Factors Associated with Conjunctival Erosions after Ahmed Glaucoma Valve Implantation

Five-Year Outcomes of Graft-Free Tube Shunts and Risk Factors for Tube Exposures in Glaucoma

PRCIS

Use of a scleral tunnel technique instead of a patch graft can be considered in most cases of tube shunt implantation. Grafts may still be considered in younger (<65 y old) East Asians.

PURPOSE

(1) To assess the risk factors for tube exposure with a graft-free implantation technique and (2) to examine 5-year outcomes of graft-free tube shunt insertion.

METHODS

This was a retrospective case series of 204 consecutive eyes undergoing a glaucoma tube shunt implantation with a scleral tunnel technique in lieu of a graft. Preoperative and postoperative best-corrected visual acuity, intraocular pressure, and number of glaucoma medications were compared. Failure was defined as the following: (1) intraocular pressure >21 mm Hg or ≤5 mm Hg on 2 consecutive visits after 3 mo; (2) required additional glaucoma surgery; (3) loss of light perception. Univariable and multivariable regression analyses were conducted to identify risk factors of tube exposures.

RESULTS

Intraocular pressure and the number of glaucoma medications were significantly decreased at all postoperative time points ( P <0.001). Success rates were 91% at year 1, 75% at year 3, and 67% at year 5. The most common early (<3 mo) complication was tube malpositioning. The most common late (>3 mo to 5 y) complications were corneal complications and uncontrolled intraocular pressure. By year 5, 6.9% of tubes were exposed. Multivariable regression showed that age less than 65 years old (odds ratio: 3.66, P =0.04) and East Asian ethnicity (odds ratio: 3.36, P =0.04) were associated with significantly increased risk of tube exposure.

CONCLUSIONS

Graft-free glaucoma tube implantation has comparable long-term outcomes and complication rates to shunts with a graft. Younger (<65 y old) East Asians are at greater risk of tube exposure without a graft.

Limbal reconstruction in uveitic glaucoma patient with exposed Ahmed valve coincident with corneal melting and iris prolapse using multiple corneoscleral allografts

Aim: To present a complex case of Ahmed tube exposure 6 months after the implantation associated with corneal melting and iris prolapse, and the surgical reposition that required multiple allografts and limbal reconstruction. Methods: A 60-year-old patient arrived at the emergency room with tube exposure combined with corneal melting and iris prolapse from a previously placed Ahmed valve 6 months prior. Our approach was to use one corneoscleral graft to repair the melted cornea and avoid further iris prolapse and a second scleral graft to cover the repositioned tube. Upon completion of conjunctival dissection, cleaning and deepithelization of the melted cornea and the tube by application of alcohol 100% followed. A new entry point was made for the tube and was covered using an alcohol-preserved scleral allograft and the previous entry point was repaired using a corneoscleral allograft with the corneal aspect restoring the limbus and avoiding further iris protrusion. Results: 6 months follow-up of the patient showed excellent recovery, anatomical restoration, and IOP normalization. Conclusion: Surgical repair of these cases can be very demanding, and requires surgical improvisation and prolonged surgical time. The literature remains very limited on how a surgeon should approach similar cases, which are the crucial tips, and which are the missteps that should be avoided. In this case, we used multiple scleral/corneoscleral allografts in a specific orientation and different sutures to reconstruct the damaged limbal area and restore the anatomy. Abbreviations: VA = Visual Acuity, GDD = Glaucoma Drainage Device, IOP = Intra Ocular Pressure.

Risk Factors for Glaucoma Drainage Device Exposure in Children: A Case-Control Study

PURPOSE

To identify the risk factors for glaucoma drainage device (GDD) exposure in children.

DESIGN

Retrospective case-control study.

METHODS

The study population comprised children (one eye each) who presented with a history of GDD exposure to a tertiary care eye hospital over the period January 2014 to January 2020. Consecutive children (age <18 years) were included. A control group from the same time period (children without GDD exposure) were included in the ratio of 5 controls to every 1 case of exposure. The main outcome measures included risk factors for exposure (univariate and multivariate analysis).

RESULTS

A total of 21 eyes (of 21 children with implant exposure) and 115 eyes (of 115 children without exposure) were included in this study. During the same study period, a total of 494 eyes had undergone GDD implantation, giving an estimated incidence of exposure of 4.25%). In the bivariate analysis, GDD exposure was associated with multiple previous ocular surgeries (P = .001), longer follow-up duration (P < .001), combined procedure at the time of primary implantation (P = .002), and a younger age at the time of primary implantation (P = .006). The former 3 risk factors continued to prove a statistically significant association on multivariable regression analysis. Postoperative use of eye lubricants was more common among children in the control group (P = .007).

CONCLUSION

In pediatric glaucoma patients, younger age and combined procedure at the time of primary GDD implantation, in addition to multiple previous ocular surgeries, were associated with greater risk of implant exposure. Postoperative use of eye lubricants may be protective.

Long-term surgical outcomes of two different Ahmed Valve implantation techniques in refractory glaucoma: Scleral flap vs scleral tunnel

PURPOSE

To compare the outcomes and complications of the partial-thickness scleral flap technique to the long scleral tunnel technique in patients who underwent mitomycin C (MMC)-augmented Ahmed glaucoma valve (AGV) implantation.

PATIENTS AND METHODS

In this retrospective study, we reviewed 139 eyes of 137 patients with refractory glaucoma who underwent AGV-Model FP7 implantation. The eyes were divided into the scleral flap group (n = 74) and the scleral tunnel group (n = 65).

