Long-term results of up to 12 years of over 700 cases of viscocanalostomy for open-angle glaucoma

Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies.

Differences in the Surgical Outcomes of Glaucoma Surgery in Patients of African Caribbean Descent

PURPOSE

People of African Caribbean Descent (ACD) have a higher prevalence of glaucoma compared to people of European Descent (ED) and there is uncertainty if treatment outcomes are equivalent between the two groups. To assess surgical failure rates comparing ACD with ED focusing on trabeculectomy, aqueous shunt implantation, non-penetrating filtering surgery (NPFS), and minimally invasive glaucoma surgery (MIGS) by performing a systematic review in accordance with the PRISMA guidelines and to determine whether there is any evidence in to show a difference in success rates based on race.

METHODS

A systematic review of articles using the CENTRAL, Ovid MEDLINE, PubMed, EMBASE, and ClinicalTrials.gov databases was completed. Additional studies were identified by contacting clinical experts and searching bibliographies. All retrospective and prospective studies on trabeculectomy, aqueous shunt implantation, NPFS, and MIGS that included at least 20% ACD were included. Two review authors independently screened search results for eligibility and inclusion and extracted the data using pre-determined fields.

RESULTS

A total of 76 studies were identified for inclusion in the review. Glaucoma surgical outcomes in ACD appear to be poorer compared to ED overall, particularly for trabeculectomy. Data on NPFS are limited, but the studies completed thus far demonstrate surprisingly good results for ACD, particularly when compared to ED, who have significantly lower pre-operative IOPs. Evidence from studies investigating aqueous shunts does not suggest that ACD have poorer outcomes than ED. There is not enough data on MIGS to provide a significant conclusion.

CONCLUSION

In a population where trabeculectomy may no longer be the gold standard, sufficiently powered studies assessing surgical outcomes in aqueous shunts, NPFS, and MIGS are needed to guide clinicians.

Glaucoma Treatment Outcomes in Open Angle Glaucoma Patients of African Descent

Open angle glaucoma (OAG), characterized by structural changes to the optic nerve head and retinal nerve fiber layer, is a progressive multifactorial optic neuropathy and a leading cause of irreversible blindness globally. Currently, intraocular pressure is the only modifiable risk factor; however, others have been identified, including genetics and race. Importantly, OAG is much more prevalent in persons of African descent (AD) compared with those of European descent (ED). OAG patients of AD are also known to have a more severe course of the disease, a finding potentially explained by structural and/or vascular differences within eye tissues. In addition, disparities in treatment outcomes have been identified in OAG patients of AD. Specifically, prostaglandin analogues have been suggested to be more effective in patients of AD than in those ED, while beta-adrenergic receptors have been suggested to be less effective, although the evidence is inconsistent. AD has also been identified as a risk factor for trabeculectomy failure while laser trabeculoplasty has been conversely found to be very effective in lowering intraocular pressure in patients of AD. Alternative surgical options, including Ex-Press shunt implantation, viscocanalostomy, and canaloplasty are promising in equivalence but require further research to evaluate disparity in outcome properly. In addition to treatment outcomes, social disparities affecting clinical care also exist for AD persons in the form of reduced adherence, access, and choice. Overall, data suggest the need for properly designed prospective trials with AD populations as a primary focus to identify the potential mechanisms driving disparities in treatment and address overall potential bias in glaucoma management.

Modified suture-assisted canaloplasty in Asians with primary open-angle glaucoma: a prospective study with 12-month follow-up

BACKGROUND

To evaluate the efficacy and safety of modified suture-assisted canaloplasty in Asians with primary open-angle glaucoma (POAG).

METHODS

A prospective, consecutive cases study, evaluating a modified canaloplasty by twisted 6/0 suture was performed on Asian POAG patients. Three modifications of this canaloplasty included opening the Schlemm's canal by viscocanalostomy, circumferential probing by a twisted 6/0 suture and loose suture of the superficial scleral flap. The twisted 6/0 suture was selected as a prober based on characteristical analysis of size and contact measurement as well as chemical composition conducted among 5/0, twisted 6/0 polypropylene sutures and the microcatheter. Success criteria were defined as intraocular pressure (IOP) ≤ 21 mmHg, 18 mmHg, 15 mmHg, and ≥ 20% reduction without (complete success) or with medications (qualified success). Efficacy was assessed by the success rate of circumferential catheterization, IOP values, the success rate of the surgery, the number of IOP-lowering medications, best-corrected vision acuity (BCVA), cup-to-disc ratio (C/D), and mean deviation (MD). Safety was evaluated by adverse events.

RESULTS

Forty eyes from 40 consecutive patients were included with a mean follow-up of 14.8 ± 3.0 months. Circumferential catheterization was successfully conducted in 36 eyes (90%). Mean IOP decreased from 26.2 ± 6.9 mmHg to 14.5 ± 2.7 mmHg at 12 months postoperatively. While medication numbers were reduced from 3.2 ± 0.6 to 0.5 ± 0.8 at month 12 (both p < 0.001). Qualified success rate was 97.2% [95% confidence interval (CI) 0.92-1.03], 86.1% (95% CI 0.74-0.98) and 66.7% (95% CI 0.51-0.83) at 12 months with three criteria. BCVA, C/D and MD did not show progression at 1-year follow-up (p > 0.05). Age, baseline IOP, and spherical equivalent negatively influenced the success rate significantly (all p < 0.05). Adverse events included hyphema (30.6%), IOP spike > 25 mmHg (8.3%), and peripheral synechia to the trabecular-Descemet's membrane (2.7%).

CONCLUSION

Twisted 6/0 suture can be an ideal material for cannulation. Modified suture-assisted canaloplasty is an effective, safe alternative with a cost-efficient feature for patients with POAG, especially in developing countries.

TRIAL REGISTRATION

This trial was registered in the Chinese Clinical Trial Registry ( ChiCTR1900028618 , 29/12/2019).

Long-term Results of Nd:YAG Goniopuncture on Viscocanalostomy and Phacoviscocanalostomy

PRCIS

Laser goniopuncture (LGP) is an effective outpatient procedure which has been shown to maintain reduced intraocular pressure (IOP) 5 years following initial laser treatment in patients who have had viscocanalostomy (VC) (with or without phacoemulsification).

PURPOSE

The purpose of this study was to establish the long term (5 y) efficacy of neodymium-doped:yttrium aluminum-garnet LGP to lower IOP following VC or phacoviscocanalostomy (PVC) in patients with glaucoma.

PATIENTS AND METHODS

This retrospective study analyzed patients who underwent LGP following VC±phacoemulsification between 2009 and 2012 at the Stanley Eye Unit in Abergele. Reason for further intervention included either increasing IOP outside target range or worsening visual fields. Statistical analyses were performed comparing pregoniopucture values to those taken up to 5 years later.

RESULTS

Of the 620 VC and PVC procedures performed between 2009 and 2012, 218 eyes underwent LGP after a mean of 25 months [95% confidence interval (CI): 22.58 to 27.41] following surgery. Patients having a PVC had a longer mean time to goniopuncture compared with those who were phakic and had VC only (P<0.001). Immediately following goniopuncture IOP dropped, and a statistically significant reduction persisted at 5 year follow-up (P<0.001). Goniopuncture reduced IOP significantly from a pretreatment value of 21 to 15 mm Hg over 5 years (95% CI) (χ2F(4)=119.1, P<0.001). In total, 154 eyes (71%) were commenced on IOP-lowering medication at a mean of 14 months (95% CI: 12 to 17). At 5 years, successful IOP control was achieved in 73% (49 of 67) of eyes. There was no difference found between type of surgery and successful pressure control at 5 years (χ2(1)=2.00, P=0.16).

CONCLUSION

LGP is an effective procedure which maintains a statistically significant reduction in IOP in the long term.

Aqueous outflow regulation - 21st century concepts

We propose an integrated model of aqueous outflow control that employs a pump-conduit system in this article. Our model exploits accepted physiologic regulatory mechanisms such as those of the arterial, venous, and lymphatic systems. Here, we also provide a framework for developing novel diagnostic and therapeutic strategies to improve glaucoma patient care. In the model, the trabecular meshwork distends and recoils in response to continuous physiologic IOP transients like the ocular pulse, blinking, and eye movement. The elasticity of the trabecular meshwork determines cyclic volume changes in Schlemm's canal (SC). Tube-like SC inlet valves provide aqueous entry into the canal, and outlet valve leaflets at collector channels control aqueous exit from SC. Connections between the pressure-sensing trabecular meshwork and the outlet valve leaflets dynamically control flow from SC. Normal function requires regulation of the trabecular meshwork properties that determine distention and recoil. The aqueous pump-conduit provides short-term pressure control by varying stroke volume in response to pressure changes. Modulating TM constituents that regulate stroke volume provides long-term control. The aqueous outflow pump fails in glaucoma due to the loss of trabecular tissue elastance, as well as alterations in ciliary body tension. These processes lead to SC wall apposition and loss of motion. Visible evidence of pump failure includes a lack of pulsatile aqueous discharge into aqueous veins and reduced ability to reflux blood into SC. These alterations in the functional properties are challenging to monitor clinically. Phase-sensitive OCT now permits noninvasive, quantitative measurement of pulse-dependent TM motion in humans. This proposed conceptual model and related techniques offer a novel framework for understanding mechanisms, improving management, and development of therapeutic options for glaucoma.

The Efficacy of Ab Externo Canaloplasty by Using a Nonabsorbable Suture and No Viscoelastics; IOP Results, Intraoperative and Early Complication Rates within 6-Month Follow-Up Period

BACKGROUND

To report the efficacy of ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification in terms of mean intraocular pressure (IOP), medication reduction, and intra- and postoperative complication rates as well as additional glaucoma surgery.

PATIENTS AND METHODS

Forty-eight patients with primary open-angle glaucoma (POAG) and 50 eyes were divided into two groups according to the operation performed (Group A canaloplasty, n = 34 and Group B canaloplasty combined with phaco, n = 16), respectively. The success criteria were evaluated between three IOP ranges: a) IOP ≤ 16 mmHg, b) ≤ 18 mmHg, and c) ≤ 21 mmHg. Complete success was considered the percentage of eyes reaching these goals with no medication and qualified success with or without medication. Groups A and B were compared with the Kaplan-Meier test. Mean IOP and medication reduction as well as additional glaucoma surgery were also evaluated. The follow-up time was 6 months. Statistical importance was given at p < 0.05.

RESULTS

Fail rate and intraoperative conversion of canaloplasty to other surgery (trabeculotomy due to extensive cheese-wiring) accounted for 12% (6 eyes), while a mandatory usage of the iTrack 250A microcatheter to successfully overcome intracanalicular bridging of the Schlemm's canal accounted for 20% (10 eyes). The most common early postoperative complications in both groups were hyphema, cheese wiring, and transient IOP rising. The mean IOP in Group A reduced from 23.67 ± 6.06 mmHg to 13.35 ± 4.23 mmHg and in Group B, it reduced from 23.55 ± 6.19 mmHg to 12.75 ± 1.5 mmHg at 6 months (p < 0.001). Group A's absolute success rates accounted for a) 44%, b) 47.1%, and c) 52.9% in comparison to Group B [a) 50%, b) 50%, and c) 56.3%] at 6 months (p < 0.05). Qualified success with or without medication showed no statistical differences between the groups. The mean medication reduction was significantly lower (p < 0.001) in both groups (Group A from baseline 3.2 ± 1.23 to 0.95 ± 1.35 and Group B from 3.12 ± 0.88 to 1.12 ± 0.75 at 6 months, respectively). Five eyes (10%) required additional glaucoma surgery.

CONCLUSIONS

Ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification seems to lower the mean IOP and medication sufficiently. However, they pose a greater surgical challenge and intraoperative complication rate. Additional glaucoma surgery or medication following both procedures may be necessary to achieve an optimal target IOP.

Isolation and characterization of novel primary cells from the human distal outflow pathway

