Surgical outcomes of additional ab interno 240° suture trabeculotomy as a second surgery for patients with primary open-angle glaucoma

Surgical outcomes of additional ab interno 240° suture trabeculotomy as a second surgery for patients with primary open-angle glaucoma | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Surgical outcomes of additional ab interno 240° suture trabeculotomy as a second surgery for patients with primary open-angle glaucoma Hidetsugu Mori, Tatsunori Kiriishi, Masatoshi Omi, Masayuki Ohnaka, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6216755/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Trabeculectomy (TLE) is a common secondary procedure for patients with primary open-angle glaucoma (POAG) who require additional surgery after trabeculotomy (TLO). However, TLE presents substantial postoperative challenges and an increased risk of complications. We evaluated the outcomes of an additional ab interno 240° TLO using a suture in patients with POAG who had previously undergone ab externo 120° TLO with a metal probe. This retrospective study included 22 eyes from 19 patients with POAG who underwent 240° ab interno suture TLO at Kansai Medical University Hospital between January 2015 and December 2024. The parameters assessed included the interval between procedures, intraocular pressure (IOP), use of IOP-lowering medications, early complications (hyphema with niveau formation and transient IOP spikes), and surgical success (Kaplan–Meier analysis). The mean interval between surgeries was 78.1 months. At 12 months, the median IOP decreased from 18.8 mmHg to 14 mmHg. The use of IOP-lowering medications was significantly reduced for up to 3 months. Kaplan–Meier analysis showed a 50% success rate. Hyphema and transient IOP spikes occurred in 3 of 22 eyes. These findings suggest that 240° ab interno suture TLO may be a viable alternative to TLE for additional glaucoma management. Health sciences/Diseases/Eye diseases Health sciences/Signs and symptoms/Eye manifestations primary open-angle glaucoma trabeculotomy ab interno suture secondary surgery Figures Figure 1 Figure 2 Figure 3 Introduction To suppress the progression of visual field loss, reducing intraocular pressure (IOP) is the most critical factor in patients with glaucoma. Trabeculotomy (TLO) and trabeculectomy (TLE) are well-established surgical procedures for lowering IOP, as reported in previous studies [ 1 – 10 ]. TLO involves surgically cleaving the juxtacanalicular tissue of the trabecular meshwork (TM) and the inner wall of Schlemm’s canal (ISC) to eliminate resistance to aqueous outflow, thereby reducing IOP. Over the past decade, there has been a substantial shift from the ab externo to the ab interno approach in TLO procedures. Ab externo TLO for congenital and juvenile glaucoma was first described by Burian [ 1 ] and Smith [ 2 ] in the 1960s. Furthermore, Tanihara [ 3 ] et al. demonstrated that ab externo TLO using a metal probe could also be an effective treatment for other types of open-angle glaucoma. However, ab externo TLO requires an extensive conjunctival incision and the creation of a scleral flap. Since 2012, ab-interno TLO procedures that avoid conjunctival and scleral incisions have been introduced as minimally invasive glaucoma surgeries (MIGS) [ 4 ]. Ab-interno TLO, performed using the Kahook Dual Blade (KDB; New World Medical, Rancho Cucamonga, CA, USA), microhooks, or a suture (5 − 0 nylon), is also known as gonioscopy-assisted transluminal trabeculotomy (GATT). Recently, GATT has gained global popularity due to its shorter surgical duration and the relative ease of its technique compared to ab-externo TLO. For patients with primary open-angle glaucoma (POAG) who underwent TLO as their initial surgical treatment and later required additional glaucoma surgery, TLE has commonly been performed as a second procedure. Since its introduction in 1968, TLE has been regarded as the most effective surgical method for reducing IOP [ 5 ]. Given its efficacy, TLE is the preferred procedure for eyes with advanced glaucoma or when achieving very low IOP is necessary. However, TLE is a complex surgical intervention associated with postoperative management challenges and complications [ 6 ], including decreased visual acuity, blebitis/endophthalmitis, choroidal effusions, and hypotony maculopathy. Moreover, TLE requires a high level of surgical expertise to manage intraoperative and postoperative adjustments appropriately. Consequently, glaucoma surgeons aim to avoid TLE whenever possible. Nambu et al. [ 7 ], who were affiliated with our institution, reported the long-term surgical outcomes of ab-externo TLO combined with cataract surgery as the initial intervention for patients with POAG. Their results showed a success rate (IOP < 20 mmHg) of 62% at eight years. However, approximately 40% of patients with POAG had an IOP exceeding 20 mmHg eight years postoperatively, necessitating additional glaucoma surgery to further lower IOP. Despite this need, only a few reports [ 8 , 9 ] have evaluated the effectiveness of a second TLO. In this retrospective 12-month follow-up study, we investigated the surgical outcomes of additional ab-interno TLO using a suture (S-TLO; 240° incision of TM and ISC) in patients with POAG who underwent ab-externo TLO using a metal probe (M-TLO; 120° incision of TM and ISC) as their initial procedure. Results A total of 22 eyes from 19 patients (9 men and 10 women) with POAG who underwent S-TLO following M-TLO with cataract surgery were included in this study. The mean age at the time of additional S-TLO was 66.9 ± 10.8 years. The mean interval between the first M-TLO and the second S-TLO was 78.1 ± 52.4 months. IOP reduction (Fig. 1 ) Figure 1 illustrates changes in mean baseline and postoperative IOP values at each time point. The median IOP values at different time points were as follows: Baseline: 18.8 mmHg (16.9–21.3) Postoperative IOP: 1 week: 14.0 mmHg (10.8–21.5), 13.8% reduction ( p = 0.0009); 1 month: 14.0 mmHg (11.5–16.0), 26.0% reduction ( p = 0.0002); 3 months: 15.0 mmHg (13.5–17.0), 16.3% reduction ( p = 0.00176); 6 months: 14.0 mmHg (13.0–16.8), 18.3% reduction ( p = 0.003); 9 months: 14.0 mmHg (13.0–16.3), 21.4% reduction ( p = 0.0009); 12 months: 14.0 mmHg (12.5–16.5), 21.4% reduction ( p = 0.001). Postoperative IOP remained significantly lower than baseline from one week to 