Effect of Mitomycin-C Augmented Trabeculectomy on Corneal Endothelial Cells

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.

Endothelial cell loss associated with minimally invasive glaucoma surgery

PURPOSE OF REVIEW

Minimally invasive glaucoma surgery (MIGS) represents a safer, albeit moderately effective surgical option for intraocular pressure control. However, the CyPass Micro-Stent (Alcon Laboratories) was withdrawn from the market in 2018 as the COMPASS-XT study demonstrated greater cornea endothelial cell (CEC) loss in patients who received the CyPass Micro-Stent with phacoemulsification compared with phacoemulsification alone. This led to the increased attention on MIGS-associated CEC loss and thus, this review will summarise the recent, available evidence on MIGS-associated CEC loss.

RECENT FINDINGS

Prospective clinical trials and retrospective observational studies published between 2011 and 2021 reported a wide range of 12 month CEC loss from 'insignificant', and up to 14.6%, for phacoemulsification combined with various MIGS procedures. Recent clinical trials over the same time period reported CEC loss of 12.8-15.2% associated with phacoemulsification alone.

SUMMARY

Apart from the CyPass Micro-Stent clinical trial, no other studies on combined phacoemulsification with MIGS that is 'phaco-plus' procedures have reported a higher short-term CEC loss compared with phacoemulsification alone. However, studies that specifically examine postprocedural CEC loss following phacoemulsification compared to 'phaco-plus' procedures over a longer follow-up period are required.

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.

The corneal endothelium: clinical review of endothelial cell health and function

The endothelial cell is a critical structure within the cornea and is responsible for maintaining corneal clarity through its pump function. Endothelial cells are lost over time naturally but can be injured medically, surgically, or as a part of various dystrophies. Monitoring of endothelial cells can be performed clinically or more formally with specular microscopy. In cases of significant compromise, endothelial cells can be transplanted by various endothelial keratoplasty techniques. The future pipeline is bright for possible endothelial cell regeneration and rehabilitation. This article reviews these topics in depth to provide a comprehensive look at the structure and function of the endothelial cell, etiologies of endothelial cell damage, detailed review of iatrogenic causes of endothelial cell loss, and management strategies.

One-Year Randomized Comparison of Safety and Efficacy of Trabeculectomy with Mitomycin C Sub-Tenon Injection versus Mitomycin C-Infused Sponges

PURPOSE

To compare the safety and efficacy of sub-Tenon injection of mitomycin C (MMC) with application of MMC-infused sponges during trabeculectomy.

DESIGN

Single-center randomized clinical trial.

PARTICIPANTS

A total of 56 eyes of 49 patients with open-angle glaucoma were included in this clinical trial.

METHODS

In this single-center randomized clinical trial, 56 eyes of 49 patients underwent trabeculectomy with MMC for primary open-angle glaucoma. Patients were randomized into 2 groups. The injection group received a sub-Tenon injection of 0.15 ml of 0.01% MMC diluted with preservative free lidocaine 2% (n = 27). In the sponges group, sponges soaked in 0.02% MMC were applied under the Tenon's capsule and the scleral flap for 2 minutes (n = 29). Intraocular pressure, endothelial cell count, best-corrected visual acuity, and number of intraocular pressure (IOP)-lowering medications were assessed before surgery and 1 week; 1, 3, and 6 months; and 1 year after surgery. Complete success was defined as IOP of 14 mmHg or less without medication. Bleb morphologic features were assessed using the Indiana Bleb Appearance Grading Scale bleb grading system.

MAIN OUTCOME MEASURES

Intraocular pressure reduction was the primary outcome. Bleb morphologic features and endothelial cell counts (ECCs) were secondary outcomes.

