Changes in corneal endothelial cell density and the cumulative risk of corneal decompensation after Ahmed glaucoma valve implantation

Corneal endothelial density loss in patients after gonioscopy‑assisted transluminal trabeculotomy

PURPOSE

To compare short-term changes in corneal endothelial cells after gonioscopy-assisted transluminal trabeculotomy(GATT).

METHODS

This retrospective comparative study included 138 patients(138 eyes), and 98 of these patients underwent GATT procedure and 40 underwent SLT procedure as a control group. Changes in the corneal endothelium in patients who underwent GATT and SLT were analyzed retrospectively. Endothelial changes in the central cornea were examined using specular microscopy before and 6 months after the GATT and SLT procedure. Intraocular pressure(IOP), number of glaucoma medications, and side effects were evaluated at visits before and after two methods.

RESULTS

One hundred and thirty-eight eyes of 138 patients with a mean age of 62.9±12.7 years in the SLT group and 62.5±11.8 years in the GATT group were included in this study. Pre-procedure mean ± SD IOP was 27.7±3.6 mmHg and 27.4±5.3 mmHg (p=0.173) 2.8±0.5 and 2.9±0.8 (p=0.204) glaucoma drugs are in the SLT and GATT group, respectively. The mean corneal endothelial cell density (CECD) in the SLT group was 2433.1±581.4 cells/mm2 before the procedure and 2435.1±585 cells/mm2 6 months after the procedure, a change of 0.1±0.6% which was not statistically significant (p>0.967).The mean CECD at baseline in the GATT group was 2443.4±508.2 cells/mm2 and decreased to 2290.2±527.7 cells/mm2 6 months after this procedure, representing a cell loss of 6,2±9,1% (p<0.001).

CONCLUSION

GATT caused more CECD damage than SLT at the sixth month after the procedure. Considering the loss of CECD in candidates for GATT, sufficient number of endothelial cells in the central cornea is recommended.

Glaucoma Drainage Device Implantation, Outcomes, and Complications

Glaucoma drainage device (GDD) surgery has gained popularity as a treatment strategy for patients with medically uncontrolled glaucoma. Glaucoma is the leading cause of irreversible blindness in the world and continues to be a major public health issue. While our understanding of glaucoma continues to evolve, the primary treatment for glaucoma continues to be intraocular pressure (IOP) control. When medical treatment fails, glaucoma surgery is considered. GDD implantation is one of the most commonly performed incisional glaucoma surgeries. GDD was originally designed for patients with secondary glaucoma and/or patients who are at an increased risk of failure after trabeculectomy. More recently, its application has been extended to primary glaucoma as the first choice of incisional surgery. This manuscript summarizes recent GDD types, implantation, clinical outcome and complications.

Different patterns in the corneal endothelial cell loss after pars plana and pars limbal insertion of the Baerveldt glaucoma implant

PURPOSE

To assess corneal endothelial cell (CE) loss after pars plana (PP) and pars limbal (PL) insertion of a Baerveldt glaucoma implant (BGI).

DESIGN

Retrospective multicenter interventional comparative study.

METHODS

We studied central CE loss for 5 years after BGI surgery in 192 eyes.

RESULTS

The prevalence of bullous keratopathy (BK) was greater in the PL cohort than in the PP cohort (P = .003). The CE loss after simultaneous PP vitrectomy and tube insertion into the vitreous cavity was 11.9% in the first year, which was greater than that of 2.9% in eyes where the tube was inserted simply into the vitreous cavity after a prior vitrectomy (P = .046). The annual percentage CE loss after the first year decreased unidirectionally in both of those groups and was 1.3% and 1.0% in the fifth year, respectively (P < .001). For limbal insertion, the CE loss in the simple PL cohort was biphasic, decreasing from 10.5% in the first year to 7.0% in the fifth year. Simultaneous cataract and BGI surgery enhanced the CE loss slightly in the first year in the PP and PL cohorts to 13.0% and 14.0%, respectively. However, these increases were not significant (P = .816 and .358, respectively). Low preoperative CE density (P < .001) and insertion site (P = .020) were significant risk factors for the development of BK.

CONCLUSIONS

CE loss in the PL and PP cohorts was biphasic and unidirectional, respectively. The difference in annual CE loss became evident over time. PP tube implantation may be advantageous when the preoperative CE density is low.

Surgical Augmentation of the Suprachoroidal Space: A Novel Material and Implant

Microinvasive glaucoma surgery (MIGS) has emerged as a safer method to lower IOP with minimal impact on patient quality of life compared to traditional glaucoma surgeries. With the advent of MIGS, there has been a renewed interest in exploring the suprachoroidal route. MIGS targeting the suprachoroidal space allow for a safe reduction in IOP while sparing conjunctiva and allowing "blebless" surgery, thus avoiding bleb-related complications. This article aims to review the rationale behind the suprachoroidal MIGS procedures and the literature surrounding the efficacy and safety of a novel suprachoroidal device, the MINIject. The available literature has shown promising IOP lowering results with the MINIject implant with a potentially safer and less invasive approach than traditional glaucoma surgeries.

Effect of guided Ahmed glaucoma valve implantation on corneal endothelial cells: A 2-year comparative study

PURPOSE

To compare the effects of guided and non-guided Ahmed glaucoma valve (AGV) implantation on the corneal endothelium.

METHODS

Medical records of patients who underwent AGV implantation in the anterior chamber (AC) were reviewed retrospectively. The eyes were divided into two groups depending on the use of a guidance technique with spatula and a 4-0 nylon intraluminal stent. Specular microscopy was performed to measure corneal endothelial cell density (ECD) loss after surgery, and the rate of ECD change was calculated. Tube parameters were measured using anterior segment optical coherence tomography (AS-OCT).

