Visco-circumferential-suture-trabeculotomy-synechiolysis with phacoemulsification versus phacoemulsification alone for chronic primary angle closure glaucoma

Abstract

Purpose

To assess the surgical outcomes of visco-circumferential-suture-trabeculotomy-synechiolysis (VCSTS) with phacoemulsification compared with phacoemulsification alone for the treatment of chronic primary angle closure glaucoma (PACG).

Settings

Mansoura Ophthalmic Center, Mansoura, Egypt.

Design

Retrospective double armed interventional non randomized comparative study.

Methods

A total of 88 eyes (69 patients) with uncontrolled PACG between 2016 and 2022 were subjected to VCSTS with phacoemulsification (Group 1) or phacoemulsification (PE) alone (Group 2). The follow-up period was 24 months. Success was defined as an IOP between 6 and 18 mmHg, with a reduction of at least 30% from baseline with (qualified) or without (complete) antiglaucoma medications (AGMs).

Results

The mean ± standard deviation ages of the study patients in groups 1 and 2 were 61.1±0.9 and 61.7±0.8 years (p=0.536), respectively. The means ± standard deviations of the preoperative and final postoperative IOP and AGM in groups 1 and 2 were 27.46±0.32 and 28.0±0.3 and 14.15±1.1 and 16.7±0.71 mmHg, respectively (p<0.001), and 3.18±0.07 and 3.2±0.9 and 0.47±1.1 and 1.1±1.5, respectively (p=0.035). The rates of complete success (Kaplan‒Meier) in groups 1 and 2 were 95.3% and 86.7%, respectively (p=0.153). Mild self-limited hyphema was the most common complication in Group 1, with no serious complications reported in Group 2.

Conclusions

Phacoemulsification results in a significant and sustained reduction in IOP and the need for AGMs for at least 2 years of follow-up. The addition of VCSTS to phacoemulsification provides a greater reduction in IOP and AGMs and improved surgical success without serious complications.

Introduction

Glaucoma is the second leading cause of blindness globally, with primary angle-closure glaucoma (PACG) expected to affect 34 million people by 2040 [1, 2]. Although less common than primary open-angle glaucoma (POAG), PACG causes blindness five times more frequently [3, 4]. Different mechanisms contribute to narrowing of the anterior chamber (AC) angle, such as pupillary blocks, anteriorly inserted irises, increased lens thickness, and exaggerated lens vault, leading to trabecular meshwork (TM) obstruction by the peripheral iris [5]. PACG management aims to prevent irido-trabecular contact and intraocular pressure (IOP) elevation [6]. Trabeculectomy alone or with phacoemulsification (PE) and intraocular lens (IOL) implantation has been one of the first-line surgical options for PACG. However, complications of trabeculectomy, including malignant glaucoma, persistent hypotony, and other bleb-related complications, can damage vision [7]. PE alone can be enough to control IOP in PACG by creating more space after removing the thick lens; however, many authors recommend supplementary glaucoma surgeries, such as trabeculotomy, goniotomy, gonio-synechiolysis, Kahook dual blade goniectomy, and various types of MIGS, for fear that the TM may be damaged or that the reduction in IOP may not be sufficient to prevent further glaucomatous damage [8, 9]. While some authors advise against ab interno gonioscopy-assisted transluminal trabeculotomy (GATT) in PACG due to the presence of narrow-angle and peripheral anterior synechiae (PASs), which block the visibility of the TM during surgery[10]and the cannulation of the Schlemm’s canal (SC), which is difficult or even impossible [6, 22] Ab externo approaches, such as Ab externo rigid probe trabeculotomy (ARPT) combined with synechiolysis and PE, have shown greater efficacy than PE alone in PACG treatment [11]. Since ARPT does not achieve full 360-degree trabeculotomy, polypropylene (prolene) sutures with viscoelastic injection offer an alternative, avoiding the need for an illuminated microcatheter [12, 13]. In the current study, the authors hypothesize that a combination of Visco-Circumferential-Suture-Trabeculotomy, Synechiolysis (VCSTS), and PE in PACG patients may have an added effect on the PE alone, especially in cases with more extensive angle damage. This study aimed to assess the surgical outcomes of combined VCSTS and PE compared with PE alone in chronic PACG management.

