Coupling of HRT II and AS-OCT to evaluate corneal endothelial cell loss and in vivo visualization of the Ahmed glaucoma valve implant

Postoperative Complications in the Primary Tube Versus Trabeculectomy Study During 5 Years of Follow-up

PURPOSE

To describe postoperative complications encountered in the Primary Tube Versus Trabeculectomy (PTVT) Study during 5 years of follow-up.

DESIGN

Multicenter randomized clinical trial.

PARTICIPANTS

A total of 242 eyes of 242 patients with medically uncontrolled glaucoma and no previous incisional ocular surgery, including 125 patients in the tube group and 117 patients in the trabeculectomy group.

METHODS

Patients were enrolled at 16 clinical centers and randomly assigned to treatment with a tube shunt (350-mm2 Baerveldt glaucoma implant) or trabeculectomy with mitomycin C (MMC, 0.4 mg/ml for 2 minutes).

MAIN OUTCOME MEASURES

Surgical complications, reoperations for complications, visual acuity, and cataract progression.

RESULTS

Early postoperative complications occurred in 24 patients (19%) in the tube group and 40 patients (34%) in the trabeculectomy group (P = 0.013). Late postoperative complications developed in 27 patients (22%) in the tube group and 32 patients (27%) in the trabeculectomy group (P = 0.37). Serious complications producing vision loss and/or requiring a reoperation were observed in 3 patients (2%) in the tube group and 9 patients (8%) in the trabeculectomy group (P = 0.11). Cataract progression was seen in 65 patients (52%) in the tube group and 52 patients (44%) in the trabeculectomy group (P = 0.30). Surgical complications were not associated with a higher rate of treatment failure (P = 0.61), vision loss (P = 1.00), or cataract progression (P = 0.77) CONCLUSIONS: A large number of surgical complications were observed in the PTVT Study, but most were transient and self-limited. The incidence of early postoperative complications was higher following trabeculectomy with MMC than with tube shunt surgery. The rates of late postoperative complications, serious complications, and cataract progression were similar with both surgical procedures after 5 years of follow-up. Surgical complications did not increase the risk of treatment failure, vision loss, or cataract progression.

Tube–Iris Distance and Corneal Endothelial Cell Damage Following Ahmed Glaucoma Valve Implantation

The most significant factor for endothelial cell loss should be readily identified, since prevention is the most crucial treatment. Here, we investigate risk factors for corneal endothelial cell density (ECD) decline following Ahmed glaucoma valve (AGV) implantation and determine the optimal cut-off values. This study included 103 eyes (95 patients) with glaucoma that underwent AGV implantation between January 2006 and January 2021 at a single medical center (Severance Hospital). We conducted consecutive t-tests between two groups separated by the ECD change rate to determine the survival state of the enrolled patients. Associations were evaluated using univariable and multivariable linear regressions. Optimal cut-off values for identified risk factors were analyzed using a Cox proportional hazards model and a receiver operating characteristic (ROC) curve based on logistic regression. Mean follow-up duration was 4.09 ± 2.20 years. After implementing consecutive t-tests, only patients with an ECD change rate greater than −6.1%/year were considered to have survived. Tube–iris distance (TID) was the only statistically significant factor identified in both the univariable and multivariable linear regressions. The cut-off value determined from the consecutive Cox regression method was 0.33 mm (smallest p-value of 0.0087), and the cut-off value determined from the ROC method was 0.371 mm (area under the receiver operating characteristic curve [AUC], 0.662). Patients with short TIDs showed a better ECD prognosis following AGV surgery; we suggest optimal TID cut-off values of 0.33 mm and 0.371 mm based on the implemented Cox regression and ROC methodology, respectively.

Corneal Endothelial Cell Loss in Glaucoma and Glaucoma Surgery and the Utility of Management with Descemet Membrane Endothelial Keratoplasty (DMEK)

The corneal endothelium has a crucial role in maintaining a clear and healthy cornea. Corneal endothelial cell loss occurs naturally with age; however, a diagnosis of glaucoma and surgical intervention for glaucoma can exacerbate a decline in cell number and impairment in morphology. In glaucoma, the mechanisms for this are not well understood and this accelerated cell loss can result in corneal decompensation. Given the high prevalence of glaucoma worldwide, this review aims to explore the abnormalities observed in the corneal endothelium in differing glaucoma phenotypes and glaucoma therapies (medical or surgical including with new generation microinvasive glaucoma surgeries). Descemet membrane endothelial keratoplasty (DMEK) is increasingly being used to manage corneal endothelial failure for glaucoma patients and we aim to review the recent literature evaluating the use of this technique in this clinical scenario.

Three-year outcome of sulcus fixation of Baerveldt glaucoma implant surgery

PURPOSE

The purpose of this study was to evaluate the 3-year surgical outcome of the sulcus fixation of Baerveldt glaucoma implant (BGI), focusing on corneal damage.

METHODS

This prospective observational study included 37 patients who underwent a median of two previous glaucoma surgeries and sulcus fixation of BGI for the first time. Each patient's intraocular pressure (IOP), glaucoma drug score, corneal endothelial cell density (ECD), and logMAR-converted best-corrected visual acuity (VA) were measured preoperatively and postoperatively until 36 months after surgery. Complete success was defined as reduced IOP (5-21 mmHg and >20% rate), without corneal damage (postoperative development of decompensation, unmeasurable ECD, or reduction in ECD of >20%), without loss of light perception, and without additional surgery requirement. Qualified success was defined by excluding the corneal criteria from complete success.

RESULTS

A total of 51% (19/37) patients experienced complete treatment success, whereas 86% (32/37) had qualified success. The median IOP (glaucoma drug score) decreased from 26 mmHg (5) to 15 mmHg (2) at three years postoperatively. The median postoperative ECD (reduction rate) decreased from 1838 cells/cm² preoperatively to 1587 cells/mm² (14%) at one year, 1358 cells/mm² (26%) at two years, and 1228 cells/mm² (33%) at three years postoperatively. One month after surgery, the VA was significantly reduced from preoperative values but did not decline after that.

CONCLUSION

Sulcus fixation of BGI was effective for IOP reduction. However, ECD decreased over time.

Anterior Chamber Versus Ciliary Sulcus Ahmed Glaucoma Valve Tube Placement: Longitudinal Evaluation of Corneal Endothelial Cell Profiles

PRCIS

An Ahmed glaucoma valve (AGV) tube in the ciliary sulcus (CS) is safer for the endothelium. At 4 years of follow-up, there was a significant decrease in endothelial cell count only with anterior chamber (AC) placement.