12 months. Number of IOP-lowering medications (Fig. 2) Figure 2 illustrates changes in the mean number of IOP-lowering medications before and after surgery in patients with POAG. The mean number of medications at each time point was as follows: Baseline: 4.3 ± 0.9 Postoperative medication use: 1 week: 1.6 ± 1.4 ( p < 0.0001); 1 month: 2.7 ± 1.0 ( p < 0.0001); 3 months: 3.5 ± 1.0 ( p = 0.0453); 6 months: 3.8 ± 1.0 ( p = 0.33); 9 months: 3.8 ± 1.2 ( p = 0.3922); 12 months: 3.9 ± 0.6 ( p = 0.6266). Surgical Success Rate (Fig. 3) The Kaplan–Meier cumulative survival curve for patients with POAG is shown in Fig. 3 . The success rate of additional S-TLO was 50% at 12 months postoperatively. Postoperative Complications The incidence of early postoperative complications, including hyphema with niveau formation (> 1 mm) and transient IOP spikes (> 30 mmHg), is summarized below. Both transient IOP spikes and hyphema with niveau formation occurred in 3 of 22 eyes (13.6%) within 2 weeks after surgery. These complications resolved spontaneously within one to two weeks without requiring anterior chamber washout in any case. Discussion In this retrospective study, we evaluated the surgical outcomes of a 240° incision ab-interno S-TLO following a 120° incision ab-externo M-TLO combined with cataract surgery over a 12-month postoperative follow-up period in patients with POAG. Before the introduction of MIGS, glaucoma surgeons primarily performed TLE or, in rare cases, a second M-TLO after the initial M-TLO [ 8 ]. Over the past decade, various MIGS devices have been developed and widely adopted. Currently, after an initial M-TLO, the available options for a second glaucoma surgery include an additional M-TLO (ab-externo approach, 120° incision of the TM and ISC), S-TLO (ab-interno approach, 240° incision of the TM and ISC, as in this study), or glaucoma filtration procedures such as TLE, PreserFlo, Paul, Ahmed, and Baerveldt glaucoma implants. In clinical practice, most glaucoma surgeons prefer glaucoma filtration procedures as the second intervention after TLO. However, numerous early and late postoperative complications have been reported with glaucoma filtration procedures, including bleb leakage, choroidal detachment, suprachoroidal hemorrhage, shallow anterior chamber, bullous keratopathy, visual loss, endophthalmitis, wipe-out syndrome in advanced glaucoma, and ocular hypotony. Given these risks, both glaucoma surgeons and patients must carefully consider the challenges associated with glaucoma filtration procedures. To avoid glaucoma filtration surgeries, recent studies have investigated the efficacy of a second TLO. Otsu et al. [ 8 ] reported that the mean IOP at 12 months following a second ab-externo M-TLO (120° incision of the TM and ISC) was significantly reduced from baseline, from 20.1 mmHg to 16.3 mmHg. Similarly, Grover et al. [ 9 ] demonstrated that the mean IOP at 12 months after a second ab-interno TLO (360° incision of the TM and ISC) showed a significant reduction from baseline, from 25.7 mmHg to 16.3 mmHg. Consistently, our study also demonstrated a significant reduction in median IOP at 12 months following a second ab-interno TLO (240° incision of the TM and ISC), from 18.8 mmHg to 14.0 mmHg. These findings suggest that a second TLO can achieve postoperative IOP levels in the mid-teens. However, the reduction in the mean number of IOP-lowering medications was minimal across studies: 3.0 to 2.3 in Otsu et al. [ 8 ], 3.2 to 2.0 in Grover et al. [ 9 ], and 4.3 to 3.9 in our study. The success rate, as analyzed by Kaplan–Meier survival analysis, varied among studies: 100% in Otsu et al. [ 8 ], 80% in Grover et al. [ 9 ], and 50% in this study. The reason for the lower survival rate in this study remains unclear. However, the combination of Schlemm’s canal endothelium removal and deep sclerectomy (SER + DS) in the second M-TLO performed by Otsu et al. [ 8 ] may have contributed to their higher survival rate by providing a mild filtration effect. We previously reported 1-year outcomes of first-time TLO using a metal probe, KDB, and suture in patients with POAG [ 10 ]. The postoperative IOP (14.0 mmHg) and IOP reduction rate (21.4%) in the second S-TLO (240° incision of the TM and ISC) were slightly higher than those observed in the first M-TLO and S-TLO (postoperative IOP = 12.0 mmHg and 12.5 mmHg; IOP reduction rate = 32.4% and 32.8%, respectively). Additionally, the success rate of the second S-TLO (50%), as analyzed by Kaplan–Meier survival analysis, was slightly lower than that of the first M-TLO and S-TLO (65.7% and 58.3%, respectively). Based on our results, a second ab-interno TLO may be a viable option under specific criteria. Although TLE remains the preferred approach for severe POAG cases, an additional S-TLO may be a preferable choice for patients with early- to middle-stage glaucoma, those facing postoperative management challenges—particularly individuals with dementia—or those with reduced activities of daily living due to systemic diseases. This study has some limitations. First, the surgical devices (metal probe vs. suture) and the extent of TM and ISC incision differed between the first (M-TLO) and second (S-TLO) procedures. Second, cataract surgery performed during the first M-TLO may have contributed to IOP reduction due to anatomical changes, such as increased angle width or traction of the ciliary zonules in pseudophakic eyes. In conclusion, our findings suggest that a 240° ab-interno suture TLO as a second surgery could be a useful alternative to glaucoma filtration surgeries for patients with POAG who have undergone M-TLO as their initial procedure. Methods This retrospective study included 22 eyes from 19 patients with POAG who underwent S-TLO with a 240° incision of the TM and ISC using a 5 − 0 nylon suture. This procedure was performed following an initial M-TLO involving a 120° incision of the TM and ISC using a metal probe. Patients were treated at Kansai Medical University Hospital, Japan, between January 2015 and December 2024. The study adhered to the principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Kansai Medical University following a review of electronic medical records. All patients underwent comprehensive ophthalmic examinations, including best-corrected visual acuity assessment, slit-lamp biomicroscopy, gonioscopy, funduscopy, and IOP measurement using Goldmann applanation