Patients and methods

This retrospective double armed interventional non randomized comparative study.

included 88 eyes from 69 patients with medically uncontrolled chronic PACG who were diagnosed and treated at Mansoura Ophthalmic Center (2016–2023). Ethical approval was obtained from the Ethical Committee of the Faculty of Medicine of Mansoura University according to the tenets of the Declaration of Helsinki, and all patients provided informed consent after providing a clear explanation of the study design, surgical procedures, and possible consequences.

A full ophthalmologic assessment after a thorough history was performed, including best corrected visual acuity (BCVA) using decimal notation, slit lamp examination, and IOP measurement by Goldmann’s applanation tonometry (the averaged measurement was taken and recorded for each eye after 3 measurements). Gonioscopy, fundus examination and Dynamic gonioscopy, to detect and record the extent of PAS, was performed via a Zeiss 4-mirror contact lens. PAS was present when the adhesion of the iris reached the mid-TM and its extent exceeded one clock hour on indentation gonioscopy. Visual field (VF) assessment was performed via SITA strategy perimetry (Humphrey, central 24 − 2 standard strategy). Retinal nerve fibre layer (RNFL) thickness and the optic nerve head were evaluated via Swept-Source optical coherence tomography (SS.OCT; Topcon, Japan). A-scan and B-Scan ultrasound were also performed The number of antiglaucoma medications (AGMs) used was recorded. Patients were included in the study if they had (1) PACG (2) a previous patent iridotomy, (3) synechial angle closure ≥ 180° that occluded the TM as confirmed by indentation gonioscopy, (4) an IOP > 21 mmHg despite maximally tolerated AGMs (5) no history of intraocular surgery other than laser iridotomy, and (6) age-related cataract in patients aged 50 years or older. PACG was defined as elevated IOP (> 21 mmHg) and synechial angle closure of a gonioscopically narrow angle with optic nerve cupping typical of glaucoma and corresponding matching visual field defects. The exclusion criteria included acute PACG, POAG, secondary glaucoma, anticoagulant use, or media opacity affecting surgery or testing.

Eyes were scheduled to undergo either “VCSTS” with phacoemulsification (Group 1: VCSTS-PE group) or phacoemulsification alone (Group 2: PE alone group). In patients suffering from bilateral PACG (19 patients), if VCSTS-PE or PE alone was performed in one eye, the other eye was assigned to the other procedure directly and included in the study. In eyes chosen to undergo VCSTS-PE, if the circumferential procedure could not be completed for any reason, the procedure was converted to combined ARPT-PE as a salvage manoeuvre to achieve segmental 180-degree trabeculotomy and were excluded from the current study (i.e., not included in the 43 eyes of group 1).

Surgical techniques

All surgeries were performed by a single surgeon (Ahmed S. Elwehidy). Group 1 underwent VCSTS-PE, following Elwehidy’s et al. surgical technique [12]. Initially, a vicryl 6/0 superior rectus suture was used to expose the field; then, a fornix-based conjunctival flap was made, and a two-layer scleral flap was used to expose the SC. The viscoelastic agent (Healon GV, Pfizer, NY) was gradually injected (using a standard 30G viscocanalostomy cannula or the Healon cannula) into the SC ostia for dilatation. A blunted 5/0 polypropylene suture tip was inserted and advanced through the SC to create a 360° trabeculotomy with synechiolysis. Finally, the scleral flap was sutured via 10/0 nylon suture. Then, the phacoemulsification procedure was done from separate superior or temporal clear corneal incision of 2–3 mm and two side port incisions at 2–3 clock hours on either side of the main wound to be followed by a standard monofocal lens implantation. Patients in Group 2 underwent standard PE.

