Risk factors, prevention, and repair strategies for tube erosion and exposure following glaucoma drainage device surgery: a narrative review

Introduction

Background

Glaucoma drainage device (GDD) surgery, also known as aqueous shunt or tube shunt surgery, was traditionally reserved for patients with a history of unsuccessful trabeculectomy or those with secondary glaucoma at high risk for trabeculectomy failure, including neovascular, uveitic, and aphakic glaucoma. Since the Tube Versus Trabeculectomy (TVT) Study reported a higher success rate for GDD surgery than for trabeculectomy with mitomycin C over 5 years of follow-up in eyes with prior cataract and/or filtering surgery (1), GDD surgery has gained wider acceptance in glaucoma management, and is sometimes used as a primary surgical option, serving as an alternative to trabeculectomy even in patients with less refractory glaucoma (2). However, GDD surgery is associated with specific complications related to the implantation of a foreign body, including tube obstruction, erosion, and exposure.

The terms “tube erosion” and “tube exposure” are clearly different. Tube erosion refers to the gradual thinning and breakdown of the tissue covering the drainage tube. In contrast, tube exposure occurs when the tube is no longer fully covered by conjunctival or patch graft tissue, making it visible or externally accessible (Figure 1). In clinical practice, these terms are often used interchangeably, and in this article, they are used synonymously. Tube erosion and exposure are multifactorial complications associated with GDD surgery, with contributing factors such as ocular health, surgical technique, and preexisting comorbid conditions. These complications are rare after GDD surgery; however, they require prompt surgical intervention because they carry a substantial risk of endophthalmitis, a serious and vision-threatening condition (3). Recent advances in patch graft materials and surgical techniques for GDD surgery have helped reduce the incidence of tube erosion and exposure (4).

Figure 1 Photographs of the left eye of a patient following Baerveldt glaucoma implant surgery. (A) Tube erosion (arrow). (B) Tube exposure (arrow).

Rational and knowledge gap

Tube erosion and exposure following GDD surgery face several major unresolved issues and knowledge gaps. These include limited understanding of the underlying etiology, incomplete and conflicting understanding of associated risk factors, preventive strategies supported by limited high-quality comparative evidence, high treatment failure rates often necessitating multiple interventions, the absence of standardized treatment protocols, and a critical need for prospective randomized trials to address the limitations of the predominantly retrospective evidence base.

Objective

The objective of this article is to address these unresolved issues and knowledge gaps by reviewing the incidence, etiology, risk factors, preventive strategies, and treatment options for tube erosion and exposure, thereby optimizing outcomes in GDD surgery. Additionally, this review expands upon prior literature (5) by incorporating more recent evidence and providing an updated synthesis of current management strategies, including various scleral tunnel-based techniques, alternative graft materials, tube repositioning and rerouting approaches, and adjunctive medical therapies, that may reduce erosion rates and improve long-term outcomes. This article is presented in accordance with the Narrative Review reporting checklist (available at https://aes.amegroups.com/article/view/10.21037/aes-25-62/rc).

Methods

In this narrative review, relevant English-language literature on tube erosion and exposure following GDD surgery was identified and synthesized. Peer-reviewed articles reporting clinical research, meta-analyses, case series, and case reports were included. Studies published in the database from its inception up to and including August 2025 were eligible. PubMed was searched to identify articles addressing tube erosion or exposure following GDD surgery and this search was supplemented with the Semantic Scholar corpus. Both Medical Subject Headings (MeSH) and free-text terms were used. The search terms within each concept were combined using the Boolean operator OR, while different concepts were combined using AND. The search strategy included combinations of MeSH terms and free-text keywords, such as: glaucoma drainage implant(s), glaucoma drainage device, aqueous shunt, tube shunt, GDD, erosion, exposure, tube erosion, tube exposure, incidence, etiology, risk factors, prevention, preventive strategies, treatment, and repair (Table 1). Study eligibility was determined during title and abstract screening rather than by restricting publication types in the search strategy.

Incidence of tube erosion and exposure

The incidence of tube erosion following GDD surgery varies significantly and is influenced by surgical technique, follow-up duration, population differences, and patch graft material thickness and properties. Reported rates range from 0% to 16%, and the mean or median time to tube erosion ranges from 3.5 to 25 months post-surgery (1,6-13) (Table 2).

With the introduction of donor or autologous tissue to cover the tube, the rate of tube exposure has decreased from approximately 30% to <5% (3). A meta-analysis of 38 studies including 3,255 eyes reported an overall tube erosion rate of 2.0%±2.6%, with a mean monthly exposure rate of 0.09%±0.14% (8). No significant differences were identified in exposure incidence or monthly exposure rates among different drainage devices. Large randomized controlled trials (RCTs), including the TVT Study, the Ahmed Baerveldt Comparison (ABC) Study, and the Ahmed Versus Baerveldt (AVB) Study, reported tube erosion rates of 1% to 5% over 5 years of follow-up (1,11,14). Recently, several studies have reported the use of scleral tunnel techniques, with or without patch grafts, to further reduce the incidence of tube erosion, and some studies achieved rates approaching zero (6,13).

Etiology of tube erosion and exposure

The mechanisms underlying tube exposure are unclear. Early tube exposure, occurring within the first few months post-surgery, is often attributed to surgical wound dehiscence and heightened immune responses that can lead to rapid degradation of the overlying ocular tissues (15,16). In contrast, late tube exposure, which develops months or even years after surgery, is primarily considered to result from two main mechanisms:

• A chronic low-grade immune response may cause progressive thinning of the overlying tissues (5,17). Persistent inflammation can promote collagen degradation and conjunctival melting. Furthermore, patch graft materials, such as donor sclera, pericardium, or dura mater, may undergo gradual resorption or mechanical breakdown, reducing their long-term protective effect over the tube (18).
• Mechanical factors may contribute, including increased conjunctival tension over the tube, eyelid rubbing, and tube mobility, which can create friction between the tube and surrounding tissues (4). Improper tube positioning, inadequate scleral fixation, or insufficient patch graft coverage can increase contact between the tube and the adjacent conjunctiva or patch graft. Furthermore, postoperative eye movements may exacerbate repeated friction and tissue breakdown (19).

Notably, several case reports and observational studies have noted that tubes without secure fixation can exhibit “micro-movements” during ocular pulsation and blinking, due to tube elasticity and its tendency to spontaneously return to a straight configuration over time (13,20,21). In contrast, studies using scleral tunnel techniques have reported few or no cases of tube erosion (6,13,22-24). These techniques minimize tube movement and are associated with fewer tube exposures, even in the presence of other risk factors, such as younger age, ocular inflammation, or previous surgery. These findings indicate that dynamic micro-movements of the tube play a pivotal role in the development of tube erosion, particularly when stabilization is inadequate.