RESULTS

The ECD loss during 2 years of follow-up was significantly lower in the guided AGV implantation (gAGV) group than in the non-guided implantation (ngAGV) group, and the rate of ECD change was -0.62 ± 1.23 and -1.42 ± 1.57%/month in the gAGV and ngAGV groups, respectively (p = 0.003). The mean tube-cornea distance (TCD) and mean tube-cornea angle (TCA) were significantly greater in the gAGV group than in the ngAGV group. The frequency of tube repositioning within 2 years after surgery was 0% in the gAGV group and 12.66% in the ngAGV group (p = 0.005).

CONCLUSIONS

The use of a guidance technique can reduce corneal endothelial loss during the first 2 years after AGV implantation in the AC. The tube was positioned at a more distant and wider angle from the cornea in the eyes of the gAGV group, which may have contributed to the reduced need for tube repositioning to prevent corneal decompensation.

A Comprehensive Review of Pediatric Glaucoma Following Cataract Surgery and Progress in Treatment

Glaucoma following cataract surgery (GFCS) remains a serious postoperative complication of pediatric cataract surgery. Various risk factors, including age at lensectomy, intraocular lens implantation, posterior capsule status, associated ocular/systemic anomaly, additional intraocular surgery, and a family history of congenital cataract and GFCS, have been reported. However, the optimal surgical approach remains unclear. This review evaluates the diagnostic criteria, classification, risk factors, mechanism, and surgical management, especially the efficacy of minimally invasive glaucoma surgery, in GFCS, and aims to propose an optimal clinical management strategy for GFCS. The results of our review indicate that ab interno trabeculotomy (goniotomy) may be the most appropriate first-line treatment for GFCS.

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.

Survey of the American Glaucoma Society Membership on Current Glaucoma Drainage Device Placement and Postoperative Corticosteroid Use

Purpose

To assess practice patterns and opinions of glaucoma specialists regarding glaucoma drainage device tube shunt placement and post-operative anti-inflammatory medication use. We also assess the perceived need for a randomized control trial to compare them.

Patients and Methods

An online survey was distributed to a group of glaucoma specialists from the American Glaucoma Society via the American Glaucoma Society forum from April to August 2021.

Results

One hundred and twenty-eight responses were included. Ninety percent placed tubes in the anterior chamber. Sixty-one percent reported that evidence suggested the superiority of sulcus tube placement over the anterior chamber, whereas 34% reported there was not enough evidence to suggest superiority of either in preventing endothelial cell loss. Comparing these techniques for intraocular pressure control, 49% reported evidence suggested sulcus tube placement superiority whereas 46% reported there was not enough evidence. Over 40% of respondents reported that they were either unfamiliar with literature or that there was not enough evidence to support the superiority of difluprednate 0.05% over prednisolone 1% for post-operative use in preventing endothelial cell loss and for intraocular pressure control. Ninety percent and 81% of respondents respectively would benefit from randomized control trials comparing outcomes of anterior chamber vs sulcus tube placement and post-operative corticosteroid usage.

Conclusion

Most glaucoma specialists surveyed place glaucoma drainage device tube in the anterior chamber over the sulcus. A randomized control trial to determine optimal tube placement and post-operative anti-inflammatory medication use for preventing endothelial cell loss would change current glaucoma drainage device practice patterns.

Corneal Edema and Keratoplasty: Risk Factors in Eyes With Previous Glaucoma Drainage Devices

PURPOSE

To assess risk factors contributing to corneal decompensation following glaucoma drainage device (GDD) implantation.

DESIGN

Retrospective case control study.

METHODS

Records of 1610 eyes that underwent GDD implantation between June 1, 2009, and April 1, 2020, at the Johns Hopkins Wilmer Eye Institute were reviewed. Seventy-nine eyes (5%) developed corneal decompensation, of which 46 underwent keratoplasty. These 79 cases were matched with 220 controls. Cox proportional hazard models with robust standard error estimates to account for clustering at the matched-pair level were used to assess risk factors for corneal decompensation. Kaplan-Meier survival analysis analyzed time to corneal decompensation.

RESULTS

The mean (SD) age of cases and controls was 68 (12.3) and 60.5 (15.9) years, respectively. The mean time from GDD implantation to corneal decompensation was 32 months, and the cumulative probability of developing decompensation at 3, 6, and 9 years was 4.7%, 9.2%, and 14.8%, respectively. Final visual outcomes in cases were worse, with a final mean ± SD visual acuity (logMAR) of 1.96±1.25 relative to a mean±SD visual acuity of 1.11±1.36 in controls (P < .001). In the multivariable model, significant risk factors for corneal decompensation were increased age (adjusted hazard ratio [AHR] 1.39, 95% CI 1.18, 1.63; P ≤ .001), history of Fuchs dystrophy or iridocorneal endothelial syndrome (AHR 9.18, 95% CI 5.35, 15.74; P ≤ .001), and postoperative complications such as hypotony (AHR 3.25, 95% CI 1.85, 5.72; P ≤ .001) and tube-cornea touch (AHR 6.37, 95% CI 3.77, 10.75; P ≤ .001).

CONCLUSIONS

The risk of postoperative corneal decompensation is persistent over time. Patients receiving GDDs, particularly those with advanced age, preexisting corneal pathology, and postoperative complications, should be counseled regarding their increased risk for corneal decompensation.

Effect of Postoperative Trimming of the Tube Portion of Ahmed Glaucoma Valve on Corneal Endothelial Cell Loss

PRCIS

We reduced the tube length through a small limbal incision in eyes that underwent Ahmed glaucoma valve (AGV) implantation and found that the rate of corneal endothelial cell (CEC) density was markedly reduced from -12.2% per year to -3.5% per year after this simple procedure.

PURPOSE

The aim was to evaluate the effect of postoperative tube tip trimming (TT) after AGV implantation on CEC loss.

