Purpose
To report outcomes and complications of trabeculotomy ab interno using the Trab360 device (Trab360; Sight Sciences, Menlo Park, California, USA) in eyes with childhood glaucomas.
Design
Multicenter retrospective interventional case series.
Methods
Eyes with childhood glaucomas that underwent Trab360 with at least 3 months follow-up were evaluated. Postoperative intraocular pressure (IOP) less than or equal to 24 mm Hg with or without medications and no additional surgery defined success.
Results
Forty-six eyes of 41 patients were included. Median age at surgery was 12 months (range 1-325 months, mean 71 months); 54% prior to 20 months. A total of 48% were right eyes; 48% were male. Mean treatment was 290°. Median follow-up was 14.5 months (range 6-34 months, mean 16.2 months). Median preoperative IOP was 30 mm Hg (range 18-49 mm Hg, mean 30.9 mm Hg); median postoperative IOP was 18 mm Hg (range 5-40 mm Hg, mean 20.3 mm Hg]. Median number of preoperative glaucoma medications was 2.5 (range 0-5, mean 2.6); median number postoperatively was 1 (range 0-4, mean 1.6). Success was achieved in 67.4% (95% CI: 51.9%-80.0%) of eyes. Among 40 eyes for which Trab360 was the first glaucoma surgery, success rate was 70% (95% CI 53.3%-82.9%). Success was achieved in 81% (95% CI 57.4%-93.7%) of primary congenital glaucoma (PCG) eyes. Among 18 PCG eyes for which Trab360 was the first glaucoma surgery, success rate was 83.3% (95% CI 57.7%-95.6%). Two eyes (4.3%) suffered cyclodialysis. There were no other significant complications.
Conclusions
Trab360 success resembles literature on other angle surgeries for childhood glaucomas. Good surgical technique and caution in high-risk angles is imperative to avoid cyclodialysis. Our study is limited by the imperfections inherent in any retrospective analysis. Single-incision ab interno trabeculotomy with the Trab360 device is effective and safe for treating childhood glaucomas, especially PCG.
In 1942, Dr Otto Barkan revolutionized the treatment of children with primary congenital glaucoma when he described and reported favorable outcomes of 196 patients treated with a new procedure, which he named “goniotomy.” Since that time, multiple techniques have been described to clear the trabecular meshwork and open the canal of Schlemm to successfully treat numerous types of childhood glaucomas. Advances in technology such as fiber-optic illuminated microcatheters and the advent of “minimally invasive glaucoma surgery” (MIGS) has brought a welcome influx of new, safer tools to the childhood glaucoma surgeon’s toolbox. The Trab360 (Sight Sciences, Menlo Park, California, USA), introduced in 2015, is one such MIGS device that can be used to perform up to 360 degrees of trabeculotomy ab interno through a single corneal incision. In this study, we report outcomes and complications of trabeculotomy ab interno using this device (Trab360) in eyes with childhood glaucomas.
Methods
We report a multicenter retrospective interventional case series of eyes with a childhood glaucoma diagnosis that underwent Trab360 by 1 of 4 surgeons based at 4 separate academic medical centers with at least 3 months of follow-up. Success was defined a priori as (1) postoperative intraocular pressure (IOP) less than or equal to 24 mm Hg with or without medications and (2) no additional surgery required to control IOP and (3) no devastating or severe complications. Postoperative IOP and number of glaucoma medications required were collected from the final follow-up visit for patients that met success criteria and from the last visit prior to additional glaucoma surgery for patients considered failures. Intraoperative and postoperative complications were reviewed. Surgery was performed at each surgeon’s discretion; patients were not randomized and there are no controls for comparison. Furthermore, sufficient corneal clarity was required for the surgeon to elect an ab interno approach for the procedure. The study followed the tenets of the Declaration of Helsinki, was approved by institutional review boards of all institutions, and was carried out in compliance with the US Health Insurance Portability and Accountability Act. Informed consent was waived for this retrospective study by the institutional review boards at each participating institution.
Surgical Procedure
The Trab360 device is a single-use ophthalmic surgical instrument that can be used to cannulate the canal of Schlemm and then cut up to 360 degrees of trabecular meshwork. It consists of a stainless-steel curved needle with an internal soft 4-0 (200 μm) blue nylon filament with a 290-μm bulbous tip that can be advanced and retracted by rotating the wheel on the handle of the device. Because it is a procedural tool as opposed to a retained implant, the FDA did not require an age-specific patient trial; hence it is approved for performing trabeculotomy in any age group. At the time of writing this paper, the Trab360 has been replaced in the market by its nearly identical cousin, the OMNI (Sight Sciences, Menlo Park, California, USA). The only difference between the 2 devices is the filament: the OMNI has a hollow cannula that deploys viscoelastic on retraction, thus allowing for both visco-canaloplasty and trabeculotomy if so desired. This study focuses on trabeculotomy only.