Nevertheless, the relative contributions of inflammation and mechanical factors, including tube micro-movement and eyelid-related friction, remain poorly quantified. Mechanistic investigations that integrate clinical presentations with pathology, biomechanics, and wound-healing biology are required to elucidate the mechanisms underlying tube erosion and exposure.

Risk factors for tube erosion and exposure

Patient-related risk factors (Table 3)

Prior ocular surgery

Repeated ocular surgeries compromise conjunctival integrity, reduce tissue viability at the surgical site, and exacerbate scar tissue formation, predisposing patients to tube erosion. Byun et al. (30) conducted a retrospective review of Ahmed glaucoma valve (AGV) implantation and discovered that patients who had undergone one or more ocular surgeries had a higher incidence of tube exposure than those without previous ocular surgery [odds ratio (OR) =9.056; P=0.047]. Jomar et al. (28) conducted a retrospective case-control study of 136 children (21 with tube exposure and 115 without) and reported an association between multiple prior ocular surgeries and tube exposure. Prior trabeculectomy has also been identified as a risk factor for tube erosion, likely because exposure to antifibrotic agents, such as mitomycin C can increase conjunctival fragility (5). In contrast, Levinson et al. (31) did not identify prior GDD implantation as an independent risk factor for tube exposure. In their large retrospective series of 763 cases (702 primary and 61 secondary implants), secondary GDD implantation was associated with a higher incidence of tube exposure than primary implantation (13.1% vs. 5.8%); however, no significant risk was found to be associated with prior GDD.

Ocular surface conditions

Tube erosion may be more prevalent in patients with compromised conjunctival tissue due to ocular surface conditions, including preexisting and postoperative ocular inflammation. Chaku et al. (25) identified postoperative ocular inflammation as a significant risk factor for tube erosion (OR =15.180; P=0.004) in a retrospective case-control study of 32 eyes in 32 patients who required surgical revision for tube erosion. They also reported that steroid use was significantly more frequent in eyes with tube exposure than in control eyes (78.1% vs. 12.5%; P<0.0001). Geffen et al. (15) reported that ocular inflammation and surface diseases were not risk factors of conjunctival complications; however, a higher number of topical glaucoma medications was associated with an increased risk. Long-term use of multiple intraocular pressure (IOP)-lowering medications can alter conjunctival tissue and may lead to conjunctival complications (15,32). Trubnik et al. (33) discovered that dry eye syndrome was more common in eyes with tube erosion than in those without erosion, although this association was not statistically significant.

Glaucoma type

Koval et al. (27) conducted a retrospective matched case-control study and found that neovascular glaucoma (NVG) was associated with a significantly higher risk of tube erosion (OR =28.5; P=0.0064). In their cohort, diabetes mellitus was the most common cause of NVG, and a large proportion of these patients also had diabetic retinopathy. The increased risk of tube erosion in patients with NVG can be attributed to a combination of severe ocular ischemia, vascular endothelial growth factor (VEGF)-driven abnormal neovascularization, chronic inflammation, impaired wound healing (exacerbated by anti-VEGF therapy), and pre-existing conjunctival scarring and fragility associated with previous ocular interventions. Zhou et al. (34) retrospectively analyzed 306 eyes from 277 patients who underwent AGV implantation and reported that uveitic glaucoma significantly increased the risk of tube erosion. They attributed this increased risk to chronic ocular inflammation, which may induce pathological changes in the conjunctival epithelium and reduce goblet cell density. In a retrospective comparative case series, Trubnik et al. (33) reported a nonsignificant trend toward increased tube erosion in pseudoexfoliation, possibly due to underlying tissue vulnerability.

Diabetes mellitus

Diabetes mellitus can cause conjunctival vascular changes similar to those observed in the retina, suggesting impaired conjunctival perfusion, which may reduce tissue remodeling and reduce tissue strength (35). However, evidence regarding diabetes mellitus remains inconsistent, with one case-control study suggesting a protective effect and another identifying it as a major risk factor. Edo et al. (12) reported that, among patients with diabetes, implantation of the Baerveldt Glaucoma Implant (BGI) 102–350 was associated with significantly higher odds of BGI exposure compared with BGI 101–350 and BGI 103–250. The authors hypothesized that diabetes-related impairment of conjunctival blood flow may reduce tissue integrity, predisposing the patient to exposure. The presence of a Hoffman elbow in the BGI 102–350 may further increase susceptibility to exposure (OR =15.36, P=0.0389). In contrast, Chaku et al. (25) reported a lower prevalence of diabetes mellitus among patients with tube exposure compared with those without exposure (12.5% vs. 37.5%, P=0.041), while Muir et al. (10) and Byun et al. (30) found no statistically significant association between diabetes and the risk of tube exposure. This discrepancy may be partially explained by the interaction between diabetes and specific device models; diabetes substantially increased the risk of exposure, specifically when using the BGI 102–350 model, suggesting that impaired wound healing and device-specific factors may create an increased risk.

Other patient demographics

Most studies have found no significant association between tube erosion and age, sex, or ethnicity/race. However, some studies have identified specific demographic factors as potential risk factors, including age, female sex, and specific ethnic or racial backgrounds, such as Hispanic, East Asian, and White race (10,25-29).

Muir et al. (10) reported that female sex was associated with a higher risk of tube exposure [P=0.013; OR =2.004; 95% confidence interval (CI): 1.170–3.431], possibly related to a smaller average orbital volume than male patients. They also found that the White race was associated with a higher risk of exposure than the Black race (P=0.046; OR =1.693; 95% CI: 1.011–2.833). Edo et al. (12) speculated that the higher incidence of tube erosion in East Asian patients may be due to increased friction between the GDD and ocular tissues, potentially related to a narrower average palpebral fissure, tighter orbits, and a higher prevalence of dry eye disease. In addition, Koval et al. (27) found that Hispanic patients experienced a higher incidence of tube exposure than non-Hispanic patients, which was presumably linked to socioeconomic factors. Evidence regarding age as a risk factor remains inconclusive, with some studies suggesting younger age (25,28) and others suggesting older age (26), likely reflecting differences in populations and mechanisms. The mechanisms underlying the association between age and tube erosion risk are likely multifactorial. In younger patients, an increased risk may involve heightened inflammatory responses or differences in tissue healing dynamics, although the precise mechanism remains unclear. In contrast, in older patients, age likely functions as a surrogate marker for cumulative biological tissue vulnerability, including conjunctival thinning, impaired wound healing, and compromised extracellular matrix remodeling, rather than an independent causal factor. Notably, tube exposure rates have been reported to be higher in pediatric patients, likely due to frequent eye rubbing, smaller orbital volume leading to increased device mobility, prior ocular surgery, and coexisting inflammation (20,28).