PURPOSE

Corneal endothelium (CE) damage is one of the most feared long-term complications that can result from glaucoma drainage devices. Nonetheless, there is a lack of studies evaluating longitudinal changes in CE cells. This study aims to compare CE changes after AGV implantation in eyes with AC or CS tube placement.

MATERIALS AND METHODS

This was a retrospective, nonrandomized, longitudinal study of pseudophakic eyes with open-angle glaucoma and medically uncontrolled intraocular pressure that received an AGV. Eyes with additional glaucoma surgeries performed during follow-up were excluded. The main outcome measure was endothelial cell density (ECD), which was evaluated 1 year±2 months and 4 years±2 months postoperatively. The average endothelial cell size (AS) and the distance from the tube tip to the cornea were also evaluated.

RESULTS

Twenty-six eyes from 26 patients, with a mean age of 73±10 years, were included. The tube was placed in the AC in 15 eyes and in the CS in 11 eyes. The eyes with tube placement in the AC showed a significant AS increase (P=0.007) and ECD decrease (P=0.034), whereas eyes with tube placement in the CS had no significant AS (P=0.575) or ECD (P=0.445) change. In the eyes with tube placement in the AC, there was no correlation between DTC and ECD (P=0.260) or AS (P=0.428) changes.

CONCLUSIONS

Tube placement in the AC seems to lead to significant CE cell loss over time, compared with tube placement in the CS.

The Effects of Glaucoma and Glaucoma Therapies on Corneal Endothelial Cell Density

A healthy corneal endothelium is required for corneal clarity. Both the glaucoma disease state and its various forms of treatment can have adverse effects on the corneal endothelium. Both the presence of glaucoma and the magnitude of intraocular pressure elevation are related to endothelial cell loss (ECL). Topical medical therapy, laser procedures, and both traditional surgeries-trabeculectomy and tube-shunts-and newer minimally invasive glaucoma surgeries have variable effects on ECL. This review will summarize the reported effects of glaucoma and its treatment on ECL. Concerns for corneal endothelial cell health should be part of the decision-making process when planning glaucoma therapy for lowering intraocular pressure, with added caution in case of planned device implantation in eyes with preexisting ECL and low endothelial cell density at high risk for corneal endothelial decompensation.

Effect of Head Position and Tube Entry on Corneal Endothelial Cells in Patients with Glaucoma Drainage Implants: A Cross-sectional Study

PURPOSE

To investigate the effect of head tilt on the tube position of the Ahmed glaucoma valve (AGV) implanted in patients with glaucoma and to assess how the head tilt-induced alterations of tube parameters and the level of tube entry influence corneal endothelial cell density (ECD).

METHODS

A total of 29 eyes of 26 patients with AGV implantation were included. Tube-cornea distance, tube-cornea angle, and intracameral tube length were measured using anterior segment optical coherence tomography in three different head positions (neutral, 30° temporalward tilt, and 30° nasalward tilt). The tube entry was assessed using static gonioscopy. ECD was measured using specular microscopy before and after surgery.

RESULTS

The mean tube-cornea distance, tube-cornea angle, and intracameral tube length (neutral: 0.87 ± 0.39 mm, 30.56 ± 5.89˚, and 3.10 ± 0.82 mm, respectively) decreased with head tilts (temporalward: 0.82 ± 0.39 mm, 29.27 ± 5.82˚, and 3.04 ± 0.82 mm, respectively; nasalward: 0.83 ± 0.40 mm, 29.61 ± 6.04˚, and 3.05 ± 0.81 mm, respectively; all p < 0.01). The multivariate analyses found age and the tube insertion level to be associated with postoperative changes in the central ECD (p = 0.039 and 0.013, respectively), and the postoperative follow-up period and tube insertion level to be associated with the difference between the inferonasal and superotemporal ECDs (p = 0.034 and 0.007, respectively).

CONCLUSIONS

Mild alterations of head positions induced changes in the intracameral tube positions of AGV implants; nevertheless, it did not significantly affect ECD loss. However, the eyes with tubes inserted anteriorly to Schwalbe's line may be more susceptible to corneal ECD loss.

Numerical model to predict and compare the hypotensive efficacy and safety of minimally invasive glaucoma surgery devices

Purpose

To predict and compare the hypotensive efficacy of three minimally-invasive glaucoma surgery (MIGS) implants through a numerical model.

Methods

Post-implant hypotensive efficacy was evaluated by using a numerical model and a computational fluid dynamics simulation. Three different devices were compared: the XEN 45 stent (tube diameter, 45 μm), the XEN 63 stent (63 μm) and the PreserFlo microshunt (70 μm). The influence of the filtration bleb pressure (Bp) and tube diameter, length, and position within the anterior chamber (AC) on intraocular pressure (IOP) were evaluated.

Results

Using baseline IOPs of 25, 30 and 50 mmHg, respectively, the corresponding computed post-implant IOPs for each device were as follows: XEN 45: 17 mmHg (29% decrease), 19 mmHg (45%) and 20 mmHg (59%) respectively; XEN 63: 13 mmHg (48%), 13 mmHg (62%), and 13 mmHg (73%); PreserFlo: 12 mmHg (59%), 13 mmHg (73%) and 13 mmHg (73%). At a baseline IOP of 35 mmHg with an increase in the outflow resistance within the Bp from 5 to 17 mmHg, the hypotensive efficacy for each device was reduced as follows: XEN45: 54% to 37%; XEN 63: 74% to 46%; and PreserFlo: 75% to 47%. The length and the position of the tube in the AC had only a minimal (non-significant) effect on IOP (<0.1 mmHg).

Conclusions

This hydrodynamic/numerical model showed that implant diameter and bleb pressure are the two most pertinent determinants of hypotensive efficacy. In distinction, tube length and position in the AC do not significantly influence IOP.

Impact of Phacoemulsification Combined with XEN Gel Stent Implantation on Corneal Endothelial Cell Density: 2-Year Results

INTRODUCTION

Corneal integrity has long been a preoccupation of glaucoma surgeons considering glaucoma drainage device surgery or antimetabolite-enhanced trabeculectomy. Despite having demonstrated a good safety profile and significant intraocular pressure-lowering capacities, the impact of XEN gel stents on endothelial density was never specifically investigated. The purpose of this study is to assess the effect of XEN gel stents on central endothelial cell density (ECD) over 24 months. To achieve this, we compared the effect on ECD of combined XEN surgery with that of a standard phacoemulsification procedure.

