A novel approach to suprachoroidal drainage for the surgical treatment of intractable glaucoma

Clinical and Optical Coherence Tomography Evidence of Aqueous Humor Flow from the Suprachoroidal Space to Conjunctival Lymphatics

A surgical technique was developed to enhance aqueous humor (AH) flow through the non-trabecular outflow pathway by rerouting it from the anterior chamber (AC) to the suprachoroidal space (SCS) without detaching the ciliary body from the scleral spur. Medium- and long-term surgical outcomes were retrospectively analyzed in a case series of 58 glaucoma patients. At 6, 12, and 24 months, the mean IOP decreased from 27.8 ± 8.3 to 14.9 ± 5.0 mmHg, median 15.0 (25th percentile (p25)13.0; 75th percentile (p75) 18.0) and 15.2 ± 3.3 mmHg, and hypotensive medication use reduced from a median (p25; p75) of 3 (2; 3) to 0 (0; 2), 0 (0; 2), and 0 (0; 1.5), respectively. Intra- and postoperative complications were few and manageable. Following surgery, no bleb formation occurred in any of the cases (as confirmed by optical coherence tomography). Conjunctival lymphatic vessels (CLVs) developed in 50% of eyes (29/58). Clinically, they developed directly from sclera and had no connection to the surgical site. Analysis further showed that the development of CLVs and their longer visibility period had poor prognostic value for IOP control. If the fluid flow from the SCS to CLVs was resistance-free, no CLV development was evident. However, if any resistance existed in the flow, the fluid accumulated in lymphatics, resulting in their engorgement. The proposed technique was safe and effective in decreasing IOP in glaucoma patients by enhancing AH flow from the SCS to CLVs via connecting intrascleral microchannels.

[Minimally invasive glaucoma surgery-Comparison of angle based procedures]

Surgical procedures are playing an increasing role in the care of patients with glaucoma. Within the last decade, new surgical procedures have been established, which are summarized under the term minimally invasive glaucoma surgery (MIGS). A wide variety of different procedures are aimed at the structures in the angle of the anterior chamber, such as the trabecular meshwork and Schlemm's canal, to improve the physiological outflow or to improve the alternative uveoscleral outflow. The implementation of the treatment goal differs in the individual procedures, as does the maximum pressure reduction that can be achieved. Compared to trabeculectomy with the use of cytostatic agents, the achievable pressure reduction is usually significantly lower. In contrast, the significantly lower intraoperative and postoperative complication rates are emphasized as an advantage of these procedures. With increasing clinical experience and the growth of sufficient data on these new surgical procedures, a well-founded classification in the treatment algorithm of glaucoma surgery becomes easier; nevertheless, due to the small differences with respect to efficacy and safety profile, the final decision for an individual procedure often remains dependent on the surgeon's personal preferences.

Modified Deep Sclerectomy for the Surgical Treatment of Glaucoma

Purpose:

To report the short-term outcomes of modified deep sclerectomy (MDS) in the management of open angle glaucoma.

Methods:

This prospective, non-randomized, controlled study included 105 eyes (105 patients) with open angle glaucoma. Eyes were categorized as follows: trabeculectomy (30 eyes), MDS (27 eyes), phacotrabeculectomy (28 eyes), and phaco-MDS (20 eyes). The MDS technique involved removal of a third scleral flap to expose the suprachoroidal space and excision of a trabecular block. A two-site approach was used for combined surgeries. Main outcome measures included intraocular pressure (IOP), number of glaucoma medications, and complications. Treatment success was defined as an IOP of 6–15 mmHg and/or a 30% reduction in IOP.

Results:

All groups showed significant decrease in IOP and number of medications (both P s < 0.001). The MDS group had a higher IOP (13.9 ± 3.8 vs. 12.4 ± 2.5 mmHg, P = 0.080) and required more medications (P = 0.001) than the trabeculectomy group at 1 year. The MDS group had a higher baseline IOP than the trabeculectomy group (P = 0.004) and both the groups showed similar IOP reductions (33.3% vs. 25.7%, P = 0.391). The phaco-MDS and phacotrabeculectomy groups had comparable IOP (13.3 ± 3.1 vs. 12.4 ± 3.1 mmHg, P = 0.354), number of medications (P = 0.594), and IOP reduction (P = 0.509) at 1-year follow-up visit. The trabeculectomy and phacotrabeculectomy groups developed more wound leaks (P = 0.043) and required more bleb needling during the early postoperative period (P < 0.001).