Surgery-related risk factors (Table 4)

Types of GDD

The specific type of GDD has not been identified as an independent risk factor for tube erosion.

The ABC and AVB studies reported slightly higher but non-significant rates of tube erosion in the AGV group (3–4%) than in the BGI group (1–2%) (11,14). Stewart et al. (8) reported tube exposure in 37 of 1,419 eyes (2.7%) with AGV implantation, 8 of 759 eyes (1.1%) with BGI, and 19 of 1,077 eyes (1.7%) with the Molteno implant, with no significant differences among devices. They further revealed no differences based on BGI size (250, 350, or 500 mm²), the number of plates in Molteno single versus double models, or device composition in Ahmed silicone versus polypropylene models. In addition, a pooled analysis by Wang et al. (37) reported an OR of 0.66 (95% CI: 0.09–5.18) for tube exposure with AGV compared with BGI, indicating no statistically significant difference between device types.

The Paul Glaucoma Implant (PGI) has smaller external and internal tube diameters (467 and 127 µm, respectively) than the AGV (635 and 305 µm), hypothetically reducing tube erosion risk (38). Recent studies have reported tube erosion rates of 0% to 4.1% following PGI implantation with bovine pericardial patch coverage (39,40). However, Prinz et al. (36) found no significant difference in tube erosion rates between AGV (6.3%) and PGI (5.8%) when both devices were covered with fascia lata or corneal stromal patches. Research is currently ongoing to determine whether the smaller tube diameter of the PGI implantation is more effective in preventing tube erosion (17).

Tube shunt locations

Placement of the tube shunt in the inferior quadrant has been associated with a higher risk of tube exposure than placement in the superior quadrant. Levinson et al. (31) reported that implant location was a marginally significant risk factor for exposure, with rates of 12.8% and 5.4% for inferior and superior quadrant placements, respectively (P=0.056). Among primary implants, the highest exposure rate was observed in the inferonasal quadrant (17.2%). The higher incidence of tube erosion with inferior placement may be attributed to thinner conjunctiva, shallower fornices, and greater mechanical stress from eyelid movement. Conversely, superior placement benefits from a thicker conjunctiva and Tenon’s capsule and partial coverage by the upper eyelid, which may reduce the risk of tube erosion.

Patch graft materials

Patch grafts are routinely used to reduce tube erosion risk after GDD surgery. Commonly used materials include donor human sclera, pericardium, and split-thickness corneal grafts.

A meta-analysis by Stewart et al., along with several earlier studies, suggested no significant association between patch graft material and tube erosion risk (8,10,27). In contrast, Levinson et al. (31) reported the highest exposure rates in eyes covered with corneal grafts (9.2%) and pericardium (7.9%), while scleral patch grafts were associated with the lowest exposure rate (0.5%). The authors proposed that the higher exposure rate observed with corneal patch grafts might reflect their more frequent use in inferior GDD placements. Notably, superior GDDs covered with corneal patch grafts had a comparable tube exposure rate with that of primary implants. Furthermore, they noted that cases in which pericardial patch grafts were used had a longer average follow-up period, which may have contributed to the increased risk of tube exposure.

Tube erosion rates with corneal patch grafts vary by tissue processing method. Corneal patch grafts include partial-thickness, glycerol-preserved, and electron-beam-irradiated corneal tissues and offer favorable cosmetic outcomes. Partial-thickness corneal grafts have been associated with a graft melting rate of 6.7% and a tube exposure rate of 2.2%, while gamma-irradiated corneal tissue has a lower tube erosion rate of 2% (41). In addition, Wigton et al. (9) demonstrated that glycerol-preserved corneal patch grafts were associated with an even lower erosion rate of 1.9%. In the same study, pericardium patch grafts exhibited a higher erosion rate of 8.9% (P=0.0125). The median time to exposure was 252 days and 440 days for pericardium and glycerol-preserved corneal patch grafts, respectively (P=0.0017). Lankaranian et al. (7) assessed the use of human pericardium in GDD surgery by comparing 31 eyes treated with single-thickness pericardium with 59 eyes treated with double-thickness pericardium, both augmented with mitomycin C. Tube erosion occurred in 16% of eyes in the single-thickness group over a mean follow-up of 21.1 months, while no tube erosion was observed in the double-thickness group over a mean follow-up of 18.6 months (P=0.002).

The available evidence is limited by the predominance of retrospective designs. However, key determinants of tube erosion risk appear to include the thickness and processing methods of patch graft materials, surgical technique, and follow-up duration, rather than material type alone. Double-thickness preparations and scleral tunnel techniques consistently yield better outcomes than thin, avascular grafts. Surgeons should consider using double-thickness pericardium if pericardial grafts are preferred, and recognize that glycerol-preserved corneal patch grafts may offer durability advantages over pericardium.

Synthetic materials, including the collagen matrix Ologen and the permanent scleral reinforcement matrix CorNeat EverPatch, are being investigated as alternatives to human donor tissues. Ologen is a porcine-derived, biodegradable collagen matrix originally designed for use with trabeculectomy. Stephens et al. (42) reported that Ologen provided comparable short-term efficacy as a patch graft for GDD surgery, with a mean follow-up of 32 months (range, 12–45 months). EverPatch is the first synthetic, nondegradable tissue substitute developed for ocular surface surgery. A study evaluating its use for GDD tube coverage reported a significantly increased rate of early conjunctival complications leading to tube exposure compared with processed, irradiated donor corneal patch grafts (43). Longer-term studies are needed to verify the safety profile and tube exposure rates associated with these synthetic materials.

