaucoma patients (>18 years of age) with medically controlled IOP and visually significant cataracts who fulfilled the inclusion criteria were included in the study. Eligible participants were recruited from the glaucoma services of a tertiary teaching institute in North India between March 2022 and October 2022. Each patient underwent a comprehensive ophthalmic examination, including best-corrected visual acuity (BCVA), IOP measured by Goldmann applanation tonometry (GAT), slit-lamp biomicroscopy, gonioscopy, stereoscopic disc evaluation using a 90.0-D lens, and a reliable visual field (VF) test by Humphrey’s VF analyser750 II (Carl Zeiss-Humphrey Systems, Dublin, CA) using the 24-2 protocol A VF test was defined as reliable when fixation losses were less than 20%, and false-positive and false-negative rates were less than 33%.[20] Informed consent was obtained from eligible participants before their inclusion in the study.

To be eligible for inclusion, patients had to fulfil the following inclusion criteria: BCVA < 6/12 attributable to age-related cataract, clear cornea with an unobstructed view of the angle on gonioscopy, IOP < 21 mm Hg on AGMs, and systemic fitness for surgery under local anesthesia. Primary open-angle glaucoma (POAG), primary angle closure disease (PACD), and pseudoexfoliative glaucoma (PEXG) were included. PACD eyes were included if they had a patent laser iridotomy and visibility of the posterior pigmented trabecular meshwork on indentation gonioscopy in at least 120 degrees of the nasal quadrant. The exclusion criteria included patients with secondary closed-angle glaucoma, prior intraocular surgery, those on blood thinners for coronary artery disease or stroke, patients with active uveitis, anticipated need for combined ocular procedures, or those allergic to xylocaine.

The data of patients completing a minimum 1-year postoperative follow-up were analyzed.

All participants underwent clear cornea phacoemulsification combined with BANG (Phaco-BANG), performed by one of three experienced surgeons (SK, FT, SSP). The detailed procedure is summarized below.

Following peribulbar anesthesia and standard sterile eye preparation, the BANG was completed before phacoemulsification. A 1.2-mm paracentesis was created temporally in the clear cornea to access the nasal angle, taking care to enter anterior to any limbal blood vessels. Dispersive viscoelastic (Aurovisc, Hydroxy propyl methyl cellulose solution 2% w/v, Auro Laboratories Limited, Madurai, India) was used to fill the anterior chamber and coat the corneal endothelium. The patient’s head and operating microscope were rotated to aid visualization of the angle structures. A Swan Jacob gonioprism, gently resting on a bed of cohesive viscoelastic (Cohevisc 1.4, Sodium Hyaluronate 1.4%, Appasamy Ocular Device Pvt Ltd, Chennai, India) on the cornea, was used to view the angle. A goniotome was fashioned by bending the distal 1.0 mm of a sterile 25-gauge one-inch hypodermic needle toward the bevel using a needle holder [Fig. 1a and b]. The bent goniotome was mounted on a viscoelastic-filled syringe and inserted through the port, holding the bevel sideways and not injuring surrounding tissues. The angle structures were identified, and the needle tip was engaged into the pigmented trabecular meshwork [Fig. 1c]. The nasal 100–120 degrees of TM was excised [Fig. 1d]. All patients had at least 100 degrees excised, determined by direct visualization of at least 2-clock h treated on either side of the center. Since the eligibility for inclusion for PACG patients included visibility of the nasal angle, goniosynechiolysis was not performed on any patient to ensure uniformity of the surgical technique.

Figure 1.

Surgical technique of bent ab-interno needle goniectomy (BANG). a, b 25-gauge hypodermic needle being bent as a reverse cystitome. c. The bent needle tip is engaged into the trabecular meshwork. d. Schlemm’s canal opened, and the iris receded posteriorly after BANG

The head and microscope were straightened, and a standard clear corneal phacoemulsification with a posterior chamber intraocular lens was completed. The paracentesis created for the BANG was used as one of the ports for the cataract surgery. In the case of hyphemia, the irrigation continued until the blood was cleared from the anterior chamber. At the end of the surgery, each wound was verified as watertight, and a subconjunctival antibiotic plus steroid was administered.

Postoperatively, the patients were instructed to keep their heads tilted toward the side of the surgery to ensure any hyphemia would be directed away from the raw incised area. All patients were prescribed betamethasone sodium phosphate 0.1% six times a day for 4 weeks and moxifloxacin 0.3% drops q.i.d. for 2 weeks. Betamethasone drops were then tapered weekly and stopped.