Conclusion:

The MDS technique seems to be slightly inferior to trabeculectomy, but when combined with phacoemulsification, is safer and results in similar IOP outcomes.

Intra-Scleral Ciliary Sulcus Suprachoroidal Microtube: Making Supraciliary Glaucoma Surgery Affordable

PURPOSE

The suprachoroidal space (SCS) has been a successful target to lower intraocular pressure (IOP) in glaucoma patients. We present the results of 4 patients who underwent a novel glaucoma surgical procedure to lower IOP: Intrascleral Ciliary Sulcus-Suprachoroidal Microtube.

METHODS

A sterile medical grade silicone microtube (Tube extender, New World Medical) was surgically placed to drain aqueous from the posterior chamber ciliary sulcus of the eye to the SCS. The internal diameter of the tube was 300 um and the length varied from 8-10mm. After informed consent was obtained and witnessed, this procedure was performed in glaucoma patients with pseudophakia. The tube was placed intrasclerally beneath an inferotemporal sclera flap (50% thickness approximately 4mm x 4mm). The anterior end of the tube was inserted into the ciliary sulcus approximately 2mm from the limbus and the posterior end was placed into the SCS approximately 4mm from the limbus. The microtube was sutured to the sclera with a 10-0 nylon suture. 8-0 vicryl sutures were used to close the sclera flap and the conjunctiva inferotemporally.

RESULTS

All 4 patients had lower IOP. The average reduction of IOP was 36% at 3 months. The amount of glaucoma medications per patient at 3 months dropped from an average of 3 to 0.25. The risks are similar to traditional glaucoma incisional surgery.

CONCLUSION

This new technique of Intrascleral Ciliary Sulcus-Suprachoroidal Microtube in all four patients with mild, moderate, and advanced glaucoma demonstrated a significant lowering of IOP and a decrease in the number of medications. Further research is required to assess long term efficacy and safety.

Trabeculectomy with Suprachoroidal Derivation in Eyes with Uncontrolled Glaucoma: A Case Series with a 24-Month Follow-up

Introduction

The aim of this study was to evaluate the efficacy of trabeculectomy with suprachoroidal derivation in eyes with uncontrolled glaucoma after a 24-month follow-up period.

Methods

This was a prospective uncontrolled non-randomized case series. All patients scheduled for a trabeculectomy due to uncontrolled glaucoma at the “Instituto de Glaucoma y Catarata” (Lima, Peru) between 2011 and 2014 were included. Thee patients underwent trabeculectomy with mitomycin C and suprachoroidal derivation with two autologous scleral flaps. Postsurgical follow-up visits took place on day 1, and at 1, 6, 12, 18 and 24 months. Best corrected visual acuity (BCVA), intraocular pressure (IOP) and complications at each control were registered. Main outcome measures were IOP reduction, number of glaucoma medications and complication rate. Postoperative IOP of > 21 mmHg, < 5 mmHg, additional glaucoma surgery or severe complications were considered as indications of failure.

Results

Thirty-three participants (41 eyes) were included in the study, of whom 27 (81.82%) (31 eyes [75.61%]) finished the 24 months of follow-up. At the end of the follow-up, mean IOP had decreased by 11.29 ± 9.32 mmHg (p < 0.001), and glaucoma medication usage in 25 (25/31; 80.65%) eyes had stopped. Ten (10/41; 24.39%) patients complained of blurred vision, and 15 (15/41; 36.59%) patients referred to foreign body sensation the first day after surgery; both sensations resolved spontaneously after 1 week in all cases. No failures, significant changes in BCVA (p = 0.387) or severe complications were found.