Postoperative care

Patients received topical ofloxacin and dexamethasone (five times-a day tapered over 4 weeks), cycloplegia three times-a day for 5 days, and IOP-lowering drops if needed. Follow-ups were performed at 1 day, 1 week, and then at 1, 3, 6, 9, 12, 18, and 24 months.

Outcome measures

Primary outcomes compared total success rates between groups. The secondary outcomes included IOP reduction, AGM use, and complications. Complete success was defined as an IOP between 6 and 18 mmHg, with a ≥ 30% reduction in IOP from baseline without AGMs or further surgery. If AGMs were needed, partial success was considered.

Statistical analysis

The data were analysed via SPSS v.16.00. Quantitative variables are expressed as the means ± standard deviations (SDs), and categorical variables are expressed as numbers (n) and percentages (%). Normality was assessed with Kolmogorov–Smirnov tests. Independent t tests were used to compare normally distributed variables, whereas chi-square tests were used to analyse categorical data. Student’s t test was used to evaluate baseline vs. posttreatment values within groups. Statistical significance was set at p ≤ 0.05.

Results

Baseline characteristics

In total, the data of 88 eyes (69 patients) were analyzed. The patients’ baseline characteristics are shown in Table 1. The patients were allocated into two groups: group 1 (33 patients, 43 eyes) and group 2 (36 patients, 45 eyes). There were no significant differences in the preoperative values, including the preoperative degrees of angle PAS and cataract subtypes, between the two groups.

Table 1.

Preoperative clinical findings in the 2 studied groups

Parameter	Group 1 N = 43	Group 2 N = 45	P value
Age (years) (Mean ± SD)	61.1 ± 0.9	61.7 ± 0.8	0.536
Gender
Male  female	12 21	12 24	1.0
Eye
Right  Left	19 24	24 21	0.404
Cataract
Ns1  Ns2  Ns3  Cortical  PSC	7 10 13 7 6	7 11 14 6 7	0.996
IOP (mmHg) (Mean ± SD)	27.46 ± 0.32	28 ± 0.3	0.176
Number of AGM (Mean ± SD)	3.18 ± 0.07	3.2 ± 0.9	0.836
Extent of PAS (angle degrees) (Mean ± SD)	250 ± 5.5	251 ± 4.8	0.366
BCVA (Decimal) (Mean ± SD)	0.59 ± 0.11	0.6 ± 0.02	0.484
CD ratio (Mean ± SD)	0.6 ± 0.02	0.6 ± 0.01	0.470
HFA MD (dB) (Mean ± SD)	−11.2 ± 0.6	−11.11 ± 0.6	0.910
HFA PSD (Mean ± SD)	7.6 ± 0.4	7.6 ± 0.4	0.914

Group 1, Visco-Circumferential-Suture-Trabeculotomy + Phacoemulsification, Group 2, phacoemulsification alone

 n Number of eyes, SD Standard deviation, Ns1, Ns2, Ns3 Nuclear sclerosis grades 1, 2 and 3, PSC, posterior subcapsular cataract, IOP  Intraocular pressure, AGM Antiglaucoma medications, PAS Peripheral anterior synechiae, CD Cup-to-disc ratio, BCVA Best corrected visual acuity, log MAR  Logarithm of minimal angle of resolution, MD Mean deviation, HFA Humphrey field analyser, PSD Pattern standard deviation

* p < 0.005 was defined as statistically significant

Primary outcome measures

Table 2 shows the total success rates for both groups, with no significant difference in true success, qualified success, or failure rates (p = 0.074). The Kaplan–Meier curves revealed 24-month success rates of 95.3% (Group 1) and 86.7% (Group 2) (Fig. 1). The difference was not statistically significant (log-rank test, p = 0.153).

Table 2.