tonometry. POAG was diagnosed based on an IOP > 21 mmHg, with or without IOP-lowering medications, an open anterior chamber angle (Shaffer grade 3 or 4) on gonioscopy, and optic neuropathy characterized by corresponding optic disc and visual field defects. Patients were excluded if they had pre-existing or co-existing ocular diseases, a history of steroid therapy, ocular trauma, or prior ocular surgery, including laser treatment. Those with a narrow anterior chamber angle on gonioscopy or intraoperative complications were also excluded. Additionally, patients with POAG who had a follow-up period of less than 12 months were not included in the analysis. Surgical procedures At the initial M-TLO, performed via the ab externo approach in combination with cataract surgery, a 120° incision was made in the nasal or temporal-inferior region of the TM and ISC. The detailed surgical technique for M-TLO has been described in previous reports [ 7 – 10 ]. For the subsequent ab interno S-TLO, all procedures were performed under local anesthesia by experienced glaucoma specialists (first author: H.M). Using a Swan-Jacob gonioprism, a Mori Upright Surgical Gonio Lens (Ocular Instruments, Bellevue, WA, USA), and/or an Ocular Ahmed 1.5× Surgical Gonio Lens (Ocular Instruments, Bellevue, WA, USA), an approximately 1–1.5 mm incision was made in the TM through a corneal side port at the 12 o’clock position using a 20-gauge V-lance. A 5 − 0 nylon suture (Mani Nylon, Mani, Tochigi, Japan) was inserted into Schlemm’s canal through the TM and advanced circumferentially along the ISC using 23-gauge disposable microsurgical forceps (DSP forceps, Alcon, Tokyo, Japan). Once the suture tip reached the prior incision site from the initial trabeculotomy, it was retrieved from the contralateral edge of the previous incision, completing a 240° incision of the TM and ISC. Postoperative Management All patients received standardized postoperative topical medications, including 1.5% levofloxacin and 0.1% betamethasone phosphate for 4 weeks. IOP-lowering medications were discontinued postoperatively but were reintroduced if IOP exceeded baseline values. Parameters evaluated The following parameters were assessed: Demographics : Sex, age, and time interval between the initial M-TLO and subsequent S-TLO. IOP : Preoperative and postoperative IOP at 12 months, as well as the percentage reduction from baseline. IOP-Lowering Medications : Number of medications required preoperatively and at follow-up intervals. Postoperative Complications : Incidence of early complications (within one month). Baseline IOP was defined as the mean of the three most recent measurements before S-TLO. The most common early postoperative complications were: Hyphema : Blood accumulation in the anterior chamber exceeding 1 mm in height, detected via slit-lamp biomicroscopy. IOP Spike : Transient elevation of IOP > 30 mmHg. Postoperative IOP and the number of IOP-lowering medications were recorded at 1 week and at 1, 3, 6, 9, and 12 months after surgery. Statistical analyses All statistical analyses were performed using JMP software version 17 (SAS Inc., Cary, NC, USA). Data are presented as the mean ± standard deviation for normally distributed variables and as the median and interquartile range for non-normally distributed variables. Dunn’s multiple comparison test was used to compare preoperative and postoperative IOP values, while Dunnett’s test was applied to analyze changes in the number of IOP-lowering medications from baseline. If a combination of IOP-lowering medications was used, it was counted as two drugs. Kaplan–Meier survival analysis was conducted to estimate the cumulative probability of surgical success, and the log-rank test was used to compare S-TLO procedures. Surgical failure was defined as: A reduction of 21 mmHg or < 5 mmHg on two consecutive visits, and requirement for additional glaucoma surgery at least one month after the initial procedure. A p- value < 0.05 was considered statistically significant. Abbreviations trabeculotomy: TLO; trabeculectomy: TLE; intraocular pressure: IOP; trabecular meshwork: TM; inner walls of Schlemm’s canal: ISC; minimally invasive glaucoma surgery: MIGS; primary open-angle glaucoma: POAG Declarations Ethics Approval and Informed Consent This study was conducted in accordance with the Declaration of Helsinki and was approved by the Institutional Review Board of Kansai Medical University (Approval Number: 2023270, July 5, 2024). Informed consent was obtained from all patients before inclusion in the study. Ethical approval was granted following a review of electronic medical records by the Institutional Review Board of Kansai Medical University. Data Availability All data generated or analyzed during this study are included in this published article. The data that support the findings of this study are available from the corresponding author, [H.M:Hidetsugu Mori], upon reasonable request. Author Contributions: The research was designed by H.M. and H.I. Data analysis was performed by H.M. Surgeries were conducted by H.M. The manuscript was written by H.M. with support from T.K., M.O. (Masatoshi Omi), M.O. (Masayuki Ohnaka), and H.I. All authors have read and approved the final version of the manuscript. Additional Information Competing Interests: The authors declare no competing interest. Funding: This research received no external funding. References Burian, H. M. A case of Marfan’s syndrome with bilateral glaucoma. With the description of a new type of operation for developmental glaucoma (trabeculotomy ab externo). Am . J . Ophthalmol. 50 , 1187–1192 (1960). Smith, R. A new technique for opening the canal of Schlemm. Preliminary report. Preliminary report. Br . J . Ophthalmol. 44 , 370–373 (1960). Tanihara, H., Negi, A., Akimoto, M. et al . Surgical effects of trabeculotomy ab externo on adult eyes with primary open angle glaucoma and pseudoexfoliation syndrome. Arch Oph- thalmol 111 , 1653–1661 (1993). Saheb, H. & Ahmed, I. I. Micro-invasive glaucoma surgery: Current perspectives and future directions. Curr. Opin. Ophthalmol. 23 , 96–104 (2012). Cairns, J. E. Trabecylectomy. Preliminary report of a new method. Am. J. Ophthalmol . 66 , 673-679 (1968). Lim, R. The surgical management of glaucoma: A review. Clin. Exp. Ophthalmol. 