Conclusions

In this case series, trabeculectomy with suprachoroidal derivation exhibited high efficacy and safety after a 24-month follow-up. A larger sample with a control group is needed to confirm our initial findings.

Ahmed glaucoma valve implantation versus suprachoroidal silicone tube implantation following the injection of bevacizumab into the anterior chamber in patients with neovascular glaucoma

PURPOSE

This study compared the efficacy and safety of Ahmed glaucoma valve (AGV) implantation versus suprachoroidal silicone tube (SST) implantation after the injection of bevacizumab into the anterior chamber in patients with neovascular glaucoma.

METHODS

Patients were randomly assigned to undergo AGV or SST implantation. Bevacizumab was injected into the anterior chamber at a dosage of 1.25 mg/0.1 mL, 1 week before surgery. Intraocular pressure (IOP) control, complication, and success rates were compared between the groups. Success was defined as a final IOP > 5 mmHg, < 22 mmHg with or without any antiglaucoma drug.

RESULTS

A total of 23 patients were enrolled in the study, including 13 (56.5%) in the AGV group (group 1) and 10 (43.5%) in the SST group (group 2). The mean baseline IOP was 42.0 ± 9.1 mmHg in group 1 and 39.5 ± 10 mmHg in group 2 (p > 0.05). The mean IOP was 16.9 ± 7.0 mmHg in group 1 and 12.5 ± 6.7 mmHg in group 2 on the first day after surgery. After a mean follow-up period of 19.4 ± 5.2 months, success was achieved in 12 (92.3%) patients in group 1 and in 1 (10%) patient in group 2. There was a statistically significant difference in terms of the success rate between groups (p < 0.05). Complications included hyphema in three (23%) patients, obstruction of the AGV tube by iris tissue in one (7.7%) patient, and tube exposure in one patient (7.7%) in group 1. Suprachoroidal silicone tube dislocation to the anterior chamber was observed in one (10%) patient in group 2.

CONCLUSION

AGV implantation after the injection of bevacizumab into the anterior chamber had a higher success rate than SST implantation. Complications were seen more frequently in the AGV group.

Study of the safety of long-term drainage of the suprachoroidal space with a polyurethane drainage tube (experimental study)

The article describes the results of an experimental study of the safety of long-term drainage of the suprachoroidal space (SCS) with a polyurethane drainage tube. The work was performed on 10 rabbits (20 eyes) of the Chinchilla breed, in which a polyurethane drainage tube was implanted in the SCS. The safety of the proposed method was assessed using histopathological examination, eye biomicroscopy, ophthalmoscopy, fluorescein angiography. The study results show the safety of the polyurethane tube presence in the suprachoroidal space for up to 30 days. At the same time, the presence of the polyurethane drainage tube in the SCS for more than 30 days leads to irreversible pathological changes of inner eye tunics.

Choroidal Changes After Suprachoroidal Injection of Triamcinolone Acetonide in Eyes With Macular Edema Secondary to Retinal Vein Occlusion

PURPOSE

To evaluate choroidal and suprachoroidal changes following suprachoroidal injection of triamcinolone acetonide injectable suspension (CLS-TA), in eyes with macular edema due to retinal vein occlusion (RVO).

DESIGN

Prospective cohort study within a randomized, controlled phase 2 clinical trial.

METHODS

Enhanced depth imaging optical coherence tomography (EDI-OCT) images were analyzed from 38 eyes of 38 treatment-naïve patients with macular edema due to RVO, enrolled in the prospective Suprachoroidal Injection of Triamcinolone Acetonide with Intravitreal Aflibercept in Subjects with Macular Edema Due to Retinal Vein Occlusion (TANZANITE) study who received either a suprachoroidal injection of CLS-TA with an intravitreal injection of aflibercept (combination arm) or only an intravitreal injection of aflibercept (monotherapy arm), followed by monthly intravitreal aflibercept injections in both arms based on pro re nata criteria.