Tube insertion sites

Anterior chamber tube placement is associated with higher tube erosion rates than posterior placements, due to increased contact between the tube and conjunctiva and increased eyelid-related friction. Minckler et al. (44) reported that tube erosion most frequently occurs near the corneoscleral junction after anterior chamber insertion. Alobaida et al. (45) compared anterior chamber and ciliary sulcus tube placement and found significantly lower rates of severe complications, including implant exposure, in the ciliary sulcus group (4.4%) than in the anterior chamber group (21.7%). Joos et al. (46) reported cases of recurrent tube erosion due to anterior chamber placement that resolved after repositioning the tube into the vitreous cavity. These findings suggest that posterior tube placement may be associated with a lower rate of tube erosion. However, robust head-to-head comparisons among anterior chamber, ciliary sulcus, and pars plana sites remain limited.

Concomitant ocular surgeries

Concomitant ocular surgery has been associated with an increased risk of tube erosion. In a retrospective case-control study, Trubnik et al. (33) analyzed 339 eyes and found that concomitant surgical procedures performed during GDD implantation significantly increased the risk of tube erosion. The most frequently performed procedures were pars plana vitrectomy (35.0%) and cataract extraction with intraocular lens implantation (32.0%). Additional interventions include orphan trabeculectomy, penetrating keratoplasty, bleb needling, K-prosthesis, cyclophotocoagulation, and intraocular lens exchange.

The rate of concomitant surgery was 35.7% in the erosion group, compared with 17.4% in the non-erosion group (P=0.02). Notably, several studies have suggested that concomitant phacoemulsification may be associated with a higher risk of tube exposure than GDD surgery alone (16,33). However, other studies have indicated that adding phacoemulsification does not increase the risk of tube exposure, particularly when the conjunctiva is healthy (47,48). The available evidence on concomitant phacoemulsification remains inconclusive. Current evidence suggests that the relationship between concomitant phacoemulsification and tube exposure is multifactorial and may depend more on ocular surface condition and surgical factors than on phacoemulsification.

Campagnoli et al. (49) retrospectively evaluated outcomes of combined pars plana vitrectomy and BGI placement in patients with refractory glaucoma. The tube was inserted through the pars plana into the vitreous cavity and covered anteriorly with a donor corneal or scleral patch graft. During a follow-up period exceeding 1 year, tube exposure occurred in only one of 92 eyes. Jeong et al. (50) retrospectively assessed 11 patients with NVG secondary to proliferative diabetic retinopathy who underwent 23-gauge sutureless vitrectomy combined with pars plana placement of an AGI. No cases of tube erosion were observed over a mean follow-up of 12.2 months (range, 8–25 months). For patients requiring combined GDD surgery and pars plana vitrectomy, placing the tube in the pars plana rather than the anterior chamber may help mitigate the risk of tube erosion associated with combined procedures.

Other risk factors

Length of follow-up

Stewart et al. (8) identified longer follow-up duration as a significant risk factor for tube exposure (P=0.001), reporting that tube exposure can occur anytime within the first 5 years following GDD surgery. Progressive patch graft degradation over time may lead to tube exposure. Xia et al. (18) used a scleral patch graft grading scale to demonstrate that scleral patch grafts degrade gradually after GDD surgery, with the most significant degradation occurring after 12 months postoperatively.

Anti-VEGF therapy

Liu et al. (51) conducted a retrospective study evaluating the relationship between tube erosion and intravitreal anti-VEGF injections in 150 patients with age-related macular degeneration (AMD), and found no statistically significant difference in the overall incidence of tube erosion between patients who received anti-VEGF therapy (15 of 309 tubes, 4.8%) and those who did not (12 of 459 tubes, 2.6%; P=0.10). However, patients receiving anti-VEGF therapy experienced a significantly higher average number of tube erosion events (2.1±0.7 events) than those not receiving anti-VEGF therapy (1.3±0.7 events; P<0.01). The authors concluded that patients receiving anti-VEGF injections for AMD are more likely to experience recurrent tube erosion events. In addition, they proposed that the observed association between anti-VEGF therapy and recurrent tube erosion may reflect the physiological role of VEGF in wound healing. VEGF is involved in the proliferative phase of tissue repair, contributing to angiogenesis, fibroblast activation, and extracellular matrix remodeling. VEGF inhibition may impair cellular turnover and matrix remodeling in the conjunctival tissue overlying tube shunts.

Current literature lacks a consistent and standardized approach to identifying risk factors for tube erosion, resulting in inconsistent or inconclusive findings. These discrepancies are likely related to differences in study populations and methodologies. Consequently, current risk prediction remains imprecise and insufficiently individualized for clinical decision-making.

Preventive strategies for tube erosion and exposure

Patch graft materials, such as amniotic membrane-umbilical cord (AM-UC) and double-thickness pericardium, have demonstrated favorable outcomes with low rates of tube erosion (7,52).

Sheha et al. (52) evaluated the effectiveness of AM-UC in preventing tube erosion in a multicenter prospective randomized clinical study by comparing AM-UC grafts with pericardium patch grafts for GDD tube coverage using sequential anterior segment optical coherence tomography. No statistically significant difference was observed in the tube exposure rates between the AM-UC and pericardium groups (P=0.54); however, the AM-UC group exhibited better host-tissue integration and significantly less graft thinning than the pericardium group. Early graft thinning (within 3 months) occurred in 5 eyes (12%) and 17 eyes (43%) in the AM-UC and pericardium groups, respectively (P=0.002). Late graft thinning was observed in 2 eyes (5%) in the AM-UC group and 11 eyes (28%) in the pericardium group (P=0.007). Furthermore, AM-UC grafts demonstrated superior translucency and cosmetic appearance compared with pericardium grafts.

Several surgical techniques that use the patient’s scleral tissue have been proposed as alternatives to patch grafts to flatten the tube profile and reduce tube motility. In a retrospective study of 27 eyes, the outcomes of AVG implantation using a long scleral flap combined with Tenon advancement and duplication were evaluated (53). A 10-mm scleral flap was created to completely cover the extraocular portion of the tube, and the anterior chamber was entered 2 mm posterior to the limbus beneath the scleral flap using a 23-gauge needle. Notably, no cases of tube erosion were observed during a mean follow-up of 21.7 months.

For the scleral tunnel technique, the long and tandem double scleral tunnels, with or without patch grafts, have been reported. In a retrospective study of 35 consecutive patients who underwent Molteno implant surgery, a 5–6 mm scleral tunnel was created using a 20-gauge microvitreoretinal knife to cover the tube (54). Over 4 years of follow-up, no cases of conjunctival dehiscence or tube exposure were observed. The authors attributed positive outcomes to the absence of immune-mediated processes typically associated with thinning and resorption of patch grafts.