50 , 213-231 (2022). PMID 35037376. Nambu, H. et al . Long-term surgical results of initial trabeculotomy combined with sinusotomy performed inferiorly. Nippon Ganka Gakkai Zasshi 116 , 740–750 (2012). Otsu, Y. et al . Reduction of intraocular pressure by Additional trabeculotomy Ab Externo in Eyes with Primary Open-angle Glaucoma. J. Glaucoma 27 , 914-919 (2018). PMID 29916998. Grover, D. S. et al . Gonioscopy-assisted transluminal trabeculotomy, ab interno trabeculotomy: Technique report and preliminary results. Ophthalmology 121 , 855-861 (2014). PMID 24412282. Mori, H., Kiriishi, T., Omi, M., Ohnaka, M. & Imai, H. One-year outcomes of trabeculotomy with 120 ◦ , 180 ◦ , or 360◦ Schlemm’s canal incision for primary open-angle glaucoma: A retrospective study. J. Clin. Med . 13 , 7653 (2024). PMID 39768576. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 19 Aug, 2025 Reviews received at journal 17 Aug, 2025 Reviewers agreed at journal 25 Jul, 2025 Reviews received at journal 25 Jul, 2025 Reviewers agreed at journal 16 Jul, 2025 Reviewers invited by journal 02 Jul, 2025 Editor assigned by journal 01 Jul, 2025 Editor invited by journal 25 Mar, 2025 Submission checks completed at journal 24 Mar, 2025 First submitted to journal 13 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6216755","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":480072456,"identity":"2ed72e3d-2435-4729-b859-2403accaa8ea","order_by":0,"name":"Hidetsugu Mori","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYJCCwwwVB3gYGNjAHAOoIBsBLWegWg4Qq4WZse0AA7oW3EC3vffh4cJ5d2TM248lfv5Qw2CsOyOB8cMPBr48XFrMzhw3ODxz2zMemTNphyUOHGMwM7uRwCzZw8BWjFPLjTSGw7zbDvNIMKQ3SBxgY7ABamGQBjozsQGvljlALfzPm38c+AfWwvybsJYGoBaJtGMSB9vADmPDb8uZYwyHeY6BtDxLszjbJ2FsduZhm2WPAR6/HG9j/sxTc9hegj/N+EbFNxvDbceTD9/4UXEMZ4ihAwkgZgQ6yeBYArFa4KCGdC2jYBSMglEwXAEAW7pYx9PwnNQAAAAASUVORK5CYII=","orcid":"","institution":"Kansai Medical University","correspondingAuthor":true,"prefix":"","firstName":"Hidetsugu","middleName":"","lastName":"Mori","suffix":""},{"id":480072457,"identity":"88f46485-fb3e-4fea-a00d-4de31f89e22c","order_by":1,"name":"Tatsunori Kiriishi","email":"","orcid":"","institution":"Kansai Medical University","correspondingAuthor":false,"prefix":"","firstName":"Tatsunori","middleName":"","lastName":"Kiriishi","suffix":""},{"id":480072458,"identity":"6d99bdb8-f123-430d-8f59-78e103d6e5d3","order_by":2,"name":"Masatoshi Omi","email":"","orcid":"","institution":"Kansai Medical University","correspondingAuthor":false,"prefix":"","firstName":"Masatoshi","middleName":"","lastName":"Omi","suffix":""},{"id":480072459,"identity":"ef5a6487-c14a-4679-8d38-5a8bb6665fc7","order_by":3,"name":"Masayuki Ohnaka","email":"","orcid":"","institution":"Kansai Medical University","correspondingAuthor":false,"prefix":"","firstName":"Masayuki","middleName":"","lastName":"Ohnaka","suffix":""},{"id":480072460,"identity":"f6c2891f-87a9-4f64-bdf0-cf888d06252c","order_by":4,"name":"Hisanori Imai","email":"","orcid":"","institution":"Kansai Medical University","correspondingAuthor":false,"prefix":"","firstName":"Hisanori","middleName":"","lastName":"Imai","suffix":""}],"badges":[],"createdAt":"2025-03-13 05:53:46","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6216755/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6216755/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86138039,"identity":"294ce3ed-46fd-4f94-9f0e-ad3d39538d27","added_by":"auto","created_at":"2025-07-07 08:08:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":185955,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTime course of IOP in patients with POAG receiving 2\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003end\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e S-LOT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The median intraocular pressure (IOP) was significantly reduced postoperatively compared with baseline (p \u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6216755/v1/adc130ba0db7ec2c8befcc82.png"},{"id":86138035,"identity":"30f84151-d085-4522-9da1-13062ce71f8d","added_by":"auto","created_at":"2025-07-07 08:08:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":173431,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTime course of changes in the number of IOP-lowering medications in\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003epatients with POAG receiving 2\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003end\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e S-TLO\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The number of intraocular pressure (IOP)-lowering medications was significantly reduced from baseline to the 1-month follow-up in patients with primary open-angle glaucoma (POAG) (p \u0026lt; 0.05)\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6216755/v1/69e502ff1767b81548f19ea2.png"},{"id":86138037,"identity":"1a2adf52-08b9-4fe5-aa9e-58c852de526f","added_by":"auto","created_at":"2025-07-07 08:08:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":103968,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKaplan–Meier survival curves for patients treated with 2\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003end\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e S-LOT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Patients with primary open-angle glaucoma (POAG) treated with a second suture trabeculotomy (S-TLO) showed a 50% success rate at 12 months postoperatively.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6216755/v1/dda9a4e41509303bb9b45d75.png"},{"id":86139355,"identity":"179491fc-0a73-4031-80ef-67177f10dcde","added_by":"auto","created_at":"2025-07-07 08:16:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1072680,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6216755/v1/97bd8efd-929c-4f66-a4f4-e28d4ef33c4f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Surgical outcomes of additional ab interno 240° suture trabeculotomy as a second surgery for patients with primary open-angle glaucoma","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTo suppress the progression of visual field loss, reducing intraocular pressure (IOP) is the most critical factor in patients with glaucoma. Trabeculotomy (TLO) and trabeculectomy (TLE) are well-established surgical procedures for lowering IOP, as reported in previous studies [\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5 CR6 CR7 CR8 CR9\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. TLO involves surgically cleaving the juxtacanalicular tissue of the trabecular meshwork (TM) and the inner wall of Schlemm\u0026rsquo;s canal (ISC) to eliminate resistance to aqueous outflow, thereby reducing IOP. Over the past decade, there has been a substantial shift from the ab externo to the ab interno approach in TLO procedures. Ab externo TLO for congenital and juvenile glaucoma was first described by Burian [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] and Smith [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] in the 1960s. Furthermore, Tanihara [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] et al. demonstrated that ab externo TLO using a metal probe could also be an effective treatment for other types of open-angle glaucoma. However, ab externo TLO requires an extensive conjunctival incision and the creation of a scleral flap.