METHODS

In this retrospective cohort study, a total of 75 eyes from 67 patients (41 eyes in the AGV implantation only group (AGVG: mean follow-up, 42.2±13.8 mo) and 34 eyes in the TT after AGV implantation group (TAGVG: mean follow-up, 64.9±18.5 mo) were analyzed. TT was performed through a small limbal incision at a mean of 41 months after AGV implantation. Both groups were followed up for at least 1 year and underwent at least 2 specular microscopic examinations after AGV implantation and/or TT.

RESULTS

In the AGVG, CEC density was reduced from 2247.0±527.3 to 1665.7±643.3 cells/mm2 (P<0.001). In the TAGVG, it was reduced from 2383.1±619.4 to 1552.9±700.9 cells/mm2 before TT (mean 41 mo of follow-up) and after TT, to 1394.6±654.7 cells/mm2 (mean 26 mo of the follow-up). The reduction rate of CEC density before TT was -12.2±6.5% per year, and this rate was significantly reduced to -3.5±6.9% per year after TT in the TAGVG (P=0.002). The probability of corneal failure defined as a 15% reduction in CEC density was significantly reduced after TT in TAGVG (P=0.038).

CONCLUSIONS

Tube TT after AGV implantation markedly reduced the rate of CEC loss without serious complications in eyes with AGV implantation.

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.

[Descemet membrane endothelial keratoplasty after implantation of glaucoma drainage devices]

Secondary decompensation of corneal endothelium, including transplanted, is a frequent long-term complication of glaucoma drainage surgery. According to literature data, after implantation of a glaucoma drainage device into the anterior chamber, the speed of endothelial cells density (ECD) loss increases significantly.

PURPOSE

To study the possibility of performing modified Descemet membrane endothelial keratoplasty (DMEK) with maximum graft diameter, and to assess its short-term effectiveness in the treatment of bullous keratopathy (BK) in the presence of a glaucoma drainage device in the anterior chamber.

MATERIAL AND METHODS

Modified surgery ³/₄-DMEK was performed in 9 eyes of 7 patients with BK and Ahmed glaucoma drainage using graft of maximum diameter (11±1 mm). Average follow-up time was 15.3±2.5 months (12 to 18 months).

RESULTS

No intraoperative or postoperative complications were observed. Mean ECD after 12 months amounted to 1664±346 cells/mm², which corresponds to ECD reduction of 34±9.6% (24 to 49%) in comparison to preoperative values. Mean best corrected visual acuity 12 months after surgery increased from 0.04±0.03 (0.01 to 0.1) to 0.3±0.2 (0.04 to 0.7). The last follow-up examination revealed all corneas to have preserved transparency and stable pachymetry measurements (from 488 to 548 µm).

CONCLUSION

Performing ³/₄-DMEK with a mega graft for treatment of BK after drainage surgery is technically possible. Absence of Descemet membrane (DM) donor and preservation of DM recipient in the drainage tube plane eliminates its contact with the endothelium. Maximum graft diameter should in the long term help prolong the effectiveness of the surgery.

Graft survival of Descemet membrane endothelial keratoplasty (DMEK) in corneal endothelial decompensation after glaucoma surgery

Purpose

This study aims to assess the results, rebubbling rate, and graft survival after Descemet membrane endothelial keratoplasty (DMEK) with regard to the number and type of previous glaucoma surgeries.

Methods

This is a clinical retrospective review of 1845 consecutive DMEK surgeries between 07/2011 and 08/2017 at the Department of Ophthalmology, University of Cologne. Sixty-six eyes were included: group 1 (eyes with previous glaucoma drainage devices (GDD); n = 27) and group 2 (eyes with previous trabeculectomy (TE); n = 39). Endothelial cell loss (ECL), central corneal thickness, graft failure, rebubbling rate, and best spectacle-corrected visual acuity (BSCVA) up to 3 years after DMEK were compared between subgroups of patients with different numbers of and the two most common types of glaucoma surgeries either GDD or TE or both.

Results

Re-DMEK rate due to secondary graft failure was 55.6% (15/27) in group 1 and 35.9% in group 2. The mean graft survival time in group 1 was 25 ± 11 months and 31.3 ± 8.6 months in group 2 (p = 0.009).

ECL in surviving grafts in group 1 was 35% (n = 13) at 6 months, 36% at 12 months (n = 8), and 27% (n = 4) at 2 years postoperatively. In group 2, ECL in surviving grafts was 41% (n = 10) at 6 months, 36% (n = 9) at 12 months, and 38% (n = 8) at 2 years postoperatively. Rebubbling rate in group 1 was 18.5% (5/27) and 35.9% (14/39) in group 2 (p = 0.079).

Conclusion

Eyes with previous GDD had no higher risk for an increased rebubbling rate but a higher risk for a re-DMEK due to secondary graft failure with a mean transplant survival time of about 2 years. Compared to eyes with preexisting glaucoma drainage device, eyes after trabeculectomy had less secondary graft failures and a longer mean graft survival rate.

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.

Trends in surgical procedures and indications for corneal transplantation over 27 years in a tertiary hospital in Japan

PURPOSE

To characterize trends in procedures, and indications for corneal transplantation over 27 years in a single referral center in Japan.

STUDY DESIGN

Retrospective study.

METHODS

Data from a consecutive series of corneal transplant surgery cases performed from 1991 to 2017at Ichikawa General Hospital were collected. The surgical procedures, indications, and causes of corneal endothelial dysfunction were evaluated.