RESULTS

Macular choroidal thickness measured to the outer choroidal vessel lumen (vascular choroidal thickness, VCT), outer choroid stroma (stromal choroidal thickness, SCT), or inner scleral border (total choroidal thickness, TCT) showed no significant changes over 3 months in both study arms (P = .231-.342). Eyes that received combination therapy showed a trend toward thickening of the suprachoroidal space (SCS) compared with monotherapy alone (13.4 μm vs 5.3 μm at 3 months; P = .077). In the 15 eyes that demonstrated a visible SCS at baseline, the SCS expanded significantly after suprachoroidal CLS-TA injection (16.2 μm to 27.8 μm at 3 months; P = .033).

CONCLUSIONS

Suprachoroidal injection of CLS-TA does not alter choroidal thickness in eyes with macular edema due to RVO, but may result in expansion of the SCS.

Device-modified trabeculectomy for glaucoma

BACKGROUND

Glaucoma is an optic neuropathy that leads to vision loss and blindness. It is the second most common cause of irreversible blindness worldwide. The main treatment for glaucoma aims to reduce intraocular pressure (IOP) in order to slow or prevent further vision loss. IOP can be lowered with medications, and laser or incisional surgeries. Trabeculectomy is the most common incisional surgical procedure to treat glaucoma. Device-modified trabeculectomy is intended to improve drainage of the aqueous humor to lower IOP. Trabeculectomy-modifying devices include Ex-PRESS, Ologen, amniotic membrane, expanded polytetrafluoroethylene (E-PTFE) membrane, Gelfilm and others. However, the effectiveness and safety of these devices are uncertain.

OBJECTIVES

To assess the relative effectiveness, primarily with respect to IOP control and safety, of the use of different devices as adjuncts to trabeculectomy compared with standard trabeculectomy in eyes with glaucoma.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2014, Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to December 2014), EMBASE (January 1980 to December 2014), PubMed (1948 to December 2014), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to December 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 22 December 2014.

SELECTION CRITERIA

We included randomized controlled trials comparing devices used during trabeculectomy with trabeculectomy alone. We also included studies where antimetabolites were used in either or both treatment groups.

DATA COLLECTION AND ANALYSIS

We used standard procedures expected by Cochrane.

MAIN RESULTS

We found 33 studies that met our inclusion criteria, of which 30 were published as full-length journal articles and three as conference abstracts. Only five studies have been registered. The 33 studies included a total of 1542 participants with glaucoma, and compared five types of devices implanted during trabeculectomy versus trabeculectomy alone. Five studies reported the use of Ex-PRESS (386 participants), eight studies reported the use of Ologen (327 participants), 18 studies reported the use of amniotic membrane (726 participants), one study reported the use of E-PTFE (60 participants), and one study reported the use of Gelfilm (43 participants). These studies were conducted in North America, South America, Europe, Asia, and the Middle East. Planned participant follow-up periods ranged from three months to five years. The studies were reported poorly which limited our ability to judge risk of bias for many domains. Only two studies explicitly masked outcome assessment so, we rated 31 studies at high risk of detection bias.Low-quality evidence from three studies showed that use of Ex-PRESS compared with trabeculectomy alone may be associated with a slightly lower IOP at one year (mean difference (MD) -1.58 mm Hg, 95% confidence interval (CI) -2.74 to -0.42; 165 eyes). Cataract surgery and hyphema may be less frequent in the Ex-PRESS group than in the trabeculectomy-alone group (cataract surgery: risk ratio (RR) 0.32, 95% CI 0.14 to 0.74, 3 studies, low-quality evidence; hyphema: RR 0.33, 95% CI 0.12 to 0.94, 4 studies, low-quality evidence). The effect of whether Ex-PRESS prevents hypotony was uncertain (RR 0.92, 95% CI 0.63 to 1.33, 2 studies, very low-quality evidence). All these studies received funding from the device manufacturer.Very low-quality evidence from five studies suggests that use of Ologen compared with trabeculectomy alone is associated with slightly higher IOP at one year (MD 1.40 mm Hg, 95% CI -0.57 to 3.38; 177 eyes). The effect of Ologen on preventing hypotony was uncertain (RR 0.75, 95% CI 0.47 to 1.19, 5 studies, very low-quality evidence). Differences between the two treatment groups for other reported complications also were inconclusive.Low-quality evidence from nine studies suggests that use of amniotic membrane with trabeculectomy may be associated with lower IOP at one year compared with trabeculectomy alone (MD -3.92 mm Hg, 95% CI -5.41 to -2.42; 356 eyes). Low-quality evidence showed that use of amniotic membrane may prevent adverse events and complications, such as hypotony (RR 0.40, 95% CI 0.17 to 0.94, 5 studies, low-quality evidence).The report from the only E-PTFE study (60 eyes) showed no important differences for postoperative IOP at one year (MD -0.44 mm Hg, 95% CI -1.76 to 0.88) between the trabeculectomy + E-PTFE versus the trabeculectomy-alone groups. Hypotony was the only postoperative complication observed less frequently in the E-PTFE group compared to the trabeculectomy-alone group (RR 0.29, 95% CI 0.11 to 0.77).The one Gelfilm study reported uncertainty in the difference in IOP and complication rates between the two groups at one year; no further data were provided in the study report.