Puthuran et al. (20) conducted a retrospective study of 215 adult eyes and 111 pediatric eyes that received the Aurolab Aqueous Drainage Implant and compared the outcomes of a 4-mm scleral tunnel created with a 23-gauge needle, with and without patch graft placement. When a patch graft was used, tube exposure occurred in 1.4% of adult eyes and 7% of pediatric eyes, whereas no tube exposure occurred in either adult or pediatric eyes without patch grafts at 2-year follow-up. In 5-year retrospective case series by Youn and Yan (29), 204 eyes from 183 patients underwent AGV implantation using a long scleral tunnel without patch grafts. In their study, a scleral tunnel was created with a crescent blade, entering 7 mm and exiting 3 mm posterior to the limbus. Then, a 22-gauge needle was inserted at the anterior opening of the tunnel and advanced towards the anterior chamber. At 5 years, the tube exposure rate was 6.9%, which aligns with the 6–14.5% range reported in retrospective cohort studies of AGV implantation using patch grafts with similar follow-up. In addition, Fahy et al. (13) described a double scleral tunnel technique combined with coverage of the entire tube using a double-layer pericardium patch in 46 eyes. A 23-gauge needle was used to create a 3-mm partial-thickness scleral tunnel near the GDD plate, followed by a second partial-thickness scleral tunnel created 2.5 mm posterior to the limbus for anterior chamber entry. Over a mean follow-up of 27.7 months, no cases of tube erosion were observed.

Collectively, these studies suggest that the risk of tube erosion following GDD surgery may depend less on the presence of a patch graft and more on long-term tube stability within the scleral tissue. Puthuran et al. (20) reported no tube exposure using a long, curved scleral tunnel without a patch graft, proposing that embedding the tube within the sclera reduces surface irregularity, mechanical friction, and chronic inflammation. In contrast, Youn and Yan (29) observed a 6.9% tube exposure rate at 5 years after AGV implantation using a long scleral tunnel without patch grafts, comparable to rates reported with conventional patch graft techniques, potentially reflecting differences in follow-up duration and GDD characteristics (including tube rigidity, with Ahmed tubes being relatively stiffer). Notably, Fahy et al. (13) reported zero tube erosion using a double scleral tunnel combined with double-layer pericardium coverage, suggesting that firm scleral fixation minimizing tube micro-movements may be critical in reducing mechanical stress at the conjunctival interface.

Table 5 summarizes comparative studies evaluating preventive strategies for tube erosion (6,7,9,24,52,55). These data indicate that techniques incorporating scleral tunneling are associated with lower tube exposure rates than conventional overlay patch grafting, likely by reducing tube micro-movements and mechanical stress at the conjunctival interface. Scleral tunnel techniques are increasingly adopted in clinical practice; however, their use remains inconsistent, as these procedures are technically demanding and may be challenging in eyes with thin sclera or extensive conjunctival scarring. Therefore, well-designed prospective randomized trials directly comparing scleral tunnel techniques with conventional patch grafting are critically needed to better define their relative efficacy, safety, and appropriate indications.

Repair of tube erosion and exposure

Managing tube erosion/exposure is challenging. Reported rates of re-erosion following tube repair are relatively high, ranging from 0% to 45% in the recent literature (56-64).

Dubey et al. (65) described the successful treatment of early tube exposure occurring 1 month after GDD surgery with oral doxycycline and topical prednisolone. In contrast, late tube exposure usually requires surgical rather than medical management. Successful surgical repair involves evaluating for associated infection, assessing the site and extent of implant exposure, confirming GDD function, and examining the surrounding conjunctival health (17). GDD function can be determined by the adequacy of IOP control and the appearance of the bleb over the plate (17). After adequate conjunctival mobilization, the conjunctival epithelial “underpass” that has formed beneath the exposed tube should be scraped or dissected from the episcleral surface and removed (66). This step helps minimize the risk of re-exposure, as buried epithelium tends to migrate toward the surface.

Various surgical techniques are available for repairing tube exposure, and the surgical approach should be tailored to the underlying cause. Neti et al. (61) proposed several key principles. First, when exposure stems from mechanical friction between the tube and conjunctiva, the tube should be securely fixed to the sclera. Second, when patch graft dissolution is suspected, adequate coverage of the tube with a durable graft material is essential. Third, if conjunctival compromise is present, suitable conjunctival substitutes should be considered. Finally, other modifiable factors, including medications and systemic conditions that may adversely affect wound healing, should be addressed. Adhering to these guidelines may improve the likelihood of successful repair.

The tube can be firmly secured to the sclera by suturing it directly to the underlying sclera (66). This technique flattens the tube curvature, reduces mobility, and minimizes mechanical friction. Huddleston et al. (57) recommended using nylon rather than polyester sutures, as the latter may increase the risk of tube re-exposure due to mechanical friction or immunological reactions.

Alternative strategies include tube repositioning or rerouting. Tube rerouting involves altering the path of the tube, which modifies the mechanical forces between the tube and the overlying tissues, thereby potentially reducing the risk of re-exposure. Repositioning options include placement in the ciliary sulcus or the pars plana after complete vitrectomy, both of which aim to reduce anterior segment friction. Kang et al. (67) described a technique for repositioning the tube from the anterior chamber to the ciliary sulcus. After injecting an ophthalmic viscoelastic device into the ciliary sulcus through a limbal paracentesis, a bent 20-gauge microvitreoretinal blade is used to access the ciliary sulcus approximately 4 mm posterior to the limbus, maintaining a plane parallel to the iris. The tube is then removed from the anterior chamber, trimmed with a bevel-down configuration, and inserted through the newly created track. Joos et al. (46) reported that in cases of recurrent tube exposure previously managed with pericardial or scleral patch grafts, repositioning the tube from the anterior chamber into the vitreous cavity following complete vitrectomy and removal of vitreous around the tube entry site. Notably, no participant experienced recurrent exposure.

In eyes with insufficient conjunctival tissue for repair, often seen in cases of recurrent tube erosions or significant conjunctival scarring and immobility, amniotic membrane or a buccal mucous membrane graft harvested from the lower lip can be effective. Ainsworth et al. (68) reported successful management of tube erosion using a double-layer amniotic membrane technique. In their approach, the first layer was placed over the scleral patch with the epithelial side facing upward, followed by a second layer applied over the conjunctival epithelial defect. Rootman et al. (69) described a technique combining a buccal mucous membrane graft with a split-thickness corneal graft, which effectively repaired five of six cases of tube erosion. They recommended this approach as an alternative because the buccal mucous membrane is readily accessible and provides abundant tissue for superficial coverage of eroded tubes.