RESULTS

Among 6,025 transplantations, a total of 3,991 cases underwent penetrating keratoplasty (PKP), 1009 underwent (deep) anterior lamellar keratoplasty, 746 underwent endothelial keratoplasty, and 309 underwent epithelial transplantation. Over that period the frequency of PKP decreased, whereas the frequency of lamellar keratoplasty increased. The four major surgical indications were bullous keratoplasty (BK 30.0%), regraft (24.2%), post-keratitis scars (17.1%), and keratoconus (11.4%). After dividing the study period into four time periods, we found that BK and regraft increased (from 20.3% to 34.5% and 18.2% to 31.1%, respectively), whereas post-keratitis scars and keratoconus decreased (from 26.0% to 9.5% and 14.1% to 7.2%, respectively) between the first and last period. Pseudophakic or aphakic BK were the major causes of corneal endothelial dysfunction until 2010. Cases of laser-iridotomy-induced BK peaked in 35 eyes (34.3% of BK) in 2000 and declined after 2013. Cases of Fuchs endothelial corneal dystrophy increased from 0 in 1991, to 15 eyes (18.5% of BK) in 2017.

CONCLUSION

Lamellar keratoplasty has replaced PKP in our hospital. BK and regraft have increased, whereas post-keratitis scars and keratoconus have decreased. Laser-iridotomy-induced BK has decreased during the past decade, whereas Fuchs endothelial corneal dystrophy has increased.

Non-intraocular pressure-related revision surgeries after Ahmed glaucoma valve (AGV) implantation in refractory glaucoma

PURPOSE

Ahmed glaucoma valve (AGV) is an effective treatment method for refractory glaucoma (RG), however, additional surgical interventions may be required over the course of follow-up due to complications. Our aim is to investigate the causes, types, and outcomes of revisional surgical interventions apart from revisions aiming IOP control, following AGV implantation in patients with RG.

METHODS

The pre- and postoperative month 1-3-6-12 and last visit examination findings of the patients who underwent various surgical revisions of AGV between January 2015 and April 2018 in our clinic were recorded, as well as the interval between AGV implantation-revision surgery and the presence of any other complications necessitating additional surgery. The success criteria were defined on the basis of need for additional procedures.

RESULTS

Twenty-six eyes of 24 patients were included. The follow-up time and the interval between AGV implantation-surgical revisions were median 12 (6-92) and median 9.7 (1-72) months, respectively. The most common complication requiring revision was tube exposure in 15 (57.7%) followed by tube malposition in 11 (42.3%) eyes. Further interventions were required only in one eye with recurrent exposure.

CONCLUSION

AGV implantation has early and late tube-related complications necessitating revisional surgical interventions; which makes it important to have extended follow-up period for patients with AGV implants. Revisional interventions for AGV implants with tube-related complications are efficient procedures for the majority of patients, but recurrence may occur requiring additional revisions.

Corneal endothelial cell changes and surgical results after Ahmed glaucoma valve implantation: ciliary sulcus versus anterior chamber tube placement

We compared the changes in corneal endothelial cells and surgical outcomes after Ahmed glaucoma valve (AGV) implantation with the valve tip inserted either into ciliary sulcus (CS) or anterior chamber (AC). We retrospectively reviewed the medical records of patients treated with CS AGV (n = 24) and AC AGV (n = 38). We compared the preoperative and postoperative central corneal endothelial cell density (ECD), endothelial cell coefficient of variation (CV), best-corrected visual acuity, intraocular pressure (IOP), number of glaucoma medications, and postoperative complications in the two groups. Both groups had similar baseline characteristics and follow-up period. At the last follow-up, the AC AGV group had significantly higher mean monthly ECD loss (17.47 ± 11.50 cells/mm² vs. 6.40 ± 7.69 cells/mm², p < 0.0001) and greater proportion of mean monthly ECD loss than the CS AGV group (0.84 ± 0.53 vs. 0.36 ± 0.39%, p < 0.0001). Both groups had similar mean monthly CV changes. The qualified success rates at 2 years were 83.3% and 76.3% for the CS AGV and AC AGV groups, respectively. Although similar surgical outcomes including visual acuity, IOP, number of glaucoma medications, and postoperative complications were obtained following CS AGV and AC AGV, corneal ECD loss was higher in the AC AGV group. Thus, CS AGV may be a better surgical option than AC AGV.

Need for Additional Glaucoma Surgery and Complications Following Glaucoma Drainage Device Surgery

PRCIS

In this longitudinal study of patients with open-angle (OAG), pseudoexfoliative (PXE), or neovascular glaucoma (NVG) receiving glaucoma drainage devices (GDD), posttube cumulative rates of reoperation, corneal graft, and visually threatening complications (VT-complications) increased beyond 5 years and were not significantly affected by glaucoma type.

PURPOSE

To study the need for additional glaucoma surgery and development of complications after first GDD surgery in eyes with primary OAG, PXE, or NVG glaucoma.

PATIENTS AND METHODS

There were 306 eyes with OAG (n=185), PXE (n=60), or NVG (n=61) glaucoma who received a first GDD between 1996 and 2017. Outcomes including glaucoma reoperation, corneal graft procedure, and VT-complications after GDD were measured. Kaplan-Meier analysis was used to compare cumulative rate of reaching outcomes over time after GDD placement among the 3 glaucoma groups.

RESULTS

When comparing the OAG, PXE, and NVG groups, there were no significant differences in post-GDD cumulative rates of reoperation (P=0.33), corneal graft (P=0.26), or VT-complications (P=0.65) over time. For all eyes, the overall cumulative rates for each outcome measure increased beyond 5 years, and specific Kaplan-Meier rates (5-y, 10-y) included: reoperation (16%, 25%), corneal graft (6%, 12%), VT-complications (9%, 14%). When comparing specific GDDs, the Ahmed FP7 had a higher cumulative reoperation rate over time compared with the Baerveldt 350 (P=0.019).