The positioning of the surgeon and the head of the patient are critical for optimal visualization of the angle and safe surgery. The head is may be rotated 30-45° away from the surgeon and the microscope may be tilted 30-45° in the opposite direction to create an operating angle of 60-90° that facilitates direct gonioscopy. A representative video is provided as Supplemental Material (available at AJO.com ). Usually the surgeon is seated temporally and the angle approached via a clear corneal paracentesis temporally. Miotic agents may be instilled topically preoperatively or intracamerally to achieve pupillary constriction. The anterior chamber is stabilized with viscoelastic. The tip of the Trab360 is inserted across the anterior chamber to the contralateral angle. Under direct gonioscopic view, a small entry incision is made into the trabecular meshwork (TM) using the sharp tip of the device. The filament is deployed through the slit in the TM and advanced into the canal of Schlemm by rotating the wheel of the device until it stops, accounting for approximately 180°. The device is then withdrawn from the anterior chamber in a manner that tears a 180-degree trabeculotomy ( Figure 1 ). The cannula is then retracted back into the needle by rotating the wheel in the opposite direction. The device can be reinserted with the tip facing the opposite orientation to cannulate the other half of the canal and complete the remaining 180 degrees of trabeculotomy if circumferential treatment of the angle is desired ( Figures 2 and 3 ). Viscoelastic is then washed out of the anterior chamber, and reflux of blood is noted in the angle as a sign of successful trabeculotomy and often results in a transient hyphema postoperatively. The paracentesis is sutured closed in children but may be sufficiently self-sealing in adults. Placing untied sutures before removing viscoelastic is helpful in buphthalmic eyes that are prone to rapid anterior chamber shallowing. All patients were prescribed postoperative topical steroids and antibiotics as well as 1% pilocarpine or 1% atropine at the surgeon’s discretion.
Statistical Methods
Standard descriptive statistics were generated. Success proportions were calculated, with binomial confidence intervals (CI), for the sample as a whole as well as for various subgroups. Similarly, Kaplan-Meier estimates (KM) of success, mean IOP, and IOP changes were calculated with appropriate CI.
Results
Forty-six eyes of 41 patients met inclusion criteria; 22 (48%) were right eyes. Twenty-two (48%) eyes were male; 19 (46%) patients were male. Median age at surgery (by eye) was 12 months (mean 71 months) with a range of 1-325 months (27 years), and 54% of eyes were operated prior to 20 months of age ( Figure 4 ). Patients were classified into subgroups according to the World Glaucoma Association’s Classification System for Childhood Glaucomas ( Table ). Of note, 6 eyes had undergone previous glaucoma surgery (1 micropulse cyclophotocoagulation, 2 goniotomy, 3 glaucoma drainage device). Mean amount of angle treated was 290° (9.66 clock hours) as assessed by the surgeon intraoperatively and documented in the operative report. Median follow-up was 14.5 months (mean 16.2 months) with a range of 6-34 months ( Figure 5 ). Forty-three of the 46 eyes had at least 1 year of follow-up; the other 3 had 6 months of follow-up. Median preoperative IOP was 30 mm Hg (mean 30.9 mm Hg) with a range of 18-49 mm Hg ( Figure 6 ). Median postoperative IOP at the final follow-up visit for successes and at the last follow-up visit prior to additional surgery for failures was 18 mm Hg (mean 20.3 mm Hg) with a range of 5-40 mm Hg ( Figure 7 ). Median number of preoperative glaucoma medications was 2.5 (mean 2.6) with a range of 0-5 ( Figure 8 ). Median number of glaucoma medications at the final visit for successes and at the final visit prior to additional glaucoma surgery for failures was 1 (mean 1.6) with a range of 0-4 ( Figure 9 ).
| Subgroups by Diagnosis | N of Eyes (% of Total Eyes) | Success | Notes |
|---|---|---|---|
| PCG | 21 (45.5%) | 81% | |
| JOAG | 6 (13%) | 83% | |
| Glaucoma associated with a nonacquired systemic disease or syndrome | 8 (17%) | 50% | 4 Sturge-Weber syndrome (2 successes, 2 failures) 1 Stickler syndrome (success) 1 Down syndrome (success) 2 yet-unidentified syndromes (2 failures) |
| Glaucoma associated with a nonacquired ocular anomaly | 2 (4%) | 0% | 2 ectropion uveae |
| Glaucoma associated with an acquired condition | 4 (8.5%) | 50% | 3 anterior uveitis (2 success, 1 failure) 1 chronic panuveitis (failure) → hypotony due to 1-hour cyclodialysis → cleft closed with cryotherapy → Baerveldt subsequently controlled IOP |
| GFCS | 5 (11%) | 60% | 1 hypotony due to 2-hour cyclodialysis → cleft was repaired and IOP was subsequently controlled on medications |
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