RESULTS

The mean follow-up was 57.91 ± 18.18 months for the flap and 61.18 ± 15.13 months for the tunnel group (p = 0.2499). The postoperative intraocular pressure (IOP) at 1 to 6 years was significantly lower than the baseline IOP in each group (p < 0.001). The average number of postoperative glaucoma medications decreased in the tunnel group (p = 0.0001) and in the flap group (p = 0.6194) compared to baseline. No statistically significant differences in postoperative visual acuity (p = 0.6396) and cumulative success (p = 0.054) were noted between the two groups. Conjunctival erosion or tube migration only occurred in the flap group. Significantly more reoperations were performed in the flap than in the tunnel group (p = 0.048).

CONCLUSIONS

Both MMC-augmented AGV tube implantation methods lowered IOP. The flap technique was associated with higher rates of postoperative serious complications and more reoperations than the tunnel technique. Previous glaucoma surgery and the technique used to implant the surgical tube proved to be significant risk factors for conjunctival erosion.

Risk Factors for Glaucoma Drainage Device Revision or Removal Using the IRIS Registry

PURPOSE

To elucidate risk factors for revision or removal of glaucoma drainage devices (GDD) in glaucoma patients in the United States.

DESIGN

Retrospective cohort study.

METHODS

IRIS Registry (Intelligent Research in Sight) patients who underwent GDD insertion between January 1, 2013 and December 31, 2018 were included. Various demographic and clinical factors were collected. Kaplan-Meier survival plots, Cox proportional-hazard models utilizing Firth's Penalized Likelihood, and multivariate linear regression models were used. The main outcome measures were hazard ratios (HR) and beta coefficient (β) estimates.

RESULTS

A total of 44,330 distinct patients underwent at least 1 GDD implantation, and 3354 of these underwent subsequent GDD revision or removal surgery. With failure defined as GDD revision/removal, factors significantly associated with decreased failure included unknown race (HR = 0.83; P = .004) and unknown ethnicity (HR = 0.68; P < .001). Factors associated with increased risk of GDD revision/removal surgery included presence of chronic angle-closure glaucoma (HR = 1.32; P < .001) and dry eye disease (HR = 1.30; P = .007). Additionally, factors associated with a decreased average time (in days) to GDD revision/removal included male sex (β = -25.96; P = .044), unknown race (β = -55.28; P = .013), and right-eye laterality (β = -38.67; P = .026). Factors associated with an increased average time to GDD revision/removal included having a history of a past eye procedure (β = 104.83; P < .001) and being an active smoker (β = 38.15; P = .024).

CONCLUSIONS

The size and scope of the IRIS Registry allows for detection of subtle associations between risk factors and GDD revision or removal surgery. The aforementioned demographic and clinical factors may all have an impact on GDD longevity and can inform the treatment options available for glaucoma patients.

Prompt vitrectomy for management of endophthalmitis in setting of unexposed glaucoma drainage implant

Purpose

To highlight a rare case of fulminant endophthalmitis in the late post-operative stage after glaucoma drainage device implantation without evidence of device exposure, and to share the unique management that resulted in successful restoration of vision and intraocular pressure control.

Observations

Endophthalmitis after glaucoma drainage implantation (GDI) is a rare complication most often associated with exposure of the device. Management options are limited, but removal of GDI is a common approach in the setting of an exposed implant. Visual acuity outcomes are often significantly reduced despite adequate treatment. There is little in the existing literature about management of late-onset endophthalmitis in the setting of a GDI without implant exposure. Here we present such a case that was successfully managed by prompt pars plana vitrectomy and removal of tube from the anterior chamber with subsequent re-insertion and patch graft. Our case results in a restoration of baseline visual acuity and IOP control at 7 months follow up.

Conclusions and importance

Endophthalmitis occurring after GDI implantation is a challenging complication to manage. Many physicians resort to removal of device for treatment, and a majority would treat initially with intravitreal antibiotic injection of antibiotics rather than prompt pars plana vitrectomy. This article provides a different approach that avoids removal of the device.

Glaucoma Patch Graft Surgery Utilizing Corneas Augmented with Collagen Cross-linking

PURPOSE

Glaucoma drainage device surgery (GDDS) has gained popularity, with outcomes equivalent to trabeculectomy. Erosion of the tube through the overlying conjunctiva may occur in 5%-10% of eyes. Donor corneal tissue has been used as a patch graft for GDDS.

MATERIALS AND METHODS

This was a prospective proof of concept study in 10 patients undergoing GDDS. From patients undergoing endothelial keratoplasty, the donor tissue (approximately 300 μ in thickness) was placed epithelial side down in a well and was allowed to soak in riboflavin solution (VibeX, Avedro, Waltham, MA, USA) for 15 min. This anterior corneal lenticule received 8 mW/cm² ultraviolet (UV) irradiation applied for 15 min (total energy of 7.2 J/cm²). Each lenticule was then bisected and utilized for the two study participants. The tissue was sutured over the tube during the GDDS and then was covered with recipient conjunctiva as per the usual technique. Representative graft tissues were fixed and examined to determine the depth of cross-linking effect. The patients were followed for 1 year.

RESULTS

Histology revealed no apparent demarcation line in the cross-linked grafts; this supported a full-thickness cross-linking treatment effect. There were no intra- or postoperative complications attributed to the graft tissue. No patient developed erosion or exposure of the tube during the 1-year follow-up.

CONCLUSIONS

UV-riboflavin cross-linking of the corneal tissue patch graft material appears to be a safe modification when used in GDDS and warrants ongoing study. This method of patch graft can replace other costy methods used with GDD.