METHODS

This was an investigator-initiated, retrospective study, conducted at a single tertiary glaucoma center. Patients with primary or secondary open-angle glaucoma who underwent XEN implantation combined with phacoemulsification between January 2015 and June 2016 were retrospectively enrolled. Patients who had undergone standalone phacoemulsification over the same period of time were enrolled to form the control group of this comparative study. The primary outcome measure was the ECD. Patients who had undergone standalone XEN implantation and patients for whom both a baseline and 24-month ECD could not be obtained were excluded from the analysis. Percentages of ECD reductions were calculated for each studied eye, and the mean of ECD reductions was calculated for each group as well as for subgroups.

RESULTS

Thirty-two eyes of 23 patients (mean age=76.0±7.9 y, 60% female) underwent standalone phacoemulsification (n=15) or combined XEN surgery (n=17) and had an ECD both at baseline and 24-month postoperatively. Mean baseline ECDs were 2568±491 versus 2379±335 cells/mm, respectively (P=0.21). In the combined XEN surgery group, 58.8% of eyes (n=10) required at least 1 mitomycin C (MMC)-enhanced needling revision to maintain their target intraocular pressure. In the standalone phacoemulsification group, ECD decreased by a mean 14.5%, from 2567.7±491.2 to 2196.1±591.9 cell/mm (P=0.072). In the combined XEN surgery group, ECD decreased by a mean 14.3%, from 2378.8±334.7 to 2039.6±451.1 cell/mm (P=0.018). The difference in percentage reduction of ECD between the 2 groups was not statistically significant (P=0.226). Within the combined XEN surgery group, the ECD decreased by a mean of 15.4% in patients who did not undergo needling revisions and by 13.1% in patients who underwent the MMC-augmented procedure (P=0.485). In the 3 patients who underwent >1 needling revision, a 21.3% reduction in ECD was observed, but the difference was not statistically significant (P=0.653). Neither the time of the first needling (P=0.452), the patients' age (P=0.285), or sex (P=0.308) was statistically associated with ECD loss.

DISCUSSION

The present study demonstrated that the XEN gel implant combined with phacoemulsification produces 24-month ECD loss of a similar magnitude to that observed following standalone phacoemulsification. MMC-augmented needling revisions do not appear to have an impact on ECD.

Surgery for glaucoma in modern corneal graft procedures

Glaucoma is a common cause of vision loss after corneal transplantion and is considered a major risk factor for graft failure. Glaucoma may be present before corneal transplant surgery, or increased intraocular pressure may develop after keratoplasty in up to one-third of patients. Pre-existing glaucoma should be controlled before keratoplasty, either medically or surgically. For postkeratoplasty increase in intraocular pressure; identifying the risk factors allows appropiate follow-up and management. Patients undergoing anterior lamellar keratoplasty may take advantage of reduced rates of postkeratoplasty glaucoma. Glaucoma also complicates eyes with endothelial keratoplasties, mostly related to management of intraocular pressure spikes derived from anterior chamber air bubbles. Nevertheless, the severity is less, and the intraocular pressure is more easily controlled when compared with penetrating keratoplasty. Adequate management of glaucoma that develops before or after keratoplasty may save eyes from irreversible damage to the optic nerve and increase graft survival.

Relationship between Tube Parameters and Corneal Endothelial Cell Damage after Ahmed Glaucoma Valve Implantation: A Comparative Study

PURPOSE

We compared the clinical factors, including anterior chamber tube parameters, in patients with and without corneal endothelial cell damage after Ahmed glaucoma valve (AGV) implantation.

METHODS

In this retrospective and comparative case series, patients who underwent AGV implantation were enrolled consecutively. Serial specular microscopy was performed before and after AGV implantation. Patients were divided into two groups depending on whether there was a significant decrease in corneal endothelial cell density (ECD), which was determined by each patient's rate of ECD change (%/year), calculated using linear regression analyses. Tube parameters such as the tube-cornea distance (TCD) and tube-cornea angle (TCA) were measured with anterior segment optical coherence tomography. Clinical factors related to the rate of ECD change were evaluated with regression analyses and compared between the two groups. The tipping point at which tube parameters became significantly associated with the rate of ECD change was identified with broken stick regression analyses.

RESULTS

There were 30 eyes (32.3%) with ECD damage (group 1) and 63 eyes (67.7%) without damage (group 2). The mean rate of ECD change (%/year) was -18.82 ± 22.97 and 2.14 ± 2.93 in groups 1 and 2, respectively (p < 0.001). The TCA was the only clinical factor associated with the rate of ECD change (regression coefficient, β = 1.254, p < 0.001). The tipping point in the TCA was 26.70° (95% confidence interval, CI: 23.75-29.64°). The mean TCD (mm) was 0.98 ± 0.38 and 1.26 ± 0.39 (p = 0.002), and the mean TCA (degrees) was 28.67 ± 7.79 and 36.35 ± 5.35 (p < 0.001) in groups 1 and 2, respectively.

CONCLUSIONS

A wider TCA was protectively associated with the rate of ECD change, and the TCA was significantly narrower in patients with ECD damage. When inserting a tube into the anterior chamber, surgeons should therefore try to secure a wide TCA of about 30°. In patients with a narrow TCA after AGV implantation, increased attention should be directed toward whether ECD decreases continuously.

Determinants of corneal endothelial cell loss after sulcus placement of Ahmed and Baerveldt drainage device surgery

AIM

In patients who underwent multiple intraocular surgeries, we evaluated determinants of decreased corneal endothelial cell density (CECD) after sulcus placement following Ahmed and Baerveldt drainage device surgery.

METHODS

We retrospectively reviewed consecutive patients with glaucoma who underwent sulcus placement with an Ahmed glaucoma valve or a Baerveldt glaucoma implant. We compared presurgical and postsurgical CECD and risk factors for decreased CECD.

RESULTS

We examined 41 eyes of 41 patients. Postsurgical CECD measurements were assessed 2.0±1.0 times during a median follow-up period of 28 months. The mean intraocular pressure (IOP) decreased from 28.4±11.6 mmHg to 12.2±5.3 mmHg 24 months after the operation. At 24 months, CECD decreased 14.6±5.4% after considering the variability in the number and time points of CECD determinations. History of prior surgery and higher preoperative IOP were significantly associated with a trend for a time-dependent decrease in CECD.

CONCLUSIONS

Risk factors for decreased CECD after sulcus placement during Ahmed and Baerveldt drainage device surgery included the number of previous intraocular surgeries and higher presurgical IOP.

Outcome of a low-cost glaucoma drainage device with posterior chamber/pars plana insertion of the tube

INTRODUCTION

The Aurolab aqueous drainage implant (AADI) is a low-cost glaucoma drainage device that is modelled on the Baerveldt glaucoma implant. Studies on AADI have reported absolute success rates of 41.8-93.1% at 1 year. Most studies report on tube placement in the anterior chamber. We report on results of tube insertion in the sulcus/pars plana.