AUTHORS' CONCLUSIONS

Overall, the use of devices with standard trabeculectomy may help with greater IOP reduction at one-year follow-up than trabeculectomy alone; however, due to potential biases and imprecision in effect estimates, the quality of evidence is low. When we examined outcomes within subgroups based on the type of device used, our findings suggested that the use of an Ex-PRESS device or an amniotic membrane as an adjunct to trabeculectomy may be slightly more effective in reducing IOP at one year after surgery compared with trabeculectomy alone. The evidence that these devices are as safe as trabeculectomy alone is unclear. Due to various limitations in the design and conduct of the included studies, the applicability of this evidence synthesis to other populations or settings is uncertain. Further research is needed to determine the effectiveness and safety of other devices and in subgroup populations, such as people with different types of glaucoma, of various races and ethnicity, and with different lens types (e.g. phakic, pseudophakic).

Comparison of Efficacy Between Endoscopic Cyclophotocoagulation and Alternative Surgeries in Refractory Glaucoma: A Meta-analysis

Refractory glaucoma refers to uncontrolled intraocular pressure (IOP) despite anti-glaucoma medication and surgical treatment, which remains a challenge to be treated. The objective of this study is to evaluate and statistically compare the clinical efficacy between endoscopic cyclophotocoagulation (ECP) and alternative surgical techniques in the treatment of refractory glaucoma in this article, as a meta-analysis. Data sources are China Biomedical Database (Sinomed, online version), China National Knowledge Infrastructure (CNKI), Cqvip, Wanfang database, and PubMed. The randomized controlled trial (RCT) and case-control study literatures evaluating the clinical efficacy between ECP and other surgical techniques were searched electronically from public databases. The methodology quality of the retrieved articles was evaluated according to the RCT or case-control study criteria. The success rate of treatment, intraocular pressure (IOP) and visual acuity were statistically compared. RevMan 5.3 software was used for the meta-analysis. In total, 6 relevant control studies were selected in this study with a total sampling of 429 cases (429 eyes), including 204 eyes in the ECP group and 225 in the non-ECP group. Meta-analysis demonstrated that the clinical efficacy did not significantly differ between 2 groups (P > 0.05). Postoperative IOP was dramatically reduced in both groups. However, it was difficult to evaluate the combined influence of ECP and non-ECP therapies upon IOP reduction. In conclusion, ECP and non-ECP treatment yielded almost equivalent clinical efficacy in treating refractory glaucoma. The IOP-lowering degree, safety, and incidence of complications remain to be further elucidated by RCTs with a larger sample size.

[Supraciliary microstent for open-angle glaucoma: clinical results of a prospective multicenter study]

PURPOSE

The suprachoroidal CyPass micro-stent is designed to be implanted into the supraciliary space to facilitate aqueous outflow along the uveoscleral pathway in patients with open-angle glaucoma (OAG). This study assessed the safety of micro-stent implantation in patients undergoing cataract surgery.