CONCLUSION

Glaucoma type did not significantly affect post-GDD cumulative rates of reoperation, corneal graft, and VT-complication among the OAG, PXE, and NVG groups. For all eyes, cumulative rates of reoperation, corneal graft, and VT-complications increased beyond 5 years. The Ahmed FP7 had a significantly higher cumulative reoperation rate compared with the Baerveldt 350 over time.

Rate of Corneal Grafting Post-Glaucoma Drainage Device Use in Pediatric and Adult Patients

PRCIS

Kaplan-Meier analysis was used to compare the rate of corneal grafting after glaucoma drainage device (GDD) placement in pediatric and adult patients. Adults were at an increased risk of receiving a corneal graft after device placement.

PURPOSE

The goal of this study was to compare the rate of corneal graft implantation after GDD placement in pediatric and adult patients.

PATIENTS

Patients receiving a GDD between January 1, 1985 and December 31, 2017 were selected from the medical records. Patients receiving their first device while <18 years of age were considered children for the extent of the study.

METHODS

We compared the rate of receiving a corneal graft after GDD implantation using Kaplan-Meier analysis. Baseline patient characteristics and surgical characteristics were compared using a generalized estimating equation.

RESULTS

Corneal grafting occurred in 8.6% of adults and 4.7% of children from the original cohort. The rate of receiving a corneal graft at 5, 10, and 15 years was 9.4%, 16.8%, 39.4% and 1.6%, 1.6%, 12.5% for adults and children, respectively. However, certain characteristics were different between the 2 groups.

CONCLUSION

Adult patients were more likely to receive a corneal graft after GDD placement. However, pediatric and adult patients differed in the prevalence of preexisting corneal disease, glaucoma type, GDD type used, and types of previous surgeries. Elucidation of the impact of these factors on corneal graft rate requires a larger cohort size.

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 &lt; 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.

Corneal Endothelial Cell Changes After Phacoemulsification Combined with Excisional Goniotomy with the Kahook Dual Blade or iStent: A Prospective Fellow-Eye Comparison

Purpose

To characterize changes in endothelial cell density and morphology following phacoemulsification combined with either excisional goniotomy with the Kahook Dual Blade (KDB-phaco) or first-generation iStent trabecular microbypass implantation (iStent-phaco).

Setting

A single clinical practice.

Methods

Twenty-one adult subjects from one center with visually significant cataract and mild-moderate open-angle glaucoma underwent KDB-phaco or iStent-phaco in one eye and the alternate procedure in the fellow eye as part of a prospective, multicenter, randomized trial. Specular microscopy and pachymetry were performed before and 6–29 months after surgery. Parameters analyzed included change from baseline of endothelial cell density (ECD), the coefficient of variation (CV), the percent of hexagonal cells (%HEX), and central corneal thickness (CCT).

Results

Baseline ECD, CV, %HEX, and CCT were similar between groups. A mean (standard deviation) of 18.2 (5.8) months postoperatively (range 12.5–28.7 months), the change from baseline in ECD was −90 ± 226 cells/mm² (−3.4%) in KDB-phaco eyes (p=0.083) and −239 ± 247 cells/mm² (−9.0%) in iStent-phaco eyes (p<0.001); the change in iStent-phaco eyes was significantly greater than in KDB-phaco eyes (p=0.013). The magnitude of Endothelial Cell Loss (ECL) was not correlated with length of postoperative follow-up time in either group. No significant differences in change from baseline in CV, %HEX, or CCT were noted with the exception of a decrease in %HEX in iStent-phaco eyes (p=0.017). No eyes manifested corneal edema, decompensation, or other cornea-related complications.

Conclusion

Both KDB-phaco and iStent-phaco are associated with postoperative ECL, with iStent-phaco producing significantly greater ECL than KDB-phaco. The clinical significance of these findings is unclear, and future studies are warranted to more robustly characterize long-term effects of glaucoma surgical procedures—with and without permanent implants—on ECD and corneal health and to develop evidence-based guidelines for the pre- and post-operative evaluation of corneal health in eyes undergoing glaucoma surgery.

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.

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.

Corneal Parameters after Tube-Shunt Implantation through the Ciliary Sulcus

PURPOSE

To monitor bilateral corneal parameters after unilateral Baerveldt 350 tube-shunt implantation (Advanced Medical Optics, Santa Ana, CA) through the ciliary sulcus.

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Patients from 1 private glaucoma practice with severe uncontrolled glaucoma treated with sulcus tube-shunt implantation in 1 pseudophakic eye.

METHODS

Specular microscopy data were collected before and after unilateral sulcus tube-shunt implantation from the surgical and the glaucomatous fellow eyes.

MAIN OUTCOME MEASURES

Central corneal endothelial cell density (CECD), coefficient of variation (CV), percent of hexagonal cells, central corneal thickness (CCT), intraocular pressure (IOP), IOP-lowering medications, visual acuity, and complications.

RESULTS

Forty-six patients (mean age, 69.9 years; standard deviation [SD], 4.6 years; range, 20-88 years; male gender, 41.3%) were identified. After surgery, IOP and the number of IOP-lowering medications decreased significantly by 42.3% (P < 0.0001) and 32.1% (P < 0.0001), respectively, in the surgical eye group. Preoperative CECD measured 1807 cells/mm² (SD, 172 cells/mm²) and 1825 cells/mm² (SD, 172 cells/mm²) in the surgical and fellow eyes, respectively (P = 0.92), and compared with baseline, it decreased by 8.6% (P = 0.17) and 3.1% (P = 0.65), respectively, by 24 months. Preoperative CV, percent of hexagonal cells, and CCT were similar in both groups and remained stable. All corneal parameters remained unchanged in a subgroup of 15 patients with low preoperative CECD (1273 cells/mm²; SD, 99 cells/mm²). Best-corrected visual acuity remained stable in both groups. Hyphema occurred in 23.9% of the surgical eyes and resolved with no intervention. We found no sight-threatening complications or corneal failures during follow-up.