MATERIAL AND METHODS

A retrospective chart review of all patients who had undergone AADI implantation (with insertion of tube in the sulcus/posterior segment) between June 2015 and November 2018 was done. Patients were asked to stop anti-glaucoma medications on the 40th post-operative day.

RESULTS

The mean age was 57.4 ± 13.8 years (n = 30). The mean IOP prior to surgery was 34.4 ± 6.1 mmHg which reduced to 15.4 ± 8.6 mmHg on the 45th post-operative day (p < 0.001). The absolute success at last review was 10% and the qualified success was 80%. The complication rate was 26.7%. Three patients had hypotony related complications noted at/after the 45th day review (none before 40th day). The incidence of ocular motility disturbances was 26.7% though none of the patients reported diplopia. One patient had sideways rotation of the scleral patch graft resulting in tube exposure. This complication was not seen after we shifted to using 9-0 nylon sutures to anchor the graft. Six patients had loss of best corrected visual acuity and one patient developed endophthalmitis. The endophthalmitis was preceded by conjunctival retraction and sloughing off of the scleral patch graft.

DISCUSSION

AADI implantation results in a substantial drop in IOP. However, many patients continue to require anti-glaucoma medications. Allowing overlap of scleral/corneal patch graft onto the scleral flap may be effective in preventing peritubular leak. It may be advisable to use 9-0 nylon sutures to secure the scleral patch graft anti-glaucoma medications can be temporarily suspended after the 40th post-operative day to minimize hypotony related complications. Melting of the scleral patch graft may be an early sign of endophthalmitis. It would be prudent to specifically look for ocular motility problems in patients undergoing AADI implantation.

Corneal Endothelial Cell Loss and Morphometric Changes 5 Years after Phacoemulsification with or without CyPass Micro-Stent

PURPOSE

To characterize long-term changes in corneal endothelial cells after phacoemulsification with or without supraciliary Micro-Stent (Alcon) implantation in eyes with open-angle glaucoma (OAG) and visually significant cataract.

DESIGN

Three-year safety extension of a 2-year randomized clinical trial.

METHODS

Patients from the multicenter Study of an Implantable Device for Lowering Intraocular Pressure in Glaucoma Patients Undergoing Cataract Surgery (COMPASS) trial who underwent Micro-Stent implantation plus phacoemulsification (n = 282) or phacoemulsification alone (n = 67) were analyzed post hoc. Specular microscopy was used to assess endothelial cell loss (ECL), including changes from baseline in endothelial cell density (ECD), coefficient of variation, and percentage of hexagonal cells.

RESULTS

Preoperative ECDs in the microstent group (2,432.6 cells/mm² [95% confidence interval [CI], 2,382.8-2,482.4 cells/mm²]) were similar to those in the control group (2,434.5 cells/mm² [95% CI, 2,356.5-2,512.4 cells/mm²]) groups. ECL at months 48 and 60 was greater in the Micro-Stent group than in the control group. At month 60, the mean percent of changes in ECD was -20.4% (95% CI, -23.5% to -17.5%) in the Micro-Stent group and -10.1% (95% CI, -13.9% to -6.3%) in the control group. No statistically significant between-group changes from baseline in cellular morphology were observed. Nine adverse events were possibly related to ECL, including 3 eyes with transient focal corneal edema and 4 eyes that required Micro-Stent trimming due to protrusion.

CONCLUSIONS

In eyes with OAG, ECL after phacoemulsification is acute and stabilizes after 3 months, whereas ECL after phacoemulsification plus Micro-Stent implantation proceeds for at least 5 years. Clinical findings associated with ECL in these eyes were uncommon (3.3% of implanted eyes), suggesting that ECL is generally a subclinical phenomenon.

The Quest for the Holy Grail of Glaucoma Surgery: Does Cypass Herald the End?

How to cite this article: Bhartiya S, Shaarawy T. The Quest for the Holy Grail of Glaucoma Surgery: Does Cypass Herald the End?. J Curr Glaucoma Pract 2018;12(3):99-101.

Changes in symmetry of anterior chamber following routine cataract surgery in non-glaucomatous eyes

Background

To assess minimum and maximum changes in anterior chamber dimensions following routine cataract surgery in non-glaucomatous eyes.

Methods

Forty-two eyes (42 participants) underwent routine cataract surgery with same surgeon and were assessed preoperatively, 1, 3, 6 and 12 months postoperatively. Primary outcome measure: Angle-to-angle diameter (AAD) (at 0-180^o, 45-225^o, 90-270^o, 135-315^o), Anterior-chamber-angle (ACA) (at 0^o, 45^o, 90^o, 135^o, 180^o, 225^o, 270^o and 315^o) and central anterior chamber depth (ACD) at all visits. Secondary outcome measures: relationship to axial length (AL).

Results

The mean AAD and ACA increased post-operatively in all meridians at all visits postoperatively. At 12 months, there was a maximum change in AAD in horizontal meridian (506.55 ± 468.71 μm) and least in vertical meridian (256.31 ± 1082.3 μm). The mean percentage increase in ACA postoperatively was least at 90^o (5% increase compared to 29–35% elsewhere). Central ACD deepened at all postoperative visits and this did not change over 12 months. There was no correlation between AAD, ACA and ACD with AL at any visit.

Conclusion

The AAD, ACA and ACD increases following cataract surgery in non-glaucomatous eyes, but at 12 months increase in AAD is least in vertical compared to horizontal meridian. Also, ACA was narrower (only 5% increase) superiorly compared to elsewhere (29–35% increase in ACA). This may have implications with regards to surgeries performed in the anterior chamber and corneal endothelial cell loss.

Long-term Follow-up of Ahmed Glaucoma Valve Tube Position Changes

PURPOSE

To evaluate long-term (4.5 to 6 y) changes in the position of Ahmed glaucoma valve (AGV) tubes.

MATERIALS AND METHODS

Adult patients aged 18 years and above, 1 to 2 months post-AGV implantation were enrolled. Tube position was evaluated using anterior segment optical coherence tomography at baseline and final follow-up. The intracameral tube length (ICL), tube-cornea (TC) distance, and cornea-tube angle were measured. Wilcoxon-signed rank test was used to assess whether the changes in parameters from baseline were significant.