Follow-up appointments were scheduled to assess the requirement of AGMs after the procedure and IOP control. Enrolled patients were evaluated on follow-up visits on 1 day, 1 week, 4 weeks, 3 months, 6 months, and 1 year after surgery, with intervening visits scheduled as required. At every visit, IOP (measured by GAT), the number of AGMs, visual acuity, any complications, and interventions were recorded. AGMs were restarted or increased depending on the patient’s target IOP. Prostaglandin analogues were avoided within the first 6 postoperative weeks.

The primary outcome measure was the proportion of participants who did not require medication to lower IOP after surgery (drop-freedom).[19] Secondary outcome measures included the mean change in IOP, the number of AGMs required, and the proportion of participants requiring additional glaucoma procedures or experiencing intraoperative or postoperative complications.

Success was defined as per the recent recommendations for surgical success of MIGS with cataract, as defined by the American Academy of Ophthalmology’s Glaucoma Preferred Practice Pattern Committee.[21] (A decrease in glaucoma medical therapy of 1 medication or more from baseline without an increase in IOP, or IOP of 21 mmHg or less and reduced by 20% or more from baseline without an increase in glaucoma medications, additional laser or incisional glaucoma surgery, loss of light perception, vision, or hypotony). Eyes free of medical therapy to achieve an IOP between 6–21 mm Hg were considered complete successes, while those requiring up to two topical medications were considered qualified successes.

Failure was defined as IOP either >21 mmHg or <6 mmHg, or less than 20% reduction relative to baseline IOP with the same number of AGMs at two consecutive follow-up visits after 3 months. The need for additional glaucoma surgery and any complications were also defined as failure. Hyphema, defined as any amount of blood seen in the anterior chamber, was considered a serious complication when it required washout—either because it did not resolve within the first two weeks or if there was a total hyphema. Other serious complications were considered any condition of the eye that may lead to loss of light perception, vision, or hypotony, such as retinal detachment, vitreous hemorrhage, persistent choroidal detachment, or endophthalmitis.

Patient demographic information, preoperative characteristics, intraoperative details, and postoperative outcomes were recorded in standardized proformas. Descriptive statistics were used to summarize the demographic and clinical characteristics of the study population. Continuous variables were presented as mean ± standard deviation. Categorical variables were reported as frequencies and percentages. The Wilcoxon signed-rank test was used to assess changes in AGM use and IOP from baseline. Logistic regression analysis was used to identify any baseline factors for success. Kaplan–Meier plots assessed the procedure’s success in different patients. Statistical significance was set at P < 0.05.

Results

Data from 30 eyes of 30 patients who met the inclusion criteria were analyzed. Demography and baseline characteristics are depicted in Table 1. The mean age of the patients was 60.5 ± 10.3 years, the mean IOP was 15.3 ± 3.6, and the mean number of AGM used was 2.6 ± 1.2. Ten patients were on systemic acetazolamide. Fourteen eyes had POAG, and eleven had PACD. Ten, nine, and eleven eyes had mild (MD > −6 dB), moderate (MD 6–12 dB), and advanced glaucoma (MD < −12 dB), respectively.

Table 1.

Demography and baseline ocular characteristics

Diagnosis*	Age (years) (Mean±SD)	Gender (M: F)	IOP$ (mmHg (Mean±SD)	Topical AGM# No. (Mean±SD)	Systemic Acetazolamide No. (%)	Visual Field (Mean Deviation (dB) (Mean±SD)
POAG (n=14)	58.7±11.3	6 : 8	15.6±9.6	2.6±1.2	6/14 (42.86%)	−10.7±5.4
PACD (n=11)	61.0±9.9	4: 7	12.2±3.0	2.4±1.4	3/11 (27.27%)	−9.3±8.7
PEXG (n=3)	63.7±6.6	2 : 1	12.0±4.0	3.7±0.5	1/3 (33.33%)	−10.8±9.9
NTG (n=2)	66.5±4.5	2 : 0	16.0±7.1	2.5±1.5	0	−14.9±1.5
Total (n=30)	60.6±10.3	14: 16	15.3±3.6	2.6±1.3	10/30 (33.33%)	−10.5±7.3

*POAG: Primary open angle glaucoma, PACD: Primary angle closure disease, NTG – Normal tension glaucoma, PEXG – Pseudoexfoliation glaucoma, ^$IOP: Intraocular Pressure, ^#AGM: Anti glaucoma medications

Fig. 2 shows the AGM use and IOP after surgery. The mean number of topical AGMs required decreased from 2.6 ± 1.3 to 0.60 ± 0.99 (P < 0.0001) and 0.87 ± 1.02 (P < 0.0001) at 6 months and 1 year, respectively. The number of patients on oral acetazolamide decreased from 10 to zero. The mean IOP decreased from 15.33 ± 3.64 mmHg to 13.57 ± 2.79 (P = 0.028) and 14.43 ± 2.92 mm Hg (P = 0.11) at 6 months and 1 year, respectively.

