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Original Studies

Reoperations for Complications Within 90 Days After Glaucoma Surgery

Chu, Chia-Kai MD*; Liebmann, Jeffrey M. MD*; Cioffi, George A. MD*; Blumberg, Dana M. MD, MPH*; Al-Aswad, Lama A. MD, MPH

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doi: 10.1097/IJG.0000000000001484
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Trabeculectomy and tube shunt implantation remain the most commonly performed glaucoma operations worldwide while several minimally invasive glaucoma surgeries (MIGS) have been introduced in recent years. With the expansion of surgical options for managing glaucoma, selecting the most appropriate glaucoma operation involves balancing the risks of adverse events and the benefit of intraocular pressure (IOP) reduction for an individual patient. Although lower rates of surgical complications have been reported with MIGS compared with traditional incisional surgery such as trabeculectomy and tube shunt surgery, they are generally less effective in decreasing IOP. An assessment of surgical procedures requires not only an evaluation of efficacy but also an analysis of the incidence and severity of associated complications.

Trabeculectomy with mitomycin C, tube shunt surgery, transcleral cyclophotocoagulation, and trabectome each have its own well-researched set of complications that may occur, however, the unexpected early postoperative complications requiring additional surgical intervention have not been well characterized.1–4 An unplanned return to the operating room for complications may have social, occupational, and financial consequences to the patient while also increasing the surgical cost and clinical burden for any glaucoma service, especially within the first 90 days, which is the time frame most insurance companies consider as the postoperative “global period.” Furthermore, unplanned reoperations have also been proposed as a criterion to evaluate surgical quality.5,6 In a retrospective case series, Hsia et al7 reported an overall reoperation rate of 3.9% within 90 days after resident-performed glaucoma surgery but noted that there were no published data on the reoperation rate in attending-performed glaucoma surgeries to serve as a benchmark for comparison. This study seeks to describe the real-world rate of reoperations in the operating room for unplanned complications encountered within 90 days after glaucoma surgery at a single institution over a 2-year period.


This retrospective study was approved by the Institutional Review Board of Columbia University Medical Center. Electronic medical records on computerized patient record system were retrospectively reviewed of adult patients who had undergone glaucoma surgery performed by 1 of 4 glaucoma surgeons followed by an unplanned reoperation for postoperative complication within the first 90 days at the Edward S. Harkness Eye Institute at Columbia University Medical Center between June 1, 2005 and June 1, 2007. Glaucoma surgeries included were tube shunt placement, trabeculectomy with mitomycin C, and transcleral cyclophotocoagulation. The only MIGS procedure included in the study was trabectome. Tube shunt placement included both Baerveldt glaucoma implant (Johnson & Johnson Surgical Vision, Santa Ana, CA) or Ahmed glaucoma valve implant (New World Medical Inc, Rancho Cucamonga, CA).

In the present study, we focused on unplanned reoperations as the primary outcome measure. We defined an unplanned reoperation as any surgical complication requiring a return to the operating room including revision of the tube shunt, revision of the trabeculectomy, drainage of the choroidal effusion, and placement of a tube shunt as a result of a complication directly related to the index operation performed. Cyclophotocoagulation or surgery for further IOP lowering was not specifically considered a reoperation for surgical complications. Interventions performed at the slit lamp, such as needling procedures, laser suture lysis, and anterior chamber reformation, were also not included.

Data abstracted from medical records included patient demographics, glaucoma subtype, lens status, concurrent ocular history, previous intraocular surgeries, IOP, number of glaucoma medications, type of glaucoma surgery, time interval between reoperation, and type of surgical complication requiring reoperation. Univariate comparisons between treatment groups were made by the χ2 test. A P-value of ≤0.05 was considered statistically significant.


A total of 622 glaucoma procedures were performed on 600 eyes in 525 patients over a 2-year period from June 1, 2015 to June 30, 2017 by 4 glaucoma surgeons at a single institution. Of these, 275 (44%) were trabeculectomy with mitomycin C, 253 (41%) were the placement of a tube shunt, 33 (5%) were cyclophotocoagulation, and 61 (10%) were trabectome procedures. The total number of procedures performed over this 2-year span includes eyes that underwent multiple glaucoma-related procedures for further IOP lowering but does not include any unplanned reoperations for complications within 90 days.

There were 15 patients who required a return to the operating room in the first 90 days to address postoperative complications resulting in an overall reoperation rate of 2.4%. There were 7 patients (2.2%) who required reoperation in the trabeculectomy with mitomycin C group and 8 patients (3.1%) in the tube shunt group. The rate of reoperation for complications was similar between the tube group and the trabeculectomy group (P=0.67, χ2 test). There were no complications requiring reoperations in 90 days for transcleral cyclophotocoagulation or trabectome.

Clinical characteristics of the 15 patients requiring reoperation are summarized in Table 1. The mean age was 70 years. The indications for the initial glaucoma surgery were: primary open-angle glaucoma (11 patients, 73%), uveitic glaucoma (2 patients, 13%), traumatic glaucoma (1 patient, 7%), and combined-mechanism glaucoma (1 patient, 7%). Six patients were pseudophakic and 7 patients had previous intraocular surgery other than cataract surgery. Seven patients had combined intraocular surgery at the time of glaucoma surgery, including 5 with concurrent cataract extraction.