RESULTS

In total, 11 eyes of 9 patients were included in the analysis. Mean duration of follow-up was 5.2±0.8 years (4.4 to 6.1 y). The ICL increased from 1.58±0.40 to 1.74±0.62 mm (P=0.18). The TC decreased from 0.36±0.12 to 0.29±0.05 mm (P=0.04). The cornea-tube angle decreased from 27.76±5.57 to 24.82±5.69 degrees (P=0.08). Overall, 73% of the tubes moved toward the cornea (mean 0.11 mm, over 4.4 to 6.1 y). In total, 73% showed an increase in ICL; 45% showed an increase of >0.3 mm [mean 0.50 mm (33%) increase]. Two of 11 tubes (18%) showed no significant change in the parameters (ICL, 0.03 and 0.01 mm increase; TC, 0 and 0.01 mm increase); these tubes were noted to lie on the iris.

CONCLUSIONS

Tubes tend to move toward the cornea over time. To avoid corneal damage and involvement of the visual axis in the future, tubes should be reasonably short and inserted tangentially, preferably in the posterior one third of the anterior chamber.

Laminar drainage implant

OBJECTIVE

To assess the feasibility of a novel surgical technique in painful blind eyes.

DESIGN

A prospective safety study conducted at the Federal University of Minas Gerais, Brazil.

PARTICIPANTS/SAMPLES

A total of 15 end-stage glaucomatous eyes without light perception vision.

METHODS

After implantation, conjunctival hyperemia, discharge, erosion, aqueous humor leakage, corneal edema, hyphema, anterior chamber cells and depth, dislocation of the implant, and filtering bleb height were assessed by slit-lamp biomicroscopy. Intraocular pressure was measured preoperatively and 24 months following surgery. A numerical rating scale was used to evaluate pain. Anterior segment optical coherence tomography was also assessed.

RESULTS

Laminar drainage implant surgery was performed in all patients without major complications. Mean intraocular pressure was significantly reduced after surgery without hypotensive medication (preoperatively 54.5 ± 5.1 mmHg vs 24 months after surgery 37.0 ± 15.4 mmHg, p = 0.003). Subjective ocular pain intensity also reduced (preoperatively 10 vs at 24-month follow-up visits 0). Corneal edema incidence reduced from 85.7% (95% confidence interval: 57.2%-98.2%) to 16.7% (95% confidence interval: 2.1%-48.4%) at the 24-month follow-up. No patients experienced a prolonged flat anterior chamber or erosion of overlying tissues.

CONCLUSION

The surgery was feasible and safe in painful blind eyes.

Prospective cohort study of corneal endothelial cell loss after Baerveldt glaucoma implantation

Purpose

To evaluate corneal endothelial cell loss after Baerveldt glaucoma implantation.

Methods

We prospectively evaluated changes in endothelial cell density (ECD) in the cornea of 59 patients (59 eyes) who underwent Baerveldt glaucoma implantation. Tubes were inserted into the anterior chamber in 45 eyes and pars plana in 14 eyes. The primary outcome measure was the change in corneal ECD after Baerveldt glaucoma implantation. Secondary outcome measures included relationships between corneal ECD and optical coherence tomography images of tube parameters (tube–cornea distance and tube–cornea angle) and prognostic factors for corneal ECD loss.

Results

Corneal ECD decreased significantly by 9.2% at 12 months after surgery (P = 0.001). In the anterior chamber Baerveldt glaucoma implantation group, corneal ECD at the tube insertion quadrant decreased significantly by 9.6% at 3 months (P = <0.001), 10.7% at 6 months (P = <0.001), and 13.1% at 12 months (P = <0.001). Corneal ECD at the center decreased significantly at 6 months after surgery (7.2% loss; P = 0.012) and at 12 months after surgery (12.1% loss; P = 0.001). Corneal ECD at the contralateral quadrant decreased significantly at 12 months after surgery only (10.3% loss; P = 0.004). In the pars plana Baerveldt glaucoma implantation group, no significant loss of corneal ECD was found in any corneal areas at any post-surgery follow-up visits. Tube-cornea angle was negatively correlated with the rate of corneal ECD loss at the tube insertion quadrant; r = −0.55 (P = 0.0013). In multivariable analyses, exfoliation glaucoma and narrower tube–cornea angle were significant prognostic factors for severe corneal ECD loss (P = 0.0068 and P = 0.046, respectively).

Conclusions

Anterior chamber Baerveldt glaucoma implantation causes corneal endothelial cell loss. Corneal endothelial cell loss starts at the tube insertion quadrant. Exfoliation glaucoma and narrower tube-corneal angle are associated with severe loss of corneal endothelial cells.

Effectiveness and safety of sulcus fixation of Baerveldt glaucoma implants in glaucomatous eyes in patients who underwent multiple intraocular surgeries

PURPOSE

The purpose of this study was to evaluate the surgical success of sulcus fixation of Baerveldt glaucoma implant (BGIs) in special reference to corneal damage.

METHODS

This observational prospective cohort study included 24 patients who underwent a median of 3.0 previous intraocular surgeries and sulcus fixation of BGIs for the first time. The intraocular pressure (IOP), the number of ocular hypotensives used, corneal endothelial cell density (ECD), and logMAR-converted best-corrected visual acuity (VA) of each patient were measured preoperatively and postoperatively until 12 months after surgery. Surgical success was evaluated after 12 months based on the reduction of IOP (5-21 mmHg and > 20% reduction), corneal damage (postoperative development of decompensation, unmeasurable ECD, or ECD reduction of > 20%), loss of light perception, and need for additional surgeries.

RESULTS

Surgical success was noted in 16 (66.7%) patients when corneal damage was included as a failure criterion, whereas surgery was successful in 21 (87.5%) patients when solely judged using IOP control similarly as previous clinical trials. The median IOP decreased from 27.5 mmHg preoperatively to 14.5 mmHg postoperatively (P < 0.0001). The number of ocular hypotensives was significantly reduced postoperatively (P < 0.0001). The median postoperative ECD reduction was only 0.15%, although ECD could not be measured during follow-up or it was significantly reduced by > 20% in six patients. VA was not significantly reduced after surgery. Adverse effects were observed in 15 patients (62.5 cumulative %).

CONCLUSION

Sulcus fixation of BGIs may be effective and safe in patients with glaucomatous eyes who underwent multiple prior intraocular surgeries.

Glaucoma-associated corneal endothelial cell damage: A review

The corneal endothelium is critical in maintaining a healthy and clear cornea. Corneal endothelial cells have a significant reserve function, but preservation of these cells is paramount as they have limited regenerative capacity. Glaucoma is a prevalent disease, and damage to the corneal endothelium may be caused by the disease process itself as well as by its treatment. The mechanisms involved in glaucoma-associated damage to the corneal endothelium need further investigation. Understanding how glaucoma and glaucoma surgery impact the endothelium is important for protecting corneal clarity and visual acuity in all glaucoma patients, including those undergoing corneal transplant. We will discuss a range of identified factors that may impact corneal endothelial cell health in glaucoma, including intraocular pressure, glaucoma medications, surgical glaucoma management, mechanical forces, and alterations in the aqueous environment.