Figure 2.

Change in Intraocular Pressure (IOP) and antiglaucoma medications (AGMs) after surgery

At 6 months, 16 (53.33%) eyes were free of AGMs, 10 (33.33%) eyes required only a single AGM, while 4 (13.33%) eyes required 2 AGMs, translating into the total success (complete plus qualified) of 96.7%. In 1 year, the corresponding figures were a complete success in 46.6% eyes and qualified success in 46.6%. None of the patients required systemic acetazolamide after the procedure.

Fig. 3 shows the Kaplan–Meier survival analysis. Patients with a mean deviation better than −12 D had a better outcome than those with an MD worse than −12 D. The mean IOP in the advanced glaucoma group was 15.5 ± 3.4 mmHg compared to 13.8 ± 2.8 mm Hg in those with moderate glaucoma (P = 0.16) at the 1-year follow–up. However, there was a significant difference in the AGMs required for IOP control in the two groups, respectively (1.3 ± 0.9 versus 0.47 ± 0.67; P = 0.03). Multiple logistic regression analysis showed the number of AGMs at baseline to be a significant factor in predicting success (P = 0.018). Age, IOP, and diagnosis appeared to have no bearing on the procedure's success.

Figure 3.

Kaplan–Meier survival analysis for the procedure shows that early-stage glaucoma had better survival at 1 year

Of the two failures, one eye required trabeculectomy, while the other had IOP > 21 mmHg on three topical medicines and needed a fourth drug. Both patients had advanced glaucoma. There was no failure due to hypotony.

Six eyes (20%) experienced a transient IOP spike within the first week, which was controlled with a short course of oral acetazolamide for 3 days. Of these, three had POAG, two had PACG, and one had PEXG. Four of the affected eyes had advanced glaucoma. Transient hyphema occurred intraoperatively in three patients and was tamponaded with dispersive viscoelastic on the table. In one of these patients, the hyphema persisted postoperatively but resolved by the fourth postoperative day. No serious complications, such as choroidal detachment, corneal injury, iridodialysis, or endophthalmitis, were observed.

Outcomes were stratified based on glaucoma diagnosis [Table 2]. PACD eyes benefited the most, with 72.7% and 63.3% free of AGM at 6 months and 1 year, respectively.

Table 2.

Post-operative outcomes at 6 months and 1 year

Diagnosis	IOP reduction at 6 months (mm Hg) (%)	AGM reduction at 6 months (No.) (%)	Eyes drop free at 6 months (No.)(%)	IOP reduction 1 year (mm Hg) (%)	AGM reduction at 1 year (No.) (%)	Eyes drop free at 1 year (No.) (%)
POAG (n=14)	3.13 (19.1%)	2.22 (79.6%)	8 (57.1%)	2.07 (12.7%)	1.86 (69.2%)	7 (50%)
PACD (n=11)	-1.72 (-13.7%)	2.2 (88.7%)	8 (72.7%)	1.81 (-14.4%)	1.85 (74.6%)	7 (63.3%)
PEXG (n=3)	6 (31%)	2.67 (66.7%)	0	4.7 (24.1%)	2.67 (66.7%)	0
NTG (n=2)	5 (29.4%)	1 (40%)	0	2 (11.7%)	1 (40%)	0

POAG: Primary open angle glaucoma, PACD: Primary angle closure disease, NTG – Normal tension glaucoma, PEXG – Pseudoexfoliation glaucoma, IOP: Intraocular Pressure, AGM: Anti glaucoma medications

Discussion

Phacoemulsification with BANG is a relatively new and innovative surgical technique that has emerged as a useful, low-cost MIGS, especially for low-resource areas with a considerable burden of undetected glaucoma.[22] Our paper demonstrates that this approach has the potential for rapid visual rehabilitation offered by phacoemulsification and effective IOP control by goniectomy, resulting in less dependence on AGMs.