RESULTS

Mean IOP in the sponges group decreased from 30.5 ± 7.4 mmHg at baseline to 12.6 ± 5.9 mmHg at 1 year (P < 0.001); in the injection group, IOP decreased from 29.3 ± 6.8 mmHg at baseline to 12.7 ± 4.3 mmHg at 1 year (P < 0.001). No difference in IOP between the 2 groups was noted at any visit (P < 0.001). Surgical success was 81.5% and 82.8% in the injection and sponges groups, respectively, at 1 year. Mean ECC values were unchanged from baseline to 1 year after surgery for both groups (P = 0.444). Complication rates were similar in the 2 groups. Bleb morphologic features showed differences in the appearance and grading of the blebs between the 2 groups at 1 year, showing larger extent, lower height, and less vascularization in the injection group.

CONCLUSIONS

Sub-Tenon injection of MMC during trabeculectomy seems to be as safe and as efficacious as conventional application of MMC with sponges at 1 year after surgery. Bleb morphologic features show notable differences that may suggest a better long-term outcome.

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.

Iatrogenic corneal diseases or conditions

Any prescribed or self-administered therapy carries inherent risks of secondary adverse events. While the volume of treatments being administered through healthcare systems has been increasing, scientific advancements in our understanding of the mechanisms of pharmaceutical side effects and complications from procedures now allow us to reduce the risk of non-intentional damage to ocular health. This review summarizes the most common and leading causes of iatrogenic visual impairment, corneal diseases, and conditions that present in a general ophthalmologic practice, including a comprehensive analysis of their pathophysiology and recommendations for management and prophylaxis.Iatrogenic corneal diseases and conditions can arise from topical drugs, contact lens use, eye surgeries and procedures, systemic drugs, non-ophthalmological events, and cosmetic procedures. Topical and systemic drugs may disturb tear film homeostasis or result in ocular surface deposits. The use of ill-fitted contact lenses can trigger eye discomfort and poor hygiene conditions that can predispose to severe infections. Procedures to the eye may result in a variety of anatomical and functional complications that ophthalmologists should be aware of how to avoid or at least be prepared to manage if they occur. Even non-ophthalmological events such as non-invasive ventilation, radiation therapies and, immune-based conditions, or cosmetic procedures such as eyelash growth and fillers, can result in unwanted damage to the ocular surface.

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.

Learning from the past: Mitomycin C use in trabeculectomy and its application in bleb-forming minimally invasive glaucoma surgery

Trabeculectomy has been performed since the mid-1960s and remains the gold standard for glaucoma surgery. Newer surgical options have evolved, collectively referred to as minimally invasive glaucoma surgeries. Despite producing large intraocular pressure decreases, full-thickness procedures into the subconjunctival space may be limited by fibrosis. Mitomycin C (MMC) and 5-fluorouracil have been in use with trabeculectomy with good evidence of significantly increased success at the cost, however, of an increased risk of complications. Off-label MMC application can be found in almost all clinical trials, including in combination with minimally invasive glaucoma surgeries. We explore current evidence for MMC use in trabeculectomy and how this may differ for minimally invasive glaucoma surgery devices and analyze the range of agents and doses that are used. Although we found that most studies could not show any correlation between MMC dosage and the surgical outcome, the success rates with the Xen® microshunt seemed to be higher when using 20 mcg of MMC than when using 10 mcg. Certain important methodological considerations make this hard to confirm definitively, and other factors such as placement of the device may play a more substantial role. For the PreserFlo® microshunt, preliminary data suggest higher success rates with higher MMC dosage at the cost of higher device-related adverse events and reoperations. Although the ideal dose still needs to be established, it seems very likely that MMC provides significant improvement in outcomes in bleb-forming minimally invasive glaucoma procedures.

Factors influencing the reduction in corneal endothelial cells after Ex-Press® surgery

PURPOSE

We investigated the factors that influence the reduction in corneal endothelial cells after Ex-Press^® surgery.