Corneal endothelial cell loss after Baerveldt glaucoma drainage device implantation in the anterior chamber

Purpose

To investigate central and peripheral corneal endothelial cell density (ECD) in relation to Baerveldt (BV) glaucoma drainage device (GDD) tube corneal (TC) distance.

Methods

Prospective study of all patients scheduled for glaucoma tube surgery with 36 months follow‐up. A BV GDD was inserted into the anterior chamber (AC). Anterior segment optical coherence tomography (AS‐OCT) scans were made to determine the TC distance. Central and peripheral ECD was measured, preoperatively and at 3, 6, 12, 24 and 36 months postoperatively.

Results

Fifty‐three eyes were included [primary open‐angle glaucoma, (n = 13); secondary glaucoma, (n = 30); and primary angle‐closure glaucoma, (n = 10)]. Central ECD significantly decreased during follow‐up, with a mean decrease of 4.54% per year (p < 0.001), and 6.57% in the peripheral quadrant closest to the BV GDD tube (PQC, p < 0.001). In the PQC, a yearly decrease of 1.57% was shown after transiridial tube placement versus 7.43% after placement ‘free’ into the AC (p = 0.006). Endothelial cell (EC) loss was related to TC distance (mean 1.69 mm), with a central loss of 6.20% and 7.25% in the PQC per year with shorter TC distances, versus a central loss of 4.11% and 5.77% in the PQC per year with longer TC distances (outside mean ± 2SD, p < 0.001). A difference in EC loss by glaucoma subtype was not identified.

Conclusion

The TC distance is of significant influence on corneal ECD, a shorter TC distance causing more severe EC loss, especially in the PQC. Transiridial placement of the BV GDD tube seems safer than placement ‘free’ into the AC.

Postoperative Complications in the Ahmed Baerveldt Comparison Study During Five Years of Follow-up

PURPOSE

To compare the late complications in the Ahmed Baerveldt Comparison Study during 5 years of follow-up.

DESIGN

Multicenter, prospective randomized clinical trial.

METHODS

setting: Sixteen international clinical centers.

STUDY POPULATION

Two hundred seventy-six subjects aged 18-85 years with previous intraocular surgery or refractory glaucoma with intraocular pressure of >18 mm Hg.

INTERVENTIONS

Ahmed Glaucoma Valve FP7 or Baerveldt Glaucoma Implant BG 101-350.

MAIN OUTCOME MEASURES

Late postoperative complications (beyond 3 months), reoperations for complications, and decreased vision from complications.

RESULTS

Late complications developed in 56 subjects (46.8 ± 4.8 5-year cumulative % ± SE) in the Ahmed Glaucoma Valve group and 67 (56.3 ± 4.7 5-year cumulative % ± SE) in the Baerveldt Glaucoma Implant group (P = .082). The cumulative rates of serious complications were 15.9% and 24.7% in the Ahmed Glaucoma Valve and Baerveldt Glaucoma Implant groups, respectively (P = .034), although this was largely driven by subjects who had tube occlusions in the 2 groups (0.8% in the Ahmed Glaucoma Valve group and 5.7% in the Baerveldt Glaucoma Implant group, P = .037). Both groups had a relatively high incidence of persistent diplopia (12%) and corneal edema (20%), although half of the corneal edema cases were likely due to pre-existing causes other than the aqueous shunt. The incidence of tube erosion was 1% and 3% in the Ahmed Glaucoma Valve and Baerveldt Glaucoma Implant groups, respectively (P = .04).

CONCLUSIONS

Long-term rates of vision-threatening complications and complications resulting in reoperation were higher in the Baerveldt Glaucoma Implant than in the Ahmed Glaucoma Valve group over 5 years of follow-up.

Glaucoma surgery: taking the sub-conjunctival route

We are currently in the midst of a surge in interest in glaucoma surgery. Novel pathways for reducing intraocular pressure (IOP) have been tried with various levels of success over the last few years. While the trabecular bypass and suprachoroidal approaches have captured much of the attention, filtering aqueous into the sub-conjunctival space remains the gold standard for lowering IOP. This review attempts to focus on current research in surgical methods to enhance filtration by potentially improving on tried and tested methods like the trabeculectomy, deep sclerectomy, and tube surgeries.

Comparison of the changes in corneal endothelial cells after pars plana and anterior chamber ahmed valve implant

Purpose. To compare the changes in corneal endothelial cells after pars plana Ahmed glaucoma valve (AGV) implantation with those after the anterior chamber AGV implantation for refractory glaucoma. Methods. The medical records of 18 eyes with pars plana implantation of AGV (ppAGV) were reviewed retrospectively and were compared with 18 eyes with the anterior chamber AGV (acAGV) implant. The preoperative and postoperative endothelial cells, intraocular pressure (IOP), and postoperative complications during the follow-up in both groups were compared. Results. The average follow-up was 18 months. The postoperative endothelial cells in the ppAGV and acAGV groups were 2044 ± 303 and 1904 ± 324, respectively (P = 0.25). The average percentage decrease in the endothelial cells in the ppAGV and acAGV groups at 18 months was 12.5% and 18.4%, respectively, and showed significant difference between the 2 groups (P = 0.01). No difference in IOP control and the number of postoperative glaucoma medications was observed between the 2 groups. Conclusions. Endothelial cell damage in the ppAGV group for refractory glaucoma appeared to be lower than that in the acAGV group. Therefore, pars plana implantation of AGV may be preferred as it may have lower level of endothelial cell damage while maintaining similar level of IOP control.

Outcomes of glaucoma reoperations in the Tube Versus Trabeculectomy (TVT) Study

PURPOSE

To describe the incidence and outcomes of reoperations for glaucoma in the Tube Versus Trabeculectomy (TVT) Study.

DESIGN

Cohort study of patients in a multicenter randomized clinical trial.

METHODS

The TVT Study enrolled 212 patients with medically uncontrolled glaucoma who had previous cataract and/or glaucoma surgery. Randomization assigned 107 patients to surgery with a tube shunt (350 mm(2) Baerveldt glaucoma implant) and 105 patients to trabeculectomy with mitomycin C (0.4 mg/mL for 4 minutes). Data were analyzed from patients who failed their assigned treatment and had additional glaucoma surgery. Outcome measures included intraocular pressure (IOP), use of glaucoma medications, visual acuity, surgical complications, and failure (IOP >21 mm Hg or not reduced by 20%, IOP ≤5 mm Hg, additional glaucoma surgery, or loss of light perception vision).