CONCLUSIONS

Tube-shunt implantation through the ciliary sulcus in pseudophakic eyes appears relatively safe to the corneal endothelium, demonstrating a small and nonsignificant decline in central CECD compared with baseline and with glaucomatous fellow eyes. No significant disruption to corneal endothelial cell morphologic features, increased corneal thickness, or corneal failures were found during the 24-month follow-up period. A prospective head-to-head comparison to assess the effects of the various methods of tube-shunt implantation on the corneal endothelium is needed.

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.

The Effect of Tube Location on Corneal Endothelial Cells in Patients with Ahmed Glaucoma Valve

PURPOSE

To compare the effects of the Ahmed glaucoma valve (AGV; New World Medical, Rancho Cucamonga, CA) with sulcus versus anterior chamber (AC) tube placement on the corneal endothelial density and morphology over time.

DESIGN

Nonrandomized, interventional study.

PARTICIPANTS

This study included 106 eyes from 101 pseudophakic patients who had the AGV tube placed in the AC (acAGV) and 105 eyes from 94 pseudophakic patients who had the AGV tube placed in the ciliary sulcus (sAGV).

METHODS

All patients underwent preoperative specular microscopy, which was repeated postoperatively in 2019. The patients' demographic information, glaucoma diagnoses, and basic ocular information were obtained on chart review. Anterior segment OCT was conducted for patients who underwent sAGV to evaluate the sulcus tube position. Gonioscopy was performed to document peripheral anterior synechiae (PAS). Linear mixed-effects models were used to compare the different ocular and endothelial measurements between the 2 groups and to identify risk factors for endothelial cell density (ECD) loss over time.

MAIN OUTCOME MEASURES

Monthly change in corneal endothelial measurements, including ECD and coefficient of variation (CV), calculated as the difference between preoperative and postoperative measurements divided by the number of months from the time of surgery to postoperative specular microscopy.

RESULTS

The acAGV and sAGV groups were comparable in all baseline characteristics except that the acAGV group had longer follow-up (37.6 vs. 20.1 months, respectively, P < 0.001). Mean monthly loss in central ECD was significantly more in the acAGV group (mean ± standard deviation: 29.3±29.7 cells/mm²) than in the sAGV group (15.3±20.7 cells/mm², P < 0.0001). Mean monthly change in CV was similar between the 2 groups (P = 0.28). Multivariate analyses revealed that younger age and tube location in the AC were associated with faster central ECD loss (P = 0.02, P < 0.0001, respectively). For patients with sAGV, while PAS was associated with faster central ECD loss (P = 0.002), a more forward tube position tenting the iris was not (P > 0.05).

CONCLUSIONS

Compared with anterior segment placement, ciliary sulcus tube implantation may be a preferred surgery approach to reduce endothelial cell loss in pseudophakic patients.

Glaucoma Drainage Devices and Reasons For Keratoplasty

PRéCIS:: Over 10 years in a tertiary care setting, glaucoma drainage devices (GDDs) have not increased as a reason for keratoplasty.

PURPOSE

The purpose of this study was to determine whether the reasons for keratoplasty have changed between 10 years in a tertiary care setting, with special attention to the rate of GDDs as a reason for keratoplasty.

METHODS

Patients aged 18 years or above who underwent keratoplasty at Mayo Clinic, Rochester, MN from 2005 to 2006 and 2015 to 2016 were studied. All reasons for keratoplasty performed in the study time period are assessed, including patients who previously had a GDD implanted in the same eye. After analyzing the reasons for keratoplasty, we assess whether the reasons for keratoplasty have changed between 2005 to 2006 and 2015 to 2016 in association with the increasing placement of GDDs.

RESULTS

The number of keratoplasty procedures performed in the 2 time periods increased by 62% from 163 (2005 to 2006) to 264 (2015 to 2016), whereas GDD placement increased by 164% from 80 GDD (2005 to 2006) to 211 GDD (2015 to 2016). Although the performance of keratoplasty increased between the 2 points in time, the frequency of each cause for keratoplasty did not change significantly. The majority of keratoplasties were performed due to corneal disease, and GDDs made up a small portion of reasons for keratoplasty (2005 to 2006, 4.29%; 2015 to 2016, 5.68%).

CONCLUSIONS

The frequency of GDDs as a reason for keratoplasty has not changed significantly between 10 years in this tertiary care setting. Patients with GDDs who later required keratoplasty had associated features including multiple surgical procedures and comorbid infection, pseudophakic bullous keratopathy, Fuchs dystrophy, pseudoexfoliation, uveitis, and congenital glaucoma.

Treatment Outcomes Using the PAUL Glaucoma Implant to Control Intraocular Pressure in Eyes with Refractory Glaucoma

PURPOSE

To investigate efficacy 1 year after implantation of a novel glaucoma tube shunt, the PAUL Glaucoma Implant (PGI; Advanced Ophthalmic Innovations, Singapore, Republic of Singapore), in the treatment of eyes with refractory glaucoma.

DESIGN

Clinical trial.

PARTICIPANTS

Glaucoma patients who are recalcitrant to maximum tolerated medical therapy and require tube shunt surgery.

METHODS

Interventional cohort study involving consecutive PGIs implanted at 6 international centers between December 1, 2017, and December 1, 2018. All the participants were followed up for 1 year after surgery.

MAIN OUTCOME MEASURES

The primary outcome measure was failure, defined prospectively as intraocular pressure (IOP) of more than 21 mmHg or less than 20% reduction from the preoperative baseline on 2 consecutive visits, 3 months or more after surgery; persistent late hypotony, defined as IOP of less than 6 mmHg on 2 consecutive visits after 3 months; additional glaucoma surgery; loss of light perception vision; or removal of the implant for any reason.