Chen et al. (70) recently reported that treatment with 0.1% tacrolimus eye drops yielded favorable outcomes in managing recurrent exposure after allogeneic scleral patch graft coverage and autologous scleral tunnel repair. In their retrospective comparative case study, treatment success was defined as cessation of conjunctival dissolution around the AGV tube without further enlargement of the affected area.

A consistent limitation in the literature is the lack of standardized treatment protocols. Considerable variability in surgical techniques among surgeons hinders meaningful comparison of outcomes, including recurrence, infection risk, and long-term IOP control. In addition, the optimal timing of intervention remains undefined, reflecting insufficient solid evidence to guide clinical decision-making.

Strengths and limitations

This narrative review provides a synthesis of the available literature on tube erosion and exposure following GDD surgery, integrating evidence from clinical studies, meta-analyses, case series, and case reports to present an up-to-date overview of current knowledge and ongoing controversies. The detailed discussion of preventive and repair strategies is intended to enhance surgical understanding and practical applicability.

However, some limitations should also be acknowledged. As a narrative review, this study relies on published studies with heterogeneous designs and reporting standards, and formal quantitative synthesis or risk-of-bias assessment was not performed. Consequently, the conclusions are limited by the quality and consistency of the existing evidence. Nonetheless, by critically appraising current data and highlighting unmet needs, this review provides adequate information to inform clinical practice and guide future research directions.

Conclusions

Tube erosion and exposure are clinically important complications of GDD surgery, with substantial risks for endophthalmitis and compromised long-term IOP control. Increased risk of tube erosion/exposure has been associated with several patient-related factors, including age, female sex, and specific ethnic backgrounds, as well as ocular comorbidity-related factors such as prior ocular surgery, inflammation, NVG, and uveitic glaucoma. In addition, surgical factors, particularly combined procedures, tube shunt location, and tube insertion site, also appear to influence erosion risk. Multiple risk factors have been proposed; however, existing evidence is predominantly derived from heterogeneous retrospective studies, limiting robust conclusions regarding true incidence, underlying mechanisms, and optimal management strategies.

Preventive techniques using scleral tunnel approaches or double-thickness pericardium patch grafts have been associated with lower rates of erosion/exposure in multiple studies. Notably, this review supports a mechanistic paradigm in which control of tube micro-movements and mechanical stress at the conjunctival interface, rather than graft material alone, may play a central role in preventing tube erosion. Successful tube repair requires identifying and correcting the underlying cause of exposure, including secure scleral fixation to reduce mechanical friction, repositioning or rerouting of the tube, durable graft coverage to prevent graft dissolution, appropriate conjunctival reconstruction when tissue integrity is compromised, and optimization of modifiable local and systemic factors that affect wound healing. Nevertheless, preventive and repair approaches remain highly variable across institutions and surgeons, reflecting the lack of clear criteria for risk assessment and robust comparative evidence.

Future research should focus on standardized outcome reporting, multicenter investigations, mechanistic studies linking clinical findings to tissue responses, and well-designed prospective comparative trials to improve the prevention and management of this potentially vision-threatening complication.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editors (Etsuo Chihara & Keith Barton & Ronald Fellman & Akira Matsuda) for the series “Recent Glaucoma Surgeries” published in Annals of Eye Science. The article has undergone external peer review.

Reporting Checklist: The author has completed the Narrative Review reporting checklist. Available at https://aes.amegroups.com/article/view/10.21037/aes-25-62/rc

Peer Review File: Available at https://aes.amegroups.com/article/view/10.21037/aes-25-62/prf

Funding: None.

Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://aes.amegroups.com/article/view/10.21037/aes-25-62/coif). The series “Recent Glaucoma Surgeries” was commissioned by the editorial office without any funding or sponsorship. The author has no other conflicts of interest to declare.