RESULTS

Additional glaucoma surgery was performed in 8 patients in the tube group and 18 patients in the trabeculectomy group in the TVT Study, and the 5-year cumulative reoperation rate was 9% in the tube group and 29% in the trabeculectomy group (P = .025). Follow-up (mean ± SD) after additional glaucoma surgery was 28.0 ± 16.0 months in the tube group and 30.5 ± 20.4 months in the trabeculectomy group (P = .76). At 2 years after a glaucoma reoperation, IOP (mean ± SD) was 15.0 ± 5.5 mm Hg in the tube group and 14.4 ± 6.6 mm Hg in the trabeculectomy group (P = .84). The number of glaucoma medications (mean ± SD) after 2 years of follow-up was 1.1 ± 1.3 in the tube group and 1.4 ± 1.4 in the trabeculectomy group (P = .71). The cumulative probability of failure at 1, 2, 3, and 4 years after additional glaucoma surgery was 0%, 43%, 43%, and 43%, respectively, in the tube group, and 0%, 9%, 20%, and 47% in the trabeculectomy group (P = .28). Reoperations to manage complications were required in 1 patient in the tube group and 5 patients in the trabeculectomy group (P = .63).

CONCLUSIONS

The rate of reoperation for glaucoma was higher following trabeculectomy with mitomycin C than tube shunt surgery in the TVT Study. Similar surgical outcomes were observed after additional glaucoma surgery, irrespective of initial randomized treatment in the study.

Baerveldt drainage tube motility in the anterior chamber

PURPOSE

To investigate the stability in position of the Baerveldt glaucoma drainage tube over time and to study movement of the drainage tube in the anterior chamber (AC) under varying light conditions.

METHODS

This prospective study included 70 eyes with implantation of a Baerveldt glaucoma drainage tube in the anterior chamber. Anterior segment optical coherence tomography (AS-OCT) images were made preoperatively to quantify AC depth. AS-OCT images were made twice under photopic and twice under scotopic conditions, in the angle parallel to the Baerveldt tube to quantify drainage tube position, at 3, 6, 12, and 24 months postoperatively. Tube-corneal (T-C) and tube-iris (T-I) distances were measured. Additionally, the central AC depth and the peripheral angle opening (AOD 500) were determined. Two subgroups were distinguished according to tube position: free in the AC (group 1, n = 48) and transiridal (group 2, n = 22).

RESULTS

After 24 months of follow-up, the drainage tube was found to move statistically significantly closer (0.12 mm) to the corneal endothelium in group 1 (p<0.01). There was no statistically significant difference in T-C distance over time in group 2. The T-C distance did not differ under photopic versus scotopic circumstances (p = 0.32). In both groups, the T-I distance was larger under scotopic conditions, a result of pupil dilation.

CONCLUSIONS

The Baerveldt glaucoma drainage tube remained in a stable position when a transiridal implantation was performed, whereas the tube moved closer to the endothelium when placed free into the AC. Transiridal implantation of the Baerveldt tube seems a safe alternative for tube implantation with respect to tube motility.

Application of anterior segment optical coherence tomography in glaucoma

Optical coherence tomography (OCT) is a cross-sectional, three-dimensional, high-resolution imaging modality that uses low coherence interferometry to achieve axial resolution in the range of 3-20 μm. Two OCT platforms have been developed: time domain (TD-OCT) and spectral (or Fourier) domain (SD/FD-OCT). Visante anterior segment OCT (Carl Zeiss Meditec) is a TD-OCT widely used for anterior segment imaging. The SD-OCT systems with both posterior and anterior segment imaging capabilities include the RTVue, iVue (Optovue), the Cirrus (Carl Zeiss Meditec), and the Spectralis (Heidelberg Engineering, Inc.). Each of the SD-OCTs has a wavelength in the range of 820-879 nm. Anterior segment OCT is a non-contact method providing high resolution tomographic cross-sectional imaging of anterior segment structures. Anterior segment OCT provides qualitative and quantitative assessment of the anterior segment structures important to the pathogenesis and the anatomical variations of glaucoma, and the approach to and success of treatment. We summarize the clinical applications of anterior segment OCT in glaucoma.

Study of anterior chamber aqueous tube shunt by fourier-domain optical coherence tomography

Purpose. This cross-sectional, observational study used Fourier-domain optical coherence tomography (OCT) to examine the position, patency, and the interior entrance site of anterior chamber (AC) aqueous tube shunts. Methods. The OCT, slitlamp biomicroscopy, and gonioscopy findings of 23 eyes of 18 patients with AC shunts were collected and compared. Results. OCT images demonstrated the shunt position and patency in all 23 eyes, and the details of the AC entrance in 16 eyes. The position of the tube varied, with the majority (14/23) on the surface of the iris. The exact position of the AC entrance relative to Schwalbe's line (SL) could be determined in 9 eyes (posterior to SL in 7 eyes, anterior in 2 eyes). At the AC entrance, growth of fibrous scar tissue was present between the tube and the corneal endothelium in all 16 eyes in which the entrance could be clearly visualized. It's a new finding that could not be visualized by slitlamp examination or lower resolution OCT. Conclusion. Compared to slitlamp examination, Fourier-domain OCT of AC tube shunts provided more detailed anatomic information regarding the insertion level relative to SL, scar tissue between the tube and the corneal endothelium, and patency of the tube opening.

Serial intracameral visualization of the Ahmed glaucoma valve tube by anterior segment optical coherence tomography

PURPOSE

To investigate serial changes of the Ahmed glaucoma valve (AGV) implant tube in the anterior chamber by anterior segment optical coherence tomography (AS-OCT).

METHODS

Patients who had received AGV implantation without complications (n=48) were included in this study. Each patient received follow-up examinations including AS-OCT at days 1 and 2, week 1, and months 1, 3, 6, and 12. Tube parameters were defined to measure its length and position. The intracameral length of the tube was from the tip of the bevel-edged tube to the sclerolimbal junction. The distance between the extremity of the tube and the anterior iris surface (T-I distance), and the angle between the tube and the posterior endothelial surface of the cornea (T-C angle) were defined. Factors that were related to tube parameters were analysed by multiple regression analysis.

RESULTS

The mean change in tube length was -0.20 ± 0.17 mm, indicating that the tube length shortened from the initial inserted length. The mean T-I distance change was 0.11 ± 0.07 mm and the mean T-C angle change was -6.7 ± 5.6°. Uveitic glaucoma and glaucoma following penetrating keratoplasty showed the most changes in tube parameters. By multiple regression analysis, diagnosis of glaucoma including uveitic glaucoma (P=0.049) and glaucoma following penetrating keratoplasty (P=0.008) were related to the change of intracameral tube length.