RESULTS

Of 82 patients enrolled, 74 (74 eyes) completed 12 months of follow-up. The mean age ± standard deviation at enrollment was 62.3±14.7 years, 73.0% were men, and 36.5% had secondary glaucoma. One year after surgery, 4 patients (5.4%) fulfilled the surgical criteria for failure, 68.9% (51/74 eyes) were deemed complete successes, and 93.2% (69/74 eyes) were considered qualified successes. Compared with the medicated preoperative IOP (23.1±8.2 mmHg), the postoperative IOPs at 6 and 12 months were 13.8±4.0 mmHg and 13.2±3.3 mmHg, respectively (P < 0.001). The mean number of IOP-lowering drugs used before surgery and after 12 months of follow-up were 3.3±0.9 and 0.3±0.6, respectively (P < 0.001). Significant postoperative complications included self-limiting shallow anterior chamber (n = 11; 14.9%), hypotony requiring intervention (n = 7; 9.5%), tube shunt occlusion (n = 5; 6.8%), tube exposure (n = 3; 4.1%), and endophthalmitis with resultant loss of vision (n = 1; 1.4%).

CONCLUSIONS

The PGI demonstrated comparable efficacy with other currently available implants, with almost three quarters of the enrolled patients with refractory glaucoma achieving complete surgical success after 1 year of follow-up.

Silicone Tube Miniature Drainage Device Implanted under Scleral Flap for the Surgical Treatment of Glaucoma

PURPOSE

To evaluate the safety and efficacy of a silicone tube miniature drainage device implanted under scleral flap for the surgical treatment of primary open-angle glaucoma (POAG).

METHODS

This is a non-randomized prospective study. Patients with a minimum follow-up of 12 months were analyzed. Demographic information, preoperative and postoperative data including intraocular pressure (IOP), number of medications and complications were recorded.

RESULTS

A total of 33 eyes of 33 patients were included in the analysis. Mean postoperative follow-up was 29.5 ± 6.9 months (range 18-50 months). The mean preoperative IOP was 25.8 ± 7.3 mmHg and decreased to 14.9 ± 4.3, 14.2 ± 3.4 and 14.9 ± 3.3 mmHg at 1 year, 2 years and last follow-up after surgery. The number of medications was decreased from 3.1 ± 1.3 preoperatively to 0.2 ± 0.7, 0.4 ± 0.9 and 0.4 ± 1.0 at 1 year, 2 years and last follow-up, respectively, after surgery. Only six (18.2%) patients used glaucoma medications at last visit. The complete success rates were 87.9% and 78.6%, respectively, at 1 and 2 years postoperatively. The operation-related complications were rare.

CONCLUSIONS

The silicone tube miniature drainage device implanted under the scleral flap was found to be a relatively safe and effective surgery for the treatment of POAG. Longer follow-up periods and larger sample sizes are expected.

Safety and efficacy of high-intensity focused ultrasound in severe or refractory glaucoma

PURPOSE

The aim of this study was to evaluate the efficacy and safety of ultrasonic cyclocoagulation in severe or refractory glaucoma, and to analyze the procedure-related inflammation.

PATIENTS AND METHODS

In this retrospective study, 15 eyes of 13 patients suffering from severe or refractory glaucoma with uncontrolled intraocular pressure of ⩾21 mmHg underwent 8-s ultrasonic cyclocoagulation. A complete ophthalmic evaluation, quality of life assessment using Glau-Qol-17, endothelial cell count, and flare measurement were performed. Primary outcome was qualified surgical success (defined as intraocular pressure reduction from baseline ⩾20% and intraocular pressure >5 mmHg without hypotensive medication adjunction). Secondary outcomes were flare, endothelial cell loss, and quality of life.

RESULTS

Qualified success was achieved in 67% of eyes at 6 months (mean intraocular pressure reduction = 42% in these eyes). During the first month after the procedure, the mean flare reached its maximum value when the intraocular pressure was minimal; the flare slowly decreased until normalization at month 3 when the maximal intraocular pressure was noted. At month 3, there was moderate but significant endothelial cell loss (11%), and no significant alteration in quality of life was demonstrated.

CONCLUSION

The efficacy of ultrasonic cyclocoagulation in the present study is comparable to that reported in the literature. The kinetics of intraocular pressure and flare suggest that postoperative inflammation could be partly responsible for the early intraocular pressure decrease. The moderate endothelial cell loss, which could be caused by localized heating, and the preservation of quality of life confirm the safety of ultrasonic cyclocoagulation.

Changes in corneal endothelial cell density in patients with primary open-angle glaucoma

BACKGROUND

Glaucoma is a group of diseases characterized by a specific pattern of optic nerve neuropathy and retinopathy. Increasing evidence demonstrates glaucoma associated corneal endothelium loss. Direct-compression mechanism due to elevated intraocular pressure (IOP), cell toxicity after long term exposure to preservatives and glaucoma surgery have been reported to be the possible mechanism. Herein, we compare the specular endothelial microscopy in primary open-angle glaucoma (POAG) patients and healthy controls of the same age group to observe the corneal endothelium changes and the correlations to the mean IOP in a Chinese case control study.

AIM

To investigate corneal endothelial cell density in Chinese patients with POAG.

METHODS

A case control study was performed on 60 eyes of 60 patients with POAG. Exclusion criteria included history of corneal diseases, intraocular diseases, contact lens use, ocular trauma or surgery (including intraocular surgery and laser treatment), congenital abnormalities or systemic diseases such as diabetes. Intraocular pressure was measured using Goldmann tonometry. Indirect specular microscopy (TOPCON SP-2000P) was performed on central corneas and endothelial images were acquired. Endothelial cell density, area and cell counts were analyzed.