Success rates in the 2 groups

Success	Group 1 N = 43	Group 2 N = 45	P value
Complete success	36	28	0.074
Partial success	5	11
Failure	2	6
Total success %	95.3	86.7	0.153

Group 1, Visco-Circumferential-Suture-Trabeculotomy + Phacoemulsification, Group 2, Phacoemulsification alone, n Number of eyes

The log rank test (Mantel–Cox) was used

Fig. 1.

Kaplan‒Meier survival curves of the 2 study groups

Secondary outcome measures

Table 3 summarizes the postoperative clinical data. The IOP significantly decreased in both groups (p < 0.001), with Group 1 showing a significantly lower IOP than Group 2 at all-time points (p < 0.001). (Fig. 2). The mean number of AGMs also significantly declined in both groups (p < 0.001), with Group 1 requiring fewer AGMs (p = 0.035).

Table 3.

Postoperative parameters during follow-up in the 2 groups

Parameter mean ± SD	Group 1 N = 43	Group 2 N = 45	P value
IOP (mmHg)
1 week	10.56 ± 0.16	11.8 ± 0.13	< 0.001*
1 month	11.12 ± 0.15	12.7 ± 0.14	< 0.001*
3 months	11.6 ± 0.12	13.5 ± 0.13	< 0.001*
6 months	12.11 ± 0.15	14.02 ± 0.14	< 0.001*
9 months	12.35 ± 0.18	14.9 ± 0.16	< 0.001*
12 months	12.9 ± 0.2	15.8 ± 0.3	< 0.001*
18 months	13.6 ± 1.7	16.3 ± 0.71	< 0.001*
24 months	14.15 ± 1.1	16.7 ± 0.6	< 0.001*
AGM	0.47 ± 1.1	1.1 ± 1.5	0.035*
BCVA (Decimal)	0.3 ± 0.02	0.35 ± 0.02	0.123
CD ratio	0.6 ± 0.02	0.6 ± 0.1	0.461
VF MD (dB)	−10.95 ± 0.6	−10.95 ± 0.6	0.980
VF PSD (dB)	6.16 ± 0.19	7.5 ± 0.37	0.006*
PAS (angle degrees)	25.6 ± 50.0	188.4 ± 4.7	< 0.001*

Fig. 2.

IOP trends over time in the study groups

The extent of PAS was significantly lower in both groups (p < 0.001 for Group 1, p = 0.007 for Group 2) and was lower in Group 1 at 24 months (p < 0.001). The, mean deviation (MD) in the Humphrey^® field analyser 24 − 2 (HFA) showed significant improvement compared with the baseline values in groups 1 and 2 (p < 0.001 and 0.002, respectively). There was no significant difference between the groups at 24 months (p = 0.980). Pattern standard deviation (PSD) in the HFA was significantly different in both groups at the end of the follow-up period compared with the baseline values (p = 0.004 and 0.005 in groups 1 and 2, respectively), with a significantly lower final PSD in Group 1 (p = 0.006). The mean BCVA (log MAR) improved significantly in both groups (p < 0.001). Table 4 lists the postoperative complications recorded in the 2 groups, which were not significantly different between the 2 groups, except for hyphema, which occurred in almost all the eyes in group 1. Twenty-five eyes (58%) had mild hyphema that resolved within 7 days. Ten eyes (23.3%) moderately resolved within 9–12 days. Only one eye (2.33%) developed severe hyphema, which was removed surgically via AC washing.

Table 4.