Despite their promising outcomes, current MIGS technologies comprising implants like the iStent (Glaukos, San Clemente, CA, USA) and the Hydrus microstent (Ivantis, Inc, Irvine, CA, USA), and surgical instruments like the KDB, Trabectome, and the Tanito Microhook come at a high cost. Patients in the developing world do not have the paying capacity for these devices and often cannot afford medication, resulting in frequent dropout from continued care.[23,24,25] Though trabeculectomy is the traditional surgical option, due to its invasive nature and potential risks, it is usually reserved for advanced glaucoma. In this scenario, BANG offers a low-risk, economic opportunity to lower the AGM burden. Most operating facilities have easy access to 25-gauge or 24-gauge hypodermic needles, making this procedure readily available to all surgeons. In an era when MIGS is increasingly being shown to be beneficial, especially when combined with phacoemulsification,[26] having viable options for effective IOP control is essential.

BANG has emerged as a cost-effective alternative to many TM-based glaucoma procedures. The edges of the bevel of the needle form two cutting edges when bent, forming a “pseudo double blade” goniotome, which can excise tissue en bloc. The smooth part of the bent needle protects the posterior wall of Schlemm’s canal and maintains the depth of excision. Using the hypodermic needle has other advantages in terms of easy incorporation with routine cataract surgery. The needle may be easily inserted through a 1.2 mm incision, which can then be used as the side port for phacoemulsification.

Though the role of MIGS in mild to moderate POAG is well known, controlled studies may be restrictive in inclusion criteria, and only select patients are part of the study, while real-world situations may not match these restrictions required. The IOP-lowering potential of MIGS is also, at best, modest.[10] Our paper looks into the results of a low-cost MIGS that can be incorporated into every glaucoma patient undergoing cataract surgery, with the primary aim to reduce dependence on AGM. In that sense, we believe that our paper addresses a more real-world problem, which can be applied to everyday situations.

We included glaucoma of all stages since the primary aim of our study was to reduce the medication burden rather than IOP lowering. No patient was uncontrolled medically, and we wanted to see the effect of phaco-BANG in patients with advanced glaucoma, since they are more likely to require a greater number of AGMs, with the consequent detrimental effects on the ocular surface. Our patients were medically controlled before surgery, which is why there was not a very perceptible change in the IOP postoperatively. Since all patients had glaucoma and were scheduled for phacoemulsification, it gave us an excellent opportunity to combine BANG with cataract surgery in an attempt to reduce the dependence on AGM.

We included both POAG and PACG to see if any diagnosis had any bearing on the outcome. Even though traditional angle procedures are reserved for only open-angle glaucoma, angle closure glaucomas were important in our setting since PACG comprises a substantial proportion of primary glaucoma in India.[27] Since the eligibility for inclusion for PACG patients included visibility of the nasal angle, we did not face any difficulty in excising the angle before phacoemulsification. The angle structures became more clearly visualized intraoperatively after we injected viscoelastic in the angle before excision. The PACD eyes in our cohort fared better and were the group with the most drop-free eyes. We think it is likely because PACD is primarily a trabecular meshwork problem that is consequent to peripheral anterior synechiae. It may be that the distal channels are less affected.

Contrary to many reports of phacoMIGS, we routinely perform all MIGS procedures before cataract surgery, and we employed the same technique for this study. We have found it easy to do MIGS in an unopened eye through a small incision, which helps stabilize the anterior chamber. In addition, the fluidics during the phacoemulsification ensure a thorough washout of the angles of blood and pigment, which would also help the aqueous outflow.

The limitation of our study is that it lacks a control group undergoing phacoemulsification with no additional glaucoma procedure. Though cataract surgery alone is known to decrease IOP,[28] especially in PACD, the decrease reported may not be clinically significant. Carolan et al.[29] compared IOP reduction after phacoemulsification in glaucoma patients to a matched cohort of patients who did not undergo surgery. The 16169 matched pairs reported a 0.99 mm Hg reduction in the surgical group versus 0.22 mm Hg in the nonsurgical group. Regarding medication use, 5% fewer surgical patients required AGM. In contrast, studies have shown a more significant reduction in IOP and AGM dependence when phacoemulsification is combined with a MIGS procedure compared to phacoemulsification alone,[30] even in PACG eyes.[31] Given this evidence, we offered BANG to all our glaucoma patients scheduled for cataract surgery.

Conclusion

Phacoemulsification with BANG presents a promising avenue for addressing both cataracts and glaucoma in patients with these coexisting conditions. Our study demonstrates its efficacy in reducing the medication burden with a favorable safety profile. While long-term studies are required to fully understand its long-term outcomes and advantages, this innovative technique holds significant potential in treating glaucoma patients with cataracts.

Conflicts of interest:

There are no conflicts of interest.

Funding Statement

Nil.