CONCLUSIONS

These results suggest that the length and position of the AGV tube changes after surgery. The change was prominent in uveitic glaucoma and glaucoma following penetrating keratoplasty.

Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up

PURPOSE

To describe postoperative complications encountered in the Tube Versus Trabeculectomy (TVT) Study during 5 years of follow-up.

DESIGN

Multicenter randomized clinical trial.

METHODS

SETTINGS

Seventeen clinical centers.

STUDY POPULATION

Patients 18 to 85 years of age who had previous trabeculectomy and/or cataract extraction with intraocular lens implantation and uncontrolled glaucoma with intraocular pressure (IOP) ≥18 mm Hg and ≤40 mm Hg on maximum tolerated medical therapy.

INTERVENTIONS

Tube shunt (350-mm(2) Baerveldt glaucoma implant) or trabeculectomy with mitomycin C (MMC 0.4 mg/mL for 4 minutes).

MAIN OUTCOME MEASURES

Surgical complications, reoperations for complications, visual acuity, and cataract progression.

RESULTS

Early postoperative complications occurred in 22 patients (21%) in the tube group and 39 patients (37%) in the trabeculectomy group (P = .012). Late postoperative complications developed in 36 patients (34%) in the tube group and 38 patients (36%) in the trabeculectomy group during 5 years of follow-up (P = .81). The rate of reoperation for complications was 22% in the tube group and 18% in the trabeculectomy group (P = .29). Cataract extraction was performed in 13 phakic eyes (54%) in the tube group and 9 phakic eyes (43%) in the trabeculectomy group (P = .43).

CONCLUSIONS

A large number of surgical complications were observed in the TVT Study, but most were transient and self-limited. The incidence of early postoperative complications was higher following trabeculectomy with MMC than tube shunt surgery. The rates of late postoperative complications, reoperation for complications, and cataract extraction were similar with both surgical procedures after 5 years of follow-up.

Update on aqueous shunts

Medicare claims data and surveys of the American Glaucoma Society membership show that aqueous shunts are being increasingly utilized in the surgical management of glaucoma. New clinical trials data have identified differences in the efficacy and safety of shunts in common use. Recent studies have reported comparable results with trabeculectomy and aqueous shunts in similar patient groups. Intraoperative and postoperative complications may develop with aqueous shunt surgery related to the implantation of a foreign material. Several modifications in surgical technique have been directed toward improving surgical success, reducing complications, and optimizing efficiency and cost.

Corneal endothelial morphology in eyes implanted with anterior chamber aqueous shunts

PURPOSE

To investigate risk factors for lower corneal endothelial cell density after anterior chamber aqueous shunt implantation.

METHODS

Forty eyes implanted with aqueous shunts were examined using anterior segment optical coherence tomography to document shunt position and specular microscopy for central corneal endothelial cell density (CCED) and peripheral (in the vicinity of the tube) corneal endothelial cell density (PCED). Other clinical parameters relating to shunt implantation were also recorded and analyzed.

RESULTS

Mean CCED and PCED were 1537 ± 681 cells per square millimeter and 1310 ± 586 cells per square millimeter. The median follow-up was 36 months (range: 24-72 months) after shunt implantation. There was a significant association among the time from shunt implantation (β coefficient = -0.325; P = 0.040), the degree of peripheral anterior synechiae (PAS) in clock hours (β = -0.439; P = 0.004), and the number of previous operations (β = -0.316; P = 0.047) with CCED, whereas the degree of PAS was the only factor associated with PCED (β = -0.391; P = 0.013) on univariate analysis. Multiple linear regression analysis revealed that the degree of PAS was the only factor associated with CCED (β = -0.351; P = 0.023). There was no correlation between shunt position parameters and corneal cell density.

CONCLUSIONS

The association between lower corneal cell density and aqueous shunt implantation appeared to be multifactorial, with the degree of PAS to be the most significant. Anterior segment optical coherence tomography is a promising technique for quantifying tube position in the anterior chamber after aqueous shunt implantation.

Value of optical coherence tomography for anterior segment surgery

Anterior segment optical coherence tomography (AS-OCT) is an important new noncontact imaging technology that uses a 1310 nm super luminescent diode. It can be used to assess anterior chamber biometry, corneal thickness, lens thickness, and angle configuration; to visualize pathological processes; to evaluate postsurgical anatomy and posttraumatic eyes; and to image phakic intraocular lenses and intracorneal ring segments. Because it is a noncontact technique, it can also be used intraoperatively, which could be useful during trabeculectomy and after deep anterior lamellar keratoplasty to detect abnormalities in the cornea and interface. A disadvantage of AS-OCT is its inability to penetrate the iris pigment epithelium, which makes it impossible to evaluate the structures behind the iris. The most frequently used devices are time-domain AS-OCT, but new Fourier-domain OCT devices, which have faster image acquisition and higher resolution, are currently under investigation.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Graft failure after penetrating keratoplasty in eyes with Ahmed valves

PURPOSE

To determine incidence and risk factors for graft failure following penetrating keratoplasty (PK) in eyes with Ahmed valves (AV).

DESIGN

Retrospective, observational cohort study.

METHODS

Patients who underwent PK after AV implantation (both performed at our institution through 2004) were studied. Intervals to graft failure (defined as either dysfunction [stromal thickening with retention of clarity] or decompensation [central microcystic edema or loss of clarity]) were analyzed using Kaplan-Meier technique. Risk factors for graft failure were analyzed using Cox proportional hazard models.

RESULTS

Included were 77 eyes (77 patients; first procedure 1993). Following PK, 40 eyes (52%) required increased numbers of glaucoma medications; 10 eyes (13%) required additional glaucoma drainage device(s). Graft failure at 1, 2, and 3 years was 42.4% (95% confidence interval: 32.0%-54.6%), 57.1% (45.6%-69.1%), and 59.1% (47.5%-71.2%), respectively. Prior PK (HR 2.38, P = .006) and stromal vessels (HR 2.90, P = .0005) were associated with increased risk of graft failure. Use of glaucoma medications (HR 0.27, P = .009) and evidence of lower intraocular pressures (IOP) during follow-up (excluding hypotony; HR 0.92, P = .010) were associated with reduced risk of graft failure. Endothelial rejection episodes were observed in 13 eyes (17%); however, rejection was not a risk factor for graft failure (P = .98).

CONCLUSIONS

Long-term survival of corneal grafts is poor in eyes with AV. The majority of graft failures are associated with progressive loss of endothelial function, without observed immunologic rejection. Despite the presence of an AV, escalation in glaucoma therapy often follows PK; graft failure may be related to poor IOP control.