\u003c/p\u003e \u003cp\u003eSince 2012, ab-interno TLO procedures that avoid conjunctival and scleral incisions have been introduced as minimally invasive glaucoma surgeries (MIGS) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Ab-interno TLO, performed using the Kahook Dual Blade (KDB; New World Medical, Rancho Cucamonga, CA, USA), microhooks, or a suture (5\u0026thinsp;\u0026minus;\u0026thinsp;0 nylon), is also known as gonioscopy-assisted transluminal trabeculotomy (GATT). Recently, GATT has gained global popularity due to its shorter surgical duration and the relative ease of its technique compared to ab-externo TLO.\u003c/p\u003e \u003cp\u003eFor patients with primary open-angle glaucoma (POAG) who underwent TLO as their initial surgical treatment and later required additional glaucoma surgery, TLE has commonly been performed as a second procedure. Since its introduction in 1968, TLE has been regarded as the most effective surgical method for reducing IOP [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Given its efficacy, TLE is the preferred procedure for eyes with advanced glaucoma or when achieving very low IOP is necessary. However, TLE is a complex surgical intervention associated with postoperative management challenges and complications [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], including decreased visual acuity, blebitis/endophthalmitis, choroidal effusions, and hypotony maculopathy. Moreover, TLE requires a high level of surgical expertise to manage intraoperative and postoperative adjustments appropriately. Consequently, glaucoma surgeons aim to avoid TLE whenever possible. Nambu et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], who were affiliated with our institution, reported the long-term surgical outcomes of ab-externo TLO combined with cataract surgery as the initial intervention for patients with POAG. Their results showed a success rate (IOP\u0026thinsp;\u0026lt;\u0026thinsp;20 mmHg) of 62% at eight years. However, approximately 40% of patients with POAG had an IOP exceeding 20 mmHg eight years postoperatively, necessitating additional glaucoma surgery to further lower IOP. Despite this need, only a few reports [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] have evaluated the effectiveness of a second TLO.\u003c/p\u003e \u003cp\u003eIn this retrospective 12-month follow-up study, we investigated the surgical outcomes of additional ab-interno TLO using a suture (S-TLO; 240\u0026deg; incision of TM and ISC) in patients with POAG who underwent ab-externo TLO using a metal probe (M-TLO; 120\u0026deg; incision of TM and ISC) as their initial procedure.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 22 eyes from 19 patients (9 men and 10 women) with POAG who underwent S-TLO following M-TLO with cataract surgery were included in this study. The mean age at the time of additional S-TLO was 66.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.8 years. The mean interval between the first M-TLO and the second S-TLO was 78.1\u0026thinsp;\u0026plusmn;\u0026thinsp;52.4 months.\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eIOP reduction (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e illustrates changes in mean baseline and postoperative IOP values at each time point. The median IOP values at different time points were as follows:\u003c/p\u003e\n \u003cp\u003eBaseline: 18.8 mmHg (16.9\u0026ndash;21.3)\u003c/p\u003e\n \u003cp\u003ePostoperative IOP: 1 week: 14.0 mmHg (10.8\u0026ndash;21.5), 13.8% reduction (\u003cem\u003ep\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.0009); 1 month: 14.0 mmHg (11.5\u0026ndash;16.0), 26.0% reduction (\u003cem\u003ep\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.0002); 3 months: 15.0 mmHg (13.5\u0026ndash;17.0), 16.3% reduction (\u003cem\u003ep\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.00176); 6 months: 14.0 mmHg (13.0\u0026ndash;16.8), 18.3% reduction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003); 9 months: 14.0 mmHg (13.0\u0026ndash;16.3), 21.4% reduction (\u003cem\u003ep\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.0009); 12 months: 14.0 mmHg (12.5\u0026ndash;16.5), 21.4% reduction (\u003cem\u003ep\u0026thinsp;=\u003c/em\u003e\u0026thinsp;0.001).\u003c/p\u003e\n \u003cp\u003ePostoperative IOP remained significantly lower than baseline from one week to 12 months.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eNumber of IOP-lowering medications (Fig. 2)\u003c/h3\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e illustrates changes in the mean number of IOP-lowering medications before and after surgery in patients with POAG. The mean number of medications at each time point was as follows:\u003c/p\u003e\n\u003cp\u003eBaseline: 4.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e\n\u003cp\u003ePostoperative medication use: 1 week: 1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001); 1 month: 2.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001); 3 months: 3.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0453); 6 months: 3.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.33); 9 months: 3.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.3922); 12 months: 3.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.6266).\u003c/p\u003e\n\u003ch3\u003eSurgical Success Rate (Fig. 3)\u003c/h3\u003e\n\u003cp\u003eThe Kaplan\u0026ndash;Meier cumulative survival curve for patients with POAG is shown in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. The success rate of additional S-TLO was 50% at 12 months postoperatively.