METHODS

This was a retrospective study. We included patients who had undergone Ex-Press surgery and were followed up for > 2. We analyzed the corneal endothelial cell density (ECD) before and after Ex-Press surgery. We investigated the insertion position (Ex-Press device was inserted into cornea or trabecular meshwork (TM)), Ex-Press-iris touch, cornea-iris touch, peripheral anterior synechiae, history of trabeculotomy, history of selective laser trabeculoplasty, type of glaucoma, and simultaneous cataract surgery as influencing factors. We used multivariate analysis to determine the factors influencing the reduction rate of ECD.

RESULTS

We included 129 eyes. The mean of ECD had decreased 7.0% at 2 years. Ex-Press surgeries significantly decreased the ECD after 2 years (p = 0.0118). As a result of the multivariate analysis, the factor that led to a significantly faster reduction in ECD was the insertion position of the Ex-Press (p < 0.0001). The reduction rate of ECD after 2 years in cases of insertion into the cornea (27 eyes) was 15.1 ± 3.6%, and in cases of insertion into a TM (102 eyes), it was 5.2 ± 1.4%.

CONCLUSIONS

Insertion into the cornea was a risk factor for rapid ECD loss. The Ex-Press should be inserted into a TM for long-term protection of the corneal endothelial cells.

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.

Comparison between Ologen implant and different concentrations of Mitomycin C as an adjuvant to trabeculectomy surgery

CONTEXT:

Trabeculectomy is the most common surgical procedure for treatment of glaucoma. To improve success rates, adjuvants were utilized as Mitomycin C (MMC) and Ologen implant.

AIMS:

This study aims to establish efficacy and safety of Ologen implant versus MMC in trabeculectomy.

SETTING AND DESIGN:

A prospective, comparative clinical study was conducted at the Department of Ophthalmology, Assiut University, between December 2014 and April 2016.

SUBJECTS AND METHODS:

Patients with primary open-angle glaucoma (OAG), primary narrow-angle glaucoma and secondary OAG were assigned equally to trabeculectomy with Ologen, 0.4 mg/mL or 0.2 mg/mL MMC. The study outcome measures were reduction in intra-ocular pressure (IOP), success rates, survival analysis, and rate of complications.

STATISTICAL ANALYSIS USED:

SPSS software Version 17.0 (SPSS, Inc., IL, USA) was utilized.

RESULTS:

Thirty eyes were included in the study. Mean baseline IOP in Ologen, MMC 0.4 and MMC 0.2 groups were 27.43 ± 2.97, 28.4 ± 3.24, and 27.56 ± 2.69 mmHg, respectively. At week 24 follow-up, mean IOP in Ologen, MMC 0.4 and MMC 0.2 groups were 18.55 ± 3.18, 16.2 ± 3.22, and 16.93 ± 3.04 mmHg, respectively. No significant inter-group difference was noticed at any visits. Complete success was achieved in 10%, 40%, and 30%, whereas incomplete success in 70%, 50%, and 60%, respectively in Ologen, MMC 0.4 and MMC 0.2 groups. No treatment group difference was reported by Kaplan–Meier analysis. Shallow anterior chamber occurred more in Ologen and MMC 0.4 groups. A single case of serous choroidal effusion had occurred in MMC 0.4 group.

CONCLUSION:

Ologen implant is a promising alternative to MMC for improving the success rate of trabeculectomy.

TFOS DEWS II iatrogenic report

Dry eye can be caused by a variety of iatrogenic interventions. The increasing number of patients looking for eye care or cosmetic procedures involving the eyes, together with a better understanding of the pathophysiological mechanisms of dry eye disease (DED), have led to the need for a specific report about iatrogenic dry eye within the TFOS DEWS II. Topical medications can cause DED due to their allergic, toxic and immuno-inflammatory effects on the ocular surface. Preservatives, such as benzalkonium chloride, may further aggravate DED. A variety of systemic drugs can also induce DED secondary to multiple mechanisms. Moreover, the use of contact lens induces or is associated with DED. However, one of the most emblematic situations is DED caused by surgical procedures such as corneal refractive surgery as in laser-assisted in situ keratomileusis (LASIK) and keratoplasty due to mechanisms intrinsic to the procedure (i.e. corneal nerve cutting) or even by the use of postoperative topical drugs. Cataract surgery, lid surgeries, botulinum toxin application and cosmetic procedures are also considered risk factors to iatrogenic DED, which can cause patient dissatisfaction, visual disturbance and poor surgical outcomes. This report also presents future directions to address iatrogenic DED, including the need for more in-depth epidemiological studies about the risk factors, development of less toxic medications and preservatives, as well as new techniques for less invasive eye surgeries. Novel research into detection of early dry eye prior to surgeries, efforts to establish appropriate therapeutics and a greater attempt to regulate and oversee medications, preservatives and procedures should be considered.