Ethical Statement: The author is accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All clinical procedures described in this study were performed in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patients for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Gedde SJ, Schiffman JC, Feuer WJ, et al. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol 2012;153:789-803.
2. Arora KS, Robin AL, Corcoran KJ, et al. Use of Various Glaucoma Surgeries and Procedures in Medicare Beneficiaries from 1994 to 2012. Ophthalmology 2015;122:1615-24. [Crossref] [PubMed]
3. Gedde SJ, Scott IU, Tabandeh H, et al. Late endophthalmitis associated with glaucoma drainage implants. Ophthalmology 2001;108:1323-7. [Crossref] [PubMed]
4. Heuer DK, Budenz D, Coleman A. Aqueous shunt tube erosion. J Glaucoma 2001;10:493-6. [Crossref] [PubMed]
5. Bains U, Hoguet A. Aqueous Drainage Device Erosion: A Review of Rates, Risks, Prevention, and Repair. Semin Ophthalmol 2018;33:1-10. [Crossref] [PubMed]
6. Ollila M, Falck A, Airaksinen PJ. Placing the Molteno implant in a long scleral tunnel to prevent postoperative tube exposure. Acta Ophthalmol Scand 2005;83:302-5. [Crossref] [PubMed]
7. Lankaranian D, Reis R, Henderer JD, et al. Comparison of single thickness and double thickness processed pericardium patch graft in glaucoma drainage device surgery: a single surgeon comparison of outcome. J Glaucoma 2008;17:48-51. [Crossref] [PubMed]
8. Stewart WC, Kristoffersen CJ, Demos CM, et al. Incidence of conjunctival exposure following drainage device implantation in patients with glaucoma. Eur J Ophthalmol 2010;20:124-30. [Crossref] [PubMed]
9. Wigton E, C, Swanner J, Joiner W, et al. Outcomes of shunt tube coverage with glycerol preserved cornea versus pericardium. J Glaucoma 2014;23:258-61. [Crossref] [PubMed]
10. Muir KW, Lim A, Stinnett S, et al. Risk factors for exposure of glaucoma drainage devices: a retrospective observational study. BMJ Open 2014;4:e004560. [Crossref] [PubMed]
11. Budenz DL, Feuer WJ, Barton K, et al. Postoperative Complications in the Ahmed Baerveldt Comparison Study During Five Years of Follow-up. Am J Ophthalmol 2016;163:75-82.
12. Edo A, Jian K, Kiuchi Y. Risk factors for exposure of Baerveldt glaucoma drainage implants: a case-control study. BMC Ophthalmol 2020;20:364. [Crossref] [PubMed]
13. Fahy ET, Garg A, Lim KS. Double scleral tunnel technique to prevent glaucoma drainage device exposure. Eur J Ophthalmol 2023;33:1495-500. [Crossref] [PubMed]
14. Christakis PG, Kalenak JW, Tsai JC, et al. The Ahmed Versus Baerveldt Study: Five-Year Treatment Outcomes. Ophthalmology 2016;123:2093-102. [Crossref] [PubMed]
15. Geffen N, Buys YM, Smith M, et al. Conjunctival complications related to Ahmed glaucoma valve insertion. J Glaucoma 2014;23:109-14. [Crossref] [PubMed]
16. Smith MF, Doyle JW, Ticrney JW Jr. A comparison of glaucoma drainage implant tube coverage. J Glaucoma 2002;11:143-7. [Crossref] [PubMed]
17. Lun KW, Chew PTK, Lim DKA. Glaucoma drainage implant exposure: A review of aetiology, risks and repair considerations. Clin Exp Ophthalmol 2022;50:781-92. [Crossref] [PubMed]
18. Xia T, Khouri AS. Scleral Patch Graft Melt After Tube Shunt Surgery: Grading and Identification of Risk Factors. J Glaucoma 2018;27:717-22. [Crossref] [PubMed]
19. Rai P, Lauande-Pimentel R, Barton K. Amniotic membrane as an adjunct to donor sclera in the repair of exposed glaucoma drainage devices. Am J Ophthalmol 2005;140:1148-52. [Crossref] [PubMed]
20. Puthuran GV, Palmberg P, Wijesinghe HK, et al. Aurolab Aqueous Drainage Implant With and Without Scleral Patch Graft in Refractory Adult and Pediatric Glaucomas: A Comparative Study. Am J Ophthalmol 2020;216:226-36. [Crossref] [PubMed]
21. Oana S, Vila J. Tube Exposure Repair. J Curr Glaucoma Pract 2012;6:139-42. [Crossref] [PubMed]
22. Ma XH, Du XJ, Liu B, et al. Modified Scleral Tunnel to Prevent Tube Exposure in Patients With Refractory Glaucoma. J Glaucoma 2016;25:883-5. [Crossref] [PubMed]
23. Eslami Y, Azaripour E, Mohammadi M, et al. Single long scleral tunnel technique for prevention of Ahmed valve tube exposure. Eur J Ophthalmol 2019;29:52-6. [Crossref] [PubMed]
24. Kugu S, Erdogan G, Sevim MS, et al. Efficacy of long scleral tunnel technique in preventing Ahmed glaucoma valve tube exposure through conjunctiva. Semin Ophthalmol 2015;30:1-5. [Crossref] [PubMed]
25. Chaku M, Netland PA, Ishida K, et al. Risk factors for tube exposure as a late complication of glaucoma drainage implant surgery. Clin Ophthalmol 2016;10:547-53. [Crossref] [PubMed]
26. Al-Beishri AS, Malik R, Freidi A, et al. Risk Factors for Glaucoma Drainage Device Exposure in a Middle-Eastern Population. J Glaucoma 2019;28:529-34. [Crossref] [PubMed]
27. Koval MS, El Sayyad FF, Bell NP, et al. Risk factors for tube shunt exposure: a matched case-control study. J Ophthalmol 2013;2013:196215. [Crossref] [PubMed]
28. Jomar DE, Al-Shahwan S, Al-Beishri AS, et al. Risk Factors for Glaucoma Drainage Device Exposure in Children: A Case-Control Study. Am J Ophthalmol 2023;245:174-83. [Crossref] [PubMed]
29. Youn S, Yan DB. Five-Year Outcomes of Graft-Free Tube Shunts and Risk Factors for Tube Exposures in Glaucoma. J Glaucoma 2024;33:139-47. [Crossref] [PubMed]
30. Byun YS, Lee NY, Park CK. Risk factors of implant exposure outside the conjunctiva after Ahmed glaucoma valve implantation. Jpn J Ophthalmol 2009;53:114-9. [Crossref] [PubMed]
31. Levinson JD, Giangiacomo AL, Beck AD, et al. Glaucoma drainage devices: risk of exposure and infection. Am J Ophthalmol 2015;160:516-521.
32. Broadway DC, Chang LP. Trabeculectomy, risk factors for failure and the preoperative state of the conjunctiva. J Glaucoma 2001;10:237-49. [Crossref] [PubMed]
33. Trubnik V, Zangalli C, Moster MR, et al. Evaluation of Risk Factors for Glaucoma Drainage Device-related Erosions: A Retrospective Case-Control Study. J Glaucoma 2015;24:498-502. [Crossref] [PubMed]
34. Zhou D, Zhou XY, Mas-Ramirez AM, et al. Factors Associated with Conjunctival Erosions after Ahmed Glaucoma Valve Implantation. J Ophthalmic Vis Res 2018;13:411-8. [Crossref] [PubMed]
35. Owen CG, Newsom RS, Rudnicka AR, et al. Vascular response of the bulbar conjunctiva to diabetes and elevated blood pressure. Ophthalmology 2005;112:1801-8. [Crossref] [PubMed]