Postoperative complications

	Group 1 N = 43	Group 2 N = 45	P value
1-Hyphema: Mild Moderate Severe	(37) 25 10 2	(2) 2 0 0	< 0.0001*
2-Fibrinous exudation: resolved spontaneously removed by Nd: YAG laser	(5) 3 2	(2) 2 0	0.198
3-Transient hypotony < 6 mmHg:	2	1	0.483
4-Transient IOP elevation > 20 mmHg	4	3	0.474
5-Corneal edema	2	3	0.522

Group 1, Visco-Circumferential-Suture-Trabeculotomy + Phacoemulsification, Group 2, Phacoemulsification alone

n number of eyes, IOP  intraocular pressure, chi-square test

* p < 0.005 was considered statistically significant

Discussion

This study compared the outcomes of PE as a standalone procedure to those of PE combined with VCSTS for patients with chronic PACG with cataracts and uncontrolled IOP. Both methods, PE as a standalone and PE combined with VCSTS, were effective in lowering the IOP to a statistically normal level, although adding VCSTS to PE was more advantageous, resulting in a greater reduction in IOP with no compromise of safety. The demographic characteristics of the study population emphasize facts reported for PACG, namely, the occurrence of the disease in older age groups, the predilection for the female sex [14] and the lack of laterality preference occurring equally in the right and left eyes [11]. The clinical characteristics of the study population are equally informative. The preoperative IOP, although clearly above the statistically normal values and hence definitely above the target IOPs for the study eyes, was below 30 s, highlighting the relative efficacy of the different medical AGMs in cases of PACG compared with other reports [15]. This is echoed by the mean number of AGMs in both groups being above 3, indicating the polypharmacy needed and that the study eyes were already on maximally tolerated medical therapy for elevated IOP. Perhaps the BCVA was relatively good in both study groups, yet lens removal was recommended to debulk the anterior segment and hence open the angle of the anterior chamber in PACG (paralleling recommendations from other reports) [16]. Additionally, the study participants were clearly in the older age group in whom accommodation was not an issue, and some reported poor quality of vision, despite reasonable BCVA on the chart. The VF data were equally informative. The mean value of the MD of the study eyes demonstrated that most of the study eyes had moderate to severe disease; hence, a low target IOP was needed. Additionally, the obvious generalized reduction in retinal sensitivity is comparable with the advanced stage of PACG and, to a lesser extent, with cataracts. This effect of advanced glaucoma on the VF is in accordance with published reports [17].The outcomes of both procedures in terms of total success were not significantly different from one another, although the addition of VCSTS to phacoemulsification demonstrated a slightly higher success rate. The Kaplan–Meier survival curves indicated that the total surgical success rates in group 1 (VCSTS-PE) and group 2 (PE alone) at 24 months post-surgery were 95.3% and 86.7%, respectively (p = 0.153). However, interestingly, the complete success rate was significantly higher in group 1 (VCSTS-PE) (83.7%) than in group 2 (PE alone) (62.2%) (p = 0.074). The fact that lens removal (PE) is effective as a standalone procedure emphasizes the crucial role of lens volume in the pathology of angle closure disease (crowding of the anterior segment) and the beneficial effect of lens removal on pathology. The trend of IOP in both groups over the follow-up time points revealed an initial sharp reduction, significantly less than the preoperative values, followed by a gradual slow increase over time, although it settled at a significantly lower IOP level than the preoperative value in both groups. Nevertheless, IOP was significantly lower in group 1 (VCSTS-PE) than in group 2 (PE alone) at all the postoperative follow-up time points. This trend of IOP follows other published reports [11].

While phacoemulsification may contribute to partial mechanical synechiolysis in both groups through intraoperative manipulation and fluid dynamics, this effect alone is often insufficient to restore functional aqueous outflow in cases of chronic PACG. Prior studies have demonstrated that irreversible structural damage to the TM and the inner wall of SC may persist even after the angle is opened after synechiolysis. Therefore, the greater IOP reduction observed in the VCSTS-PE group is likely due not only to PAS lysis but, more importantly, to the creation of a direct outflow pathway through 360° trabeculotomy, enabling unhindered aqueous access to SC and the distal collector channels.