METHODS

In this multicenter study the CyPass microstent was implanted in patients with OAG undergoing cataract surgery. The implantation was performed using a minimally invasive, conjunctiva-sparing, ab interno intervention. Primary endpoints were safety aspects of the implant, secondary endpoints were the reduction of intraocular pressure (IOP) and topical medication.

RESULTS

There were no severe adverse events during or after surgery in any of the patients. In patients with controlled glaucoma (IOP < 21 mmHg) the average IOP remained constant throughout the 24 month follow-up period but mean medication use decreased from 2.0 at baseline to 1.1 postoperative. In patients with IOP of ≥ 21 mmHg the pressure was reduced by 37 % postoperatively and mean medication decreased from 2.2 at baseline to 1.0.

CONCLUSIONS

The safety profile of combined cataract surgery and CyPass microstent implantation is acceptable and patients also showed a decrease in IOP and medication use.

Electron microscopic evaluation of a gold glaucoma micro shunt after explantation

We present a case of an explanted gold glaucoma micro shunt (GMS Plus) and the subsequent light and electron microscopic analyses. The shunt was implanted in a patient with medically refractive glaucoma. The intraocular pressure (IOP) was stable at 12 mm Hg 6 months postoperatively but spiked to 26 mm Hg 6 months later; membranous growth was visible on the implant gonioscopically. A second gold micro shunt was placed 2 years after the first. The IOP was 7 mm Hg 1 week postoperatively but increased to 23 mm Hg 3 weeks later; similar membranous growth was visible on this implant. One of the shunts was explanted, and light and scanning electron microscopic analyses revealed encapsulation around the shunt exterior and connective tissue invasion of the microstructure. This represents the first electron microscopic analysis of an explanted gold glaucoma micro shunt and the first unequivocal images of the fibrotic pseudo-capsule traversing its microchannels and fenestrations.

FINANCIAL DISCLOSURE

Dr. Ahmed is a consultant to and has received research grants from Solx, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Anatomic and physiologic rationale to be applied in accessing the suprachoroidal space for management of glaucoma

This review examines the anatomic and physiologic rationale for accessing the suprachoroidal space in the management of glaucoma. The potential benefits and limitations of past and present attempts to tap into the intraocular pressure-lowering effects of the suprachoroidal space are highlighted.

FINANCIAL DISCLOSURE

The author has no financial or proprietary interest in any material or method mentioned.

Retrospective analysis of the success and safety of Gold Micro Shunt Implantation in glaucoma

BACKGROUND

To evaluate the success rate and adverse effects of Gold Micro Shunt Plus (GMS+) implantation into the supraciliary space.

METHODS

This retrospective study included 31 eyes of 31 patients diagnosed with severe glaucoma and uncontrolled intraocular pressure (IOP) with implantation of a GMS+ by means of a full-thickness scleral flap. The main outcome measures were surgical failure or success, based on the intraocular pressure and adverse effects. Clinical examination data are reported up to 4 years postoperatively.

RESULTS

Thirty eyes (97%) met one of our criteria for failure. Within a mean of 7.3 ± 7.7 months another surgery was performed because of elevated IOP in 24 of 31 eyes (77%) and because of adverse effects in 2 (6%). The remaining 4 eyes, that met one of our criteria for failure, had an IOP reduction of less than 20% with comparable medication. Six GMS+'s were explanted; because of IOP elevation, 2; rubeosis iridis, 2; and low grade inflammation, 2.

CONCLUSIONS

GMS+ implantation is not an effective method to control IOP in patients with glaucoma, when using our surgical technique. The reason for the found signs of chronic low grade inflammation or rubeosis iridis in 4 eyes (13%) remains unknown and has to be further investigated.

[Minimally invasive iridocorneal angle surgery]

The classical filtration surgery with trabeculectomy or drainage of chamber fluid with episcleral implants is the most effective method for permanent reduction of intraocular pressure to lower and normal levels. Even though both operative procedures are well-established the high efficiency of the method causes potentially dangerous intraoperative as well as interoperative complications with a frequency which cannot be ignored. In the past this led to a search for low complication alternatives with non-penetrating glaucoma surgery (NPGS) and the search is still continuing. Trabecular meshwork surgery in particular with continuous development of new operation techniques steered the focus to a complication-poor and minimally invasive, gonioscopic glaucoma surgery.