\u003c/p\u003e\n\u003ch3\u003ePostoperative Complications\u003c/h3\u003e\n\u003cp\u003eThe incidence of early postoperative complications, including hyphema with niveau formation (\u0026gt;\u0026thinsp;1 mm) and transient IOP spikes (\u0026gt;\u0026thinsp;30 mmHg), is summarized below.\u003c/p\u003e\n\u003cp\u003eBoth transient IOP spikes and hyphema with niveau formation occurred in 3 of 22 eyes (13.6%) within 2 weeks after surgery.\u003c/p\u003e\n\u003cp\u003eThese complications resolved spontaneously within one to two weeks without requiring anterior chamber washout in any case.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this retrospective study, we evaluated the surgical outcomes of a 240° incision ab-interno S-TLO following a 120° incision ab-externo M-TLO combined with cataract surgery over a 12-month postoperative follow-up period in patients with POAG.\u003c/p\u003e \u003cp\u003eBefore the introduction of MIGS, glaucoma surgeons primarily performed TLE or, in rare cases, a second M-TLO after the initial M-TLO [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Over the past decade, various MIGS devices have been developed and widely adopted. Currently, after an initial M-TLO, the available options for a second glaucoma surgery include an additional M-TLO (ab-externo approach, 120° incision of the TM and ISC), S-TLO (ab-interno approach, 240° incision of the TM and ISC, as in this study), or glaucoma filtration procedures such as TLE, PreserFlo, Paul, Ahmed, and Baerveldt glaucoma implants.\u003c/p\u003e \u003cp\u003eIn clinical practice, most glaucoma surgeons prefer glaucoma filtration procedures as the second intervention after TLO. However, numerous early and late postoperative complications have been reported with glaucoma filtration procedures, including bleb leakage, choroidal detachment, suprachoroidal hemorrhage, shallow anterior chamber, bullous keratopathy, visual loss, endophthalmitis, wipe-out syndrome in advanced glaucoma, and ocular hypotony. Given these risks, both glaucoma surgeons and patients must carefully consider the challenges associated with glaucoma filtration procedures.\u003c/p\u003e \u003cp\u003eTo avoid glaucoma filtration surgeries, recent studies have investigated the efficacy of a second TLO. Otsu et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] reported that the mean IOP at 12 months following a second ab-externo M-TLO (120° incision of the TM and ISC) was significantly reduced from baseline, from 20.1 mmHg to 16.3 mmHg. Similarly, Grover et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] demonstrated that the mean IOP at 12 months after a second ab-interno TLO (360° incision of the TM and ISC) showed a significant reduction from baseline, from 25.7 mmHg to 16.3 mmHg. Consistently, our study also demonstrated a significant reduction in median IOP at 12 months following a second ab-interno TLO (240° incision of the TM and ISC), from 18.8 mmHg to 14.0 mmHg. These findings suggest that a second TLO can achieve postoperative IOP levels in the mid-teens.\u003c/p\u003e \u003cp\u003eHowever, the reduction in the mean number of IOP-lowering medications was minimal across studies: 3.0 to 2.3 in Otsu et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], 3.2 to 2.0 in Grover et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], and 4.3 to 3.9 in our study. The success rate, as analyzed by Kaplan–Meier survival analysis, varied among studies: 100% in Otsu et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], 80% in Grover et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], and 50% in this study. The reason for the lower survival rate in this study remains unclear. However, the combination of Schlemm’s canal endothelium removal and deep sclerectomy (SER + DS) in the second M-TLO performed by Otsu et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] may have contributed to their higher survival rate by providing a mild filtration effect.\u003c/p\u003e \u003cp\u003eWe previously reported 1-year outcomes of first-time TLO using a metal probe, KDB, and suture in patients with POAG [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The postoperative IOP (14.0 mmHg) and IOP reduction rate (21.4%) in the second S-TLO (240° incision of the TM and ISC) were slightly higher than those observed in the first M-TLO and S-TLO (postoperative IOP = 12.0 mmHg and 12.5 mmHg; IOP reduction rate = 32.4% and 32.8%, respectively). Additionally, the success rate of the second S-TLO (50%), as analyzed by Kaplan–Meier survival analysis, was slightly lower than that of the first M-TLO and S-TLO (65.7% and 58.3%, respectively).\u003c/p\u003e \u003cp\u003eBased on our results, a second ab-interno TLO may be a viable option under specific criteria. Although TLE remains the preferred approach for severe POAG cases, an additional S-TLO may be a preferable choice for patients with early- to middle-stage glaucoma, those facing postoperative management challenges—particularly individuals with dementia—or those with reduced activities of daily living due to systemic diseases.\u003c/p\u003e \u003cp\u003eThis study has some limitations. First, the surgical devices (metal probe vs. suture) and the extent of TM and ISC incision differed between the first (M-TLO) and second (S-TLO) procedures. Second, cataract surgery performed during the first M-TLO may have contributed to IOP reduction due to anatomical changes, such as increased angle width or traction of the ciliary zonules in pseudophakic eyes.\u003c/p\u003e \u003cp\u003eIn conclusion, our findings suggest that a 240° ab-interno suture TLO as a second surgery could be a useful alternative to glaucoma filtration surgeries for patients with POAG who have undergone M-TLO as their initial procedure.