36. Prinz J, Mercieca K, Förster LJ, et al. Tube erosions following glaucoma drainage device implantations. Sci Rep 2025;15:26056. [Crossref] [PubMed]
37. Wang S, Gao X, Qian N. The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma: a meta-analysis. BMC Ophthalmol 2016;16:83. [Crossref] [PubMed]
38. Milla E, Izquierdo J, Sanchez Dalmau B. Surgical Repair of the Extrusion of the Body of a PAUL Implant for Glaucoma. Case Rep Ophthalmol 2022;13:671-7. [Crossref] [PubMed]
39. Vallabh NA, Mason F, Yu JTS, et al. Surgical technique, perioperative management and early outcome data of the PAUL® glaucoma drainage device. Eye (Lond) 2022;36:1905-10. [Crossref] [PubMed]
40. Koh V, Chew P, Triolo G, et al. Treatment Outcomes Using the PAUL Glaucoma Implant to Control Intraocular Pressure in Eyes with Refractory Glaucoma. Ophthalmol Glaucoma 2020;3:350-9. [Crossref] [PubMed]
41. Ekici F, Moster MR, Cvintal V, et al. Tube shunt coverage with gamma-irradiated cornea allograft (VisionGraft). Clin Ophthalmol 2015;9:751-5. [Crossref] [PubMed]
42. Stephens JD, Sarkisian SR Jr. The use of collagen matrix (Ologen) as a patch graft in glaucoma tube shunt surgery, a retrospective chart review. F1000Res 2016;5:1898. [Crossref] [PubMed]
43. Kanter J, Garkal A, Cardakli N, et al. Early Postoperative Conjunctival Complications Leading to Exposure of Surgically Implanted CorNeat EverPatch Devices. Ophthalmology 2025;132:799-814. [Crossref] [PubMed]
44. Minckler DS, Francis BA, Hodapp EA, et al. Aqueous shunts in glaucoma: a report by the American Academy of Ophthalmology. Ophthalmology 2008;115:1089-98. [Crossref] [PubMed]
45. Alobaida IA, Malik R, Ahmad S. Comparison of surgical outcomes between sulcus and anterior chamber implanted glaucoma drainage devices. Saudi J Ophthalmol 2020;34:1-7. [Crossref] [PubMed]
46. Joos KM, Laviña AM, Tawansy KA, et al. Posterior repositioning of glaucoma implants for anterior segment complications. Ophthalmology 2001;108:279-84. [Crossref] [PubMed]
47. Hoffman KB, Feldman RM, Budenz DL, et al. Combined cataract extraction and Baerveldt glaucoma drainage implant: indications and outcomes. Ophthalmology 2002;109:1916-20. [Crossref] [PubMed]
48. Chung AN, Aung T, Wang JC, et al. Surgical outcomes of combined phacoemulsification and glaucoma drainage implant surgery for Asian patients with refractory glaucoma with cataract. Am J Ophthalmol 2004;137:294-300. [Crossref] [PubMed]
49. Campagnoli TR, Kim SS, Smiddy WE, et al. Combined pars plana vitrectomy and Baerveldt glaucoma implant placement for refractory glaucoma. Int J Ophthalmol 2015;8:916-21. [Crossref] [PubMed]
50. Jeong HS, Nam DH, Paik HJ, et al. Pars plana Ahmed implantation combined with 23-gauge vitrectomy for refractory neovascular glaucoma in diabetic retinopathy. Korean J Ophthalmol 2012;26:92-6. [Crossref] [PubMed]
51. Liu KC, Gomez-Caraballo M, Challa P, et al. Recurrent Tube Erosions with Anti-Vascular Endothelial Growth Factor Therapy in Patients with Age-Related Macular Degeneration. Ophthalmol Glaucoma 2020;3:295-300. [Crossref] [PubMed]
52. Sheha H, Tello C, Al-Aswad LA, et al. Outcomes of the Shunt Tube Exposure Prevention Study: A Randomized Clinical Trial. Ophthalmol Glaucoma 2019;2:392-401. [Crossref] [PubMed]
53. Tamcelik N, Ozkok A, Sarıcı AM, et al. Tenon advancement and duplication technique to prevent postoperative Ahmed valve tube exposure in patients with refractory glaucoma. Jpn J Ophthalmol 2013;57:359-64. [Crossref] [PubMed]
54. Leong JK, McCluskey P, Lightman S, et al. Outcome of graft free Molteno tube insertion. Br J Ophthalmol 2006;90:501-5. [Crossref] [PubMed]
55. Pakravan M, Hatami M, Esfandiari H, et al. Ahmed glaucoma valve implantation: graft-free short tunnel small flap versus scleral patch graft after 1-year follow-up: a randomized clinical trial. Ophthalmology Glaucoma 2018;1:206-12.
56. Grover DS, Merritt J, Godfrey DG, et al. Forniceal conjunctival pedicle flap for the treatment of complex glaucoma drainage device tube erosion. JAMA Ophthalmol 2013;131:662-6. [Crossref] [PubMed]
57. Huddleston SM, Feldman RM, Budenz DL, et al. Aqueous shunt exposure: a retrospective review of repair outcome. J Glaucoma 2013;22:433-8. [Crossref] [PubMed]
58. Low SA, Rootman DB, Rootman DS, et al. Repair of eroded glaucoma drainage devices: mid-term outcomes. J Glaucoma 2012;21:619-22. [Crossref] [PubMed]
59. Einan-Lifshitz A, Belkin A, Mathew D, et al. Repair of Exposed Ahmed Glaucoma Valve Tubes: Long-term Outcomes. J Glaucoma 2018;27:532-6. [Crossref] [PubMed]
60. Gizzi C, Rai P, Barton K. Aqueous shunt exposure repair: outcomes and risk factors for recurrence. Eye (Lond) 2024;38:3065-71. [Crossref] [PubMed]
61. Neti N, Petchyim S, Phongsuphan T, et al. A case series and systematic review: results of surgical management of glaucoma drainage device tube exposure. Siriraj Med J 2024;76:865-75.
62. Rosentreter A, Lappas A, Widder RA, et al. Conjunctival repair after glaucoma drainage device exposure using collagen-glycosaminoglycane matrices. BMC Ophthalmol 2018;18:60. [Crossref] [PubMed]
63. Merrill KD, Suhr AW, Lim MC. Long-term success in the correction of exposed glaucoma drainage tubes with a tube extender. Am J Ophthalmol 2007;144:136-7. [Crossref] [PubMed]
64. Ciulla L, Wang J, Qiu M. Post-operative cosmesis of autologous capsular patch grafts in tube shunt surgery: Case series of 18 eyes. Am J Ophthalmol Case Rep 2025;38:102328. [Crossref] [PubMed]
65. Dubey S, Prasanth B, Acharya MC, et al. Conjunctival erosion after glaucoma drainage device surgery: a feasible option. Indian J Ophthalmol 2013;61:355-7. [Crossref] [PubMed]
66. Kalenak JW. Revision for exposed anterior segment tubes. J Glaucoma 2010;19:5-10. [Crossref] [PubMed]
67. Kang JM, Hsia YC, Han Y. A Novel Technique for Recurrent Tube Exposure Repair. Case Rep Ophthalmol Med 2020;2020:6878025. [Crossref] [PubMed]
68. Ainsworth G, Rotchford A, Dua HS, et al. A novel use of amniotic membrane in the management of tube exposure following glaucoma tube shunt surgery. Br J Ophthalmol 2006;90:417-9. [Crossref] [PubMed]
69. Rootman DB, Trope GE, Rootman DS. Glaucoma aqueous drainage device erosion repair with buccal mucous membrane grafts. J Glaucoma 2009;18:618-22. [Crossref] [PubMed]
70. Chen LL, Chen Y, Fu L, et al. Tacrolimus eye drops treatment for recurrent exposure of the Ahmed glaucoma valve tube. Eur J Med Res 2025;30:669. [Crossref] [PubMed]