Demographics and Preoperative Characteristics of Patients Who Underwent Reoperation Within 90 Days After Glaucoma Surgery

The indications for reoperation were wound leaks (5 patients), serous choroidal effusion (3 patients), bleb encapsulation (2 patients), and tube-related issues (5 patients). Specifically, 3 patients had tube exposure, 1 patient had tube retraction, and 1 patient had persistent iritis from the iris touching the tube. No subject required an anterior chamber washout for hyphema. Mean (SD) time to reoperation in the immediate postoperative period was 6.4 (3.1) weeks. The type of complication requiring reoperation on the basis of the type of surgery is summarized in Table 2. There was no aqueous misdirection, suprachoroidal hemorrhage, blebitis, or endophthalmitis within the 90-day postoperative period in our study.

Type of Complication Requiring Reoperation on the Basis of Type of Surgery


In this retrospective study, we reviewed the rates of reoperation and complication within 90 days of attending-performed tube shunt placement, trabeculectomy with mitomycin C, transcleral cyclophotocoagulation, and trabectome at the Edward S. Harkness Eye Institute at Columbia University Medical Center. Among the 622 glaucoma surgeries performed, postoperative complications requiring reoperations within 90 days developed in 15 patients resulting in an overall reoperation rate of 2.4% with a similar rate of reoperation between patients who underwent trabeculectomy with mitomycin C and tube shunt placement. This overall rate is also low and comparable with previous studies. To our knowledge, this is the first study reporting the real-world rate of unplanned return to the operating room within the 90-day postoperative period after attending-performed glaucoma surgery.

Several studies have reported on the serious complication rate after surgery requiring reoperation, including the tube versus trabeculectomy study that reported a 7% complication after tube shunt surgery and 5% after trabeculectomy in the first year of follow-up.7 A total of 8 patients in the tube group underwent reoperations including 2 for aqueous misdirection, 1 for endophthalmitis, 1 to relieve obstruction of the tube by vitreous, 1 for persistent corneal edema, 1 for drainage of a choroidal effusion, 1 for a choroidal and retinal detachment, and 1 for lysis of iris adhesion to tube. Five patients in the trabeculectomy group required additional surgery for drainage of choroidal effusion, drainage of a suprachoroidal hemorrhage, endophthalmitis, and persistent corneal edema. Although this study had a longer follow-up period of 1 year and did not look specifically at reoperations within 90 days, it found the rate of reoperation for complications over a longer time span to be similar between the tube group and trabeculectomy group.

Conversely, in the primary tube versus trabeculectomy study, the rate of reoperation for complications after 1 year of follow-up was significantly higher in the trabeculectomy with mitomycin C group compared with the tube group.8,9 A total of 7 patients (6%) in the trabeculectomy group underwent reoperations including 4 bleb revision for wound leaks, 2 patients with hypotony maculopathy, and 1 patient with an 8-ball hyphema. One patient (1%) in the tube group underwent tube removal for exposure of the endplate. Our findings also found wound leaks to be the main indication for reoperations after trabeculectomy with mitomycin C given the immediate filtration of aqueous near the limbus in comparison with a tube shunt surgery that produces delayed drainage of aqueous humor to an area remote from the limbus. By the nature of the primary tube versus trabeculectomy study, none of the eyes had previous incisional ocular surgery. Compared with our study, the higher rate of reoperations for complications in the tube group in our study may potentially be attributed to the present occurrence of previous intraocular surgeries that potentially compromises the conjunctiva and lead to increased rates of tube complications such as tube exposure.

There are several limitations to our study. It is not unexpected that retrospective case series generally report lower complication rates than prospective studies given that they may be overlooked unless attention is directed specifically towards their detection. Therefore, the actual complication rate of necessitating surgery may be higher. Similarly, patients undergoing surgical reoperation with an outside hospital provider would not have been identified by the methods of this study, however, it can be reasonably assumed that this would be a very small number of patients. Finally, the shorter follow-up period compared with previous studies may miss surgical complications such as endophthalmitis and persistent corneal edema that are not necessarily seen in the early postoperative time frame but are nonetheless serious complications.

In summary, our study was the first to report the real-world reoperation rate for trabeculectomy with mitomycin C, tube shunt, trabectome, and transcleral cyclophotocoagulation within the 90-day postoperative period. The reoperation rates are comparable between the trabeculectomy with mitomycin C and tube shunt groups, and consistent with prior published results. Common indications for reoperation within 90 days include wound leak and tube-related issues. Although a full discussion on the ways to minimize reoperation rates is beyond the scope of this paper, consideration can be given to surgeon awareness of wound closures in trabeculectomy with an antifibrotic agent. Meanwhile, given that tube shunts are commonly used when there is a higher likelihood of failure with a filtering surgery, it is not surprising that there may be tube exposure. Such information is useful not only in terms of what to expect or examine closely during postoperative visits but also in terms of discussing expected outcomes with patients. Notably, for the trabectome, there was no reported reoperation for complications which is in line with previous studies regarding the overall safety of MIGS procedures. To the best of our knowledge, published data on 3-month reoperation rates secondary to complications after glaucoma surgery are limited.


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9. Gedde SJ, Feuer WJ, Shi W, et al. Treatment outcomes in the primary tube versus trabeculectomy study after 1 year of follow-up. Ophthalmol. 2018;125:650–663.

glaucoma surgery; trabeculectomy; tube shunt; trabectome; MIGS; complication rate after glaucoma surgery; return to the OR in 90 days

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