The lower IOP and lower AGMs in eyes undergoing VCSTS-PE are advantages offered by the addition of the VCSTS to PE. The improvement in BCVA probably reflects the benefits of cataract extraction, and this was almost identical in both study groups. The same applies to the marginal improvement noted in the mean deviation of VF (MD) in both study groups, paralleling other reports [18]. The stability of the C/D ratio in both groups at the final follow-up is further evidence of adequate IOP control in both groups, paralleling other studies [19]. Studying the complications of the study procedures emphasized the high safety profile of both procedures, PE as a standalone procedure and when combined with VCSTS. The occurrence of hyphema is a universal complication reported for all angle procedures [11]especially circumferential procedures [6]and is likely related to blood reflux from the episcleral veins to the SC.

Fortunately, the hyphema is self-limited in most cases. The occurrence of corneal edema is a common sequela after PE [20] and is also self-limiting. To the best of the authors’ knowledge, no published research has investigated this approach or compared the outcomes of PE as a stand-alone procedure with those of PE when combined with ab externo VCSTS in chronic PACG patients with cataracts. A recent study that combined the ab interno GATT with PE in PACG reported favourable outcomes in terms of IOP, glaucoma medications, and surgical success but with some delay of postoperative visual rehabilitation due to hyphema and fibrinous reactions [21]. In the present study, there was an overall improvement in the BCVA, and although hyphema was a common complication in group 1 (PE-VCSTS), it was self-limiting in most cases. The fibrinous exudation that occurred in a few eyes resolved spontaneously (except in 2 eyes in which the Nd: YAG laser was needed). The surgeon in the current study used a controlled amount of sodium hyaluronate to limit the occurrence of hyphema.

This study has its limitations. The retrograde nature of the study design and the relatively small number of cases in both study groups represent a limitation of the study. Absence of documentation of some postoperative data e.g., anterior chamber depth (ACD), refractive outcomes, or suture-induced astigmatism constituted another limitation in this study. However, the long follow-up duration strengthens the findings and makes them more robust.

In conclusion, phacoemulsification (PE) results in a significant and sustained reduction in IOP and the need for AGMs over at least 2 years of follow-up. The addition of VCSTS to PE provides further benefits, including greater reductions in IOP and AGMs, effective lysis of PAS, direct treatment of angle pathology, and improved surgical success, without added risks or serious complications.

Abbreviations

VCSTS

Visco-Circumferential-suture-trabeculotomy-synechiolysis

PE

Phacoemulsification

PACG

Primary angle closure glaucoma

AGMs

Antiglaucoma medications

POAG

Primary open angle glaucoma

AC

Anterior chamber

TM

Trabecular meshwork

IOP

Intraocular pressure

IOL

Intraocular lens

GATT

Gonioscopy assisted transluminal trabeculotomy

PASs

Peripheral anterior synechiae

SC

Schlemm’s canal

ARPT

Ab externo rigid probe trabeculotomy

Authors’ contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Elwehidy AS, Abdelkader AM.,GabAllah NM, Elwehidy MA. Abdelfattah D. All authors commented on previous versions of the manuscript, read and approved the final manuscript.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability

Material and data are available on demand or on Mansoura university patient data base electronic system.

Declarations

Ethics approval and consent to participate

All procedures performed in the current study involving human participants were in accordance with the ethical standards and approval of the local research ethics committee of ophthalmology department as well as the"Faculty of Medicine - Mansoura University Institutional Research Review Board"(IRB registration and approval code: R.23.10.2345R1 - 2023/10) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The nature of the study was explained to all participants in simple language and an Informed consent was obtained from all individual participants included in the study. The corresponding author ensures full access to all the data in the study and takes responsibility for the reliability as well as the availability of data and materials and the precision of the data analysis. There is no prior publication by any other journal. All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Elwehidy AS, Hagras SH, Abdelkader AM., GabAllah NM, Elwehidy MA. Abdelfattah D. All authors commented on previous versions of the manuscript, read and approved the final manuscript.

Consent for publication

There is no prior publication by any other journal. 

Competing interests

The authors declare no competing interests.