\u003c/p\u003e "},{"header":"Methods","content":"\u003cp\u003eThis retrospective study included 22 eyes from 19 patients with POAG who underwent S-TLO with a 240° incision of the TM and ISC using a 5 − 0 nylon suture. This procedure was performed following an initial M-TLO involving a 120° incision of the TM and ISC using a metal probe. Patients were treated at Kansai Medical University Hospital, Japan, between January 2015 and December 2024. The study adhered to the principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Kansai Medical University following a review of electronic medical records. All patients underwent comprehensive ophthalmic examinations, including best-corrected visual acuity assessment, slit-lamp biomicroscopy, gonioscopy, funduscopy, and IOP measurement using Goldmann applanation tonometry. POAG was diagnosed based on an IOP \u0026gt; 21 mmHg, with or without IOP-lowering medications, an open anterior chamber angle (Shaffer grade 3 or 4) on gonioscopy, and optic neuropathy characterized by corresponding optic disc and visual field defects. Patients were excluded if they had pre-existing or co-existing ocular diseases, a history of steroid therapy, ocular trauma, or prior ocular surgery, including laser treatment. Those with a narrow anterior chamber angle on gonioscopy or intraoperative complications were also excluded. Additionally, patients with POAG who had a follow-up period of less than 12 months were not included in the analysis.\u003c/p\u003e\u003ch3\u003eSurgical procedures\u003c/h3\u003e\u003cp\u003eAt the initial M-TLO, performed via the ab externo approach in combination with cataract surgery, a 120° incision was made in the nasal or temporal-inferior region of the TM and ISC. The detailed surgical technique for M-TLO has been described in previous reports [\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e–\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. For the subsequent ab interno S-TLO, all procedures were performed under local anesthesia by experienced glaucoma specialists (first author: H.M). Using a Swan-Jacob gonioprism, a Mori Upright Surgical Gonio Lens (Ocular Instruments, Bellevue, WA, USA), and/or an Ocular Ahmed 1.5× Surgical Gonio Lens (Ocular Instruments, Bellevue, WA, USA), an approximately 1–1.5 mm incision was made in the TM through a corneal side port at the 12 o’clock position using a 20-gauge V-lance. A 5 − 0 nylon suture (Mani Nylon, Mani, Tochigi, Japan) was inserted into Schlemm’s canal through the TM and advanced circumferentially along the ISC using 23-gauge disposable microsurgical forceps (DSP forceps, Alcon, Tokyo, Japan). Once the suture tip reached the prior incision site from the initial trabeculotomy, it was retrieved from the contralateral edge of the previous incision, completing a 240° incision of the TM and ISC.\u003c/p\u003e\u003ch3\u003ePostoperative Management\u003c/h3\u003e\u003cp\u003eAll patients received standardized postoperative topical medications, including 1.5% levofloxacin and 0.1% betamethasone phosphate for 4 weeks. IOP-lowering medications were discontinued postoperatively but were reintroduced if IOP exceeded baseline values.\u003c/p\u003e\u003ch2\u003eParameters evaluated\u003c/h2\u003e\u003cp\u003eThe following parameters were assessed: \u003cb\u003eDemographics\u003c/b\u003e: Sex, age, and time interval between the initial M-TLO and subsequent S-TLO. \u003cb\u003eIOP\u003c/b\u003e: Preoperative and postoperative IOP at 12 months, as well as the percentage reduction from baseline. \u003cb\u003eIOP-Lowering Medications\u003c/b\u003e: Number of medications required preoperatively and at follow-up intervals. \u003cb\u003ePostoperative Complications\u003c/b\u003e: Incidence of early complications (within one month).\u003c/p\u003e\u003cp\u003eBaseline IOP was defined as the mean of the three most recent measurements before S-TLO. The most common early postoperative complications were: \u003cb\u003eHyphema\u003c/b\u003e: Blood accumulation in the anterior chamber exceeding 1 mm in height, detected via slit-lamp biomicroscopy. \u003cb\u003eIOP Spike\u003c/b\u003e: Transient elevation of IOP \u0026gt; 30 mmHg.\u003c/p\u003e\u003cp\u003ePostoperative IOP and the number of IOP-lowering medications were recorded at 1 week and at 1, 3, 6, 9, and 12 months after surgery.\u003c/p\u003e\u003ch2\u003eStatistical analyses\u003c/h2\u003e\u003cp\u003eAll statistical analyses were performed using JMP software version 17 (SAS Inc., Cary, NC, USA). Data are presented as the mean ± standard deviation for normally distributed variables and as the median and interquartile range for non-normally distributed variables.\u003c/p\u003e\u003cp\u003eDunn’s multiple comparison test was used to compare preoperative and postoperative IOP values, while Dunnett’s test was applied to analyze changes in the number of IOP-lowering medications from baseline. If a combination of IOP-lowering medications was used, it was counted as two drugs.\u003c/p\u003e\u003cp\u003eKaplan–Meier survival analysis was conducted to estimate the cumulative probability of surgical success, and the log-rank test was used to compare S-TLO procedures. Surgical failure was defined as: A reduction of \u0026lt; 20% in IOP from baseline, postoperative IOP \u0026gt; 21 mmHg or \u0026lt; 5 mmHg on two consecutive visits, and requirement for additional glaucoma surgery at least one month after the initial procedure. A \u003cem\u003ep-\u003c/em\u003evalue \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003etrabeculotomy: TLO; trabeculectomy: TLE; intraocular pressure: IOP; trabecular meshwork: TM; inner walls of Schlemm\u0026rsquo;s canal: ISC; minimally invasive glaucoma surgery: MIGS; primary open-angle glaucoma: POAG\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cu\u003eEthics Approval and Informed Consent\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the Declaration of Helsinki and was approved by the Institutional Review Board of Kansai Medical University (Approval Number: 2023270, July 5, 2024). Informed consent was obtained from all patients before inclusion in the study. Ethical approval was granted following a review of electronic medical records by the Institutional Review Board of Kansai Medical University.\u003cstrong\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in this published article.\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author, [H.M:Hidetsugu Mori], upon reasonable request.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u0026nbsp;\u003c/strong\u003e The research was designed by H.M. and H.I. Data analysis was performed by H.M. Surgeries were conducted by H.M. The manuscript was written by H.M. with support from T.K., M.O. (Masatoshi Omi), M.O. (Masayuki Ohnaka), and H.I. All authors have read and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests:\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u0026nbsp; \u0026nbsp;This research received no external funding.