RESULTS

Endothelial cell density was 2959 ± 236 cells/mm² in healthy controls and 2757 ± 262 cells/mm² in patients with POAG. The POAG eyes had significantly lower endothelial cell density compared to healthy control eyes (P < 0.001). In the POAG group, endothelial cell density was 2686 ± 233 cells/mm² in the patients receiving medication and 2856 ± 272 cells/mm² in the untreated subgroup. The eyes receiving medication had significantly lower endothelial cell density compared to untreated eyes. There was a negative correlation between cell density and mean IOP (r = −0.286, P = 0.004), positive correlation between the average cell area and mean IOP (r = 0.228, P = 0.022), maximum cell area and mean IOP (r = 0.218, P = 0.029) and minimum cell area and mean IOP (r = 0.290, P = 0.003). The percentage of hexagonal cells was not correlated with mean IOP.

CONCLUSION

Patients with POAG have lower corneal endothelial cell density than healthy controls of the same age. This may be attributed to mechanical damage from elevated IOP and toxicity of glaucoma medications.

New developments in tube shunt surgery

PURPOSE OF REVIEW

This article reviews recent studies related to tube shunt surgery.

RECENT FINDINGS

Medical claims data and surveys of glaucoma surgeons demonstrate that tube shunts are being selected with increasing frequency as an alternative to trabeculectomy. A 5-year pooled analysis of the Ahmed Baerveldt comparison study and Ahmed versus Baerveldt study found a higher rate of surgical success with the Baerveldt glaucoma implant compared with the Ahmed glaucoma valve, but Baerveldt implantation carried a higher risk of hypotony. The primary tube versus trabeculectomy study showed trabeculectomy with mitomycin C produced greater intraocular pressure reduction with fewer glaucoma medications compared with tube shunt surgery as a primary procedure at 1 year, but trabeculectomy had a higher rate of postoperative complications. Adjunctive use of antifibrotic agents may enhance the success of tube shunt surgery. Implantation of a second tube shunt is effective in lowering intraocular pressure following primary tube shunt failure, but good results have also been reported with cyclophotocoagulation. Endothelial cell loss, diplopia, and tube shunt erosion are complications associated with these devices.

SUMMARY

The popularity of tube shunts has grown in recent years. Clinical trials and retrospective studies have provided valuable information to guide surgeons in the use of tube shunts. Increased efficacy of glaucoma procedures generally occurs at the cost of a higher risk of surgical complications.

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.

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.

Rapid Intraocular Tube Trimming for Glaucoma Drainage Implant Devices

PURPOSE

To describe a new approach for shortening silicone tubes of glaucoma drainage devices (GDDs).

MATERIALS AND METHODS

A retrospective intervention case series describing 3 patients undergoing the same treatment at a single institutional center RESULTS:: Three patients underwent successful ab interno trimming of GDD silicone tubes without complication CONCLUSIONS:: This technique allows for rapid and successful shortening of GDD tubes via an ab interno approach avoiding risks of traditional glaucoma tube trimming approaches.

Ahmed glaucoma valve implant: surgical technique and complications

Implantation of Ahmed glaucoma valve is an effective surgical technique to reduce intraocular pressure in patients affected with glaucoma. While in the past, the use of this device was reserved to glaucoma refractory to multiple filtration surgical procedures, up-to-date mounting experience has encouraged its use also as a primary surgery for selected cases. Implantation of Ahmed glaucoma valve can be challenging for the surgeon, especially in patients who already underwent previous multiple surgeries. Several tips have to be acquired by the surgeon, and a long learning curve is always needed. Although the valve mechanism embedded in the Ahmed glaucoma valve decreases the risk of postoperative hypotony-related complications, it does not avoid the need of a careful follow-up. Complications related to this type of surgery include early and late postoperative hypotony, excessive capsule fibrosis around the plate, erosion of the tube or plate edge, and very rarely infection. The aim of this review is to describe surgical technique for Ahmed glaucoma valve implantation and to report related complications.

Changes in Corneal Endothelial Cell after Ahmed Glaucoma Valve Implantation and Trabeculectomy: 1-Year Follow-up

Purpose

To compare changes in corneal endothelial cell density (CECD) after Ahmed glaucoma valve (AGV) implantation and trabeculectomy.

Methods

Changes in corneal endothelium in patients that underwent AGV implantation or trabeculectomy were prospectively evaluated. Corneal specular microscopy was performed at the central cornea using a non-contact specular microscope before surgery and 6 months and 12 months after surgery. The CECD, hexagonality of the endothelial cells, and the coefficient of variation of the cell areas were compared between the two groups.

Results

Forty eyes of 40 patients with AGV implantation and 28 eyes of 28 patients with trabeculectomy were studied. Intraocular pressure in the AGV implantation group was significantly higher than that in the trabeculectomy group (p < 0.001), but there was no significant difference in other clinical variables between the two groups. In the AGV implantation group, the mean CECD significantly decreased by 9.4% at 6 months and 12.3% at 12 months compared with baseline values (both, p < 0.001), while it decreased by 1.9% at 6 months and 3.2% at 12 months in the trabeculectomy group (p = 0.027 and p = 0.015, respectively). The changes at 6 months and 12 months in the AGV implantation group were significantly higher than those in the trabeculectomy group (p = 0.030 and p = 0.027, respectively). In the AGV implantation group, there was a significant decrease in the CECD between baseline and 6 months and between 6 months and 12 months (p < 0.001 and p = 0.005, respectively). However, in the trabeculectomy group, a significant decrease was observed only between baseline and 6 months (p = 0.027).

Conclusions

Both the AGV implantation group and the trabeculectomy group showed statistically significant decreases in the CECD 1 year after surgery. The decrease in CECD in the AVG implantation group was greater and persisted longer than that in the trabeculectomy group.