Safety of Using Matrix Metalloproteinase Inhibitor in Experimental Glaucoma Filtration Surgery

We evaluated the safety of matrix metalloproteinase (MMP) inhibitor in experimental glaucoma filtration surgery in an animal model. Fifteen New Zealand white rabbits underwent an experimental trabeculectomy and were randomly allocated into 3 groups according to the adjuvant agent: no treatment group (n = 5), 0.02% mitomycin C (MMC) soaking group (n = 5), and MMP inhibitor (ilomastat) subconjunctival injection group (n = 5). Slit lamp examination with Seidel testing, pachymetry, and specular microscopy was performed preoperatively and postoperatively. The conjunctiva and ciliary body toxicity were evaluated with scores according to the pathologic grading systems. Electron microscopy was used to examine the structural changes in cornea, conjunctiva, and ciliary body. In the ilomastat-treated group, there was no statistically significant change in central corneal thickness preoperatively and at 28 days postoperatively (P = 0.655). There were also no significant changes in specular microscopy findings over the duration of the study in the ilomastat-treated group. The conjunctival toxicity score was 1 in the control group, 1.5 in the ilomastat-treated group, and 2 in the MMC-treated group. When assessing ciliary body toxicity scores, the ilomastat-treated group score was 0.5 and the MMC-treated group score was 1.5. Transmission electron microscopy did not show structural changes in the cornea and ciliary body whereas the structural changes were noticed in MMC group. A single subconjunctival injection of MMP inhibitor during the experimental trabeculectomy showed a less toxic affect in the rabbit cornea, conjunctiva, and ciliary body compared to MMC.

Corneal Endothelial Cell Density in Children: Normative Data From Birth to 5 Years Old

PURPOSE

To establish a normative database of endothelial cell density (ECD) using in vivo specular microscopy in children under 5 years old.

DESIGN

Cross-sectional study.

METHODS

Specular microscopy was performed during a clinic visit in cooperative children in the standard upright position. In uncooperative children, specular microscopy was performed in the lateral decubitus position under general anesthesia, before surgery for other reasons. Corneal diameter (CD) was measured in children undergoing general anesthesia and was stratified according to age.

RESULTS

One hundred and eighteen eyes of 118 patients were included in the study. The mean patient age was 2.6 ± 1.4 years (range 0.1-5 years) and the mean ECD was 3746 ± 370 cells/mm² (range 3145-5013 cells/mm²). The mean CD under 2 years of age was 11.85 ± 0.57 mm (n = 40, range 10.50-12.75 mm). Up to 2 years of age, ECD was more inversely correlated with CD than with age (r = -0.61, P < .0001; r = -0.38, P = .01, respectively). In contrast, after the age of 2 years, the ECD was inversely correlated with age but not with CD (r = -0.27, P = .02; r = -0.24, P = .2). Between the first and second year of life, the rate of ECD decrease was significantly higher than between 2 and 5 years of age (8.2%, 334 cells/mm² vs 2.7%, 100 cells/mm² a year, respectively).

CONCLUSION

In the first 2 years of life there is a rapid decline in ECD, which is likely related to growth in CD and hence surface area. After the cornea reaches adult size, the ECD decreases at a rate similar to that reported in adults.