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBurian, H. M. A case of Marfan\u0026rsquo;s syndrome with bilateral glaucoma. With the description of a new type of operation for developmental glaucoma (trabeculotomy ab externo). \u003cem\u003eAm\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e J\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e Ophthalmol.\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 1187\u0026ndash;1192 (1960). \u003c/li\u003e\n\u003cli\u003eSmith, R. A new technique for opening the canal of Schlemm. Preliminary report. Preliminary report. \u003cem\u003eBr\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e J\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003cem\u003e Ophthalmol.\u003c/em\u003e \u003cstrong\u003e44\u003c/strong\u003e, 370\u0026ndash;373 (1960). \u003c/li\u003e\n\u003cli\u003eTanihara, H., Negi, A., Akimoto, M. \u003cem\u003eet al\u003c/em\u003e. Surgical effects of trabeculotomy ab externo on adult eyes with primary open angle glaucoma and pseudoexfoliation syndrome. Arch Oph- thalmol \u003cstrong\u003e111\u003c/strong\u003e, 1653\u0026ndash;1661 (1993). \u003c/li\u003e\n\u003cli\u003eSaheb, H. \u0026amp; Ahmed, I. I. Micro-invasive glaucoma surgery: Current perspectives and future directions. \u003cem\u003eCurr. Opin. Ophthalmol.\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 96\u0026ndash;104 (2012). \u003c/li\u003e\n\u003cli\u003eCairns, J. E. Trabecylectomy. Preliminary report of a new method. \u003cem\u003eAm. J. Ophthalmol\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e \u003cstrong\u003e66\u003c/strong\u003e, 673-679 (1968).\u003c/li\u003e\n\u003cli\u003eLim, R. The surgical management of glaucoma: A review. \u003cem\u003eClin. Exp. Ophthalmol.\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 213-231 (2022). PMID 35037376.\u003c/li\u003e\n\u003cli\u003eNambu, H. \u003cem\u003eet al\u003c/em\u003e. Long-term surgical results of initial trabeculotomy combined with sinusotomy performed inferiorly. \u003cem\u003eNippon Ganka Gakkai Zasshi\u003c/em\u003e \u003cstrong\u003e116\u003c/strong\u003e, 740\u0026ndash;750 (2012). \u003c/li\u003e\n\u003cli\u003eOtsu, Y. \u003cem\u003eet al\u003c/em\u003e. Reduction of intraocular pressure by Additional trabeculotomy Ab Externo in Eyes with Primary Open-angle Glaucoma. \u003cem\u003eJ. Glaucoma\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, 914-919 (2018). PMID 29916998.\u003c/li\u003e\n\u003cli\u003eGrover, D. S. \u003cem\u003eet al\u003c/em\u003e. Gonioscopy-assisted transluminal trabeculotomy, ab interno trabeculotomy: Technique report and preliminary results. \u003cem\u003eOphthalmology\u003c/em\u003e \u003cstrong\u003e121\u003c/strong\u003e, 855-861 (2014). PMID 24412282.\u003c/li\u003e\n\u003cli\u003eMori, H., Kiriishi, T., Omi, M., Ohnaka, M. \u0026amp; Imai, H. One-year outcomes of trabeculotomy with 120\u003csup\u003e◦\u003c/sup\u003e, 180\u003csup\u003e◦\u003c/sup\u003e, or 360◦ Schlemm\u0026rsquo;s canal incision for primary open-angle glaucoma: A retrospective study. \u003cem\u003eJ. Clin. Med\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 7653 (2024). PMID 39768576.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"primary open-angle glaucoma, trabeculotomy, ab interno, suture, secondary surgery","lastPublishedDoi":"10.21203/rs.3.rs-6216755/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6216755/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTrabeculectomy (TLE) is a common secondary procedure for patients with primary open-angle glaucoma (POAG) who require additional surgery after trabeculotomy (TLO). However, TLE presents substantial postoperative challenges and an increased risk of complications. We evaluated the outcomes of an additional ab interno 240\u0026deg; TLO using a suture in patients with POAG who had previously undergone ab externo 120\u0026deg; TLO with a metal probe. This retrospective study included 22 eyes from 19 patients with POAG who underwent 240\u0026deg; ab interno suture TLO at Kansai Medical University Hospital between January 2015 and December 2024. The parameters assessed included the interval between procedures, intraocular pressure (IOP), use of IOP-lowering medications, early complications (hyphema with niveau formation and transient IOP spikes), and surgical success (Kaplan\u0026ndash;Meier analysis). The mean interval between surgeries was 78.1 months. At 12 months, the median IOP decreased from 18.8 mmHg to 14 mmHg. The use of IOP-lowering medications was significantly reduced for up to 3 months. Kaplan\u0026ndash;Meier analysis showed a 50% success rate. Hyphema and transient IOP spikes occurred in 3 of 22 eyes. These findings suggest that 240\u0026deg; ab interno suture TLO may be a viable alternative to TLE for additional glaucoma management.\u003c/p\u003e","manuscriptTitle":"Surgical outcomes of additional ab interno 240° suture trabeculotomy as a second surgery for patients with primary open-angle glaucoma","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-07 08:08:02","doi":"10.21203/rs.3.rs-6216755/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-08-19T08:18:49+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-18T02:16:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"144583784650107988530742811863466013181","date":"2025-07-25T11:36:08+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-25T07:58:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"89216035653540795135409603964029563834","date":"2025-07-16T06:12:48+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-02T16:45:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-01T06:54:26+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-03-25T06:16:26+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-25T03:00:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-03-13T05:50:29+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"95b34112-f17b-4e7a-8653-cb176783605e","owner":[],"postedDate":"July 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":50979662,"name":"Health sciences/Diseases/Eye diseases"},{"id":50979663,"name":"Health sciences/Signs and symptoms/Eye manifestations"}],"tags":[],"updatedAt":"2025-10-08T10:08:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-07 08:08:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6216755","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6216755","identity":"rs-6216755","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}