Different fibroblast subpopulations of the eye: a therapeutic target to prevent postoperative fibrosis in glaucoma therapy

The aim of this study is the characterization of fibroblasts mainly responsible for fibrosis processes associated with trabeculectomy or microstent implantation for glaucoma therapy. Therefore we isolated human primary fibroblasts from choroidea, sclera, Tenon capsule, and orbital fat tissues. These fibroblast subpopulations were analysed in vitro for expression of the extracellular matrix components which are responsible for postoperative scarring in glaucoma therapy. For scarring the proteins of the collagen family are predominant and so we focused on the expression of collagen I, collagen III and collagen VI in every fibroblast subpopulation. Also, the extracellular matrix protein fibronectin which crosslinks collagen fibres or other extracellular matrix components and cell surfaces, was analyzed. Collagen I, III and VI were prominent in every fibroblast subpopulation. The highest amounts of collagen III were found in hCF and hOF, whereas the signal in hSF and hTF was negligible. Additionally, there is a link between scarring processes and proliferating potential of fibroblasts, in case of microstent implantation triggered through the infiltration of inflammatory cells. Thus we analyzed fibroblast subpopulations for the presence of TGF-β1 which is one of the most important cytokines involved in proliferation processes. TGF-β1 was prominent in all fibroblast subpopulations with lowest expression in hCF cultures. To prevent postoperative fibroblast proliferation we analyzed in vitro the proliferation-inhibitors paclitaxel and mitomycin C which are potential candidates in drug eluting drainage systems on ocular fibroblast subpopulations. These inhibitors arrest fibroblast proliferation and viability, being, however, not very specific and have a cytotoxic potential also on healthy tissues surrounding the microstent outflow area. Significant differences in protein synthesis of fibroblasts subpopulations which could be specific targets for inhibition may help to find out fibroblast specific inhibitors to prevent postoperative scarring and could prevent patients from secondary surgery after microstent implantation.

Morphologic study of the drainage pathway using a tracer after a bypass filtering procedure in rabbit eyes

BACKGROUND AND OBJECTIVE

To study the drainage pathway using a tracer after a modified filtering surgery in rabbit eyes.

MATERIALS AND METHODS

The authors performed trabeculectomy combined with deep sclerectomy on one eye (TS group) and trabeculectomy on the other eye (T group) of 20 rabbits. Cationic ferritin was injected intracamerally just before killing the rabbits at postsurgical week 2, 4, 8, 12, or 24. The opposite side of the surgical site was used as the control. Histologic study was conducted under light microscopy.

RESULTS

In both groups, significantly more intrascleral and episcleral drainage vessels were observed than in the paired controls (P < .001). Intrascleral drainage canals were more often manifested in the TS group than in the T group (P < .05), especially after week 12.

CONCLUSION

Intrascleral and episcleral outflow were the main drainage routes after filtering surgeries in this model. Compared with trabeculectomy, the modified surgery was superior for forming an intrascleral "bleb" and seemed to be better maintained at a later stage.

Modern concepts in antiglaucomatous implant surgery

BACKGROUND

Antiglaucomatous implant surgery is a continously evolving field in glaucoma treatment.

METHODS

A literature search with the terms "glaucoma implant surgery", "aqueous shunts" and "glaucoma drainage devices" was carried out, especially giving prominence to innovative surgical developments in glaucoma implant surgery and to recently established clinical evidence on traditional shunt surgery.

RESULTS

Episcleral glaucoma drainage devices have recently proven their efficacy in large studies. Longterm data about their clinical efficacy and their risk/safety profile are sufficiently available. New antiglaucomatous devices try to target alternative drainage routes, for example trabecular or uveoscleral outflow. Valid longterm data from prospective randomized clinical trials are not available for these devices as yet.

CONCLUSIONS

Although valid data on clinical application of the new glaucoma implants are not available as yet, profound knowledge about their theoretical concept and their practical management is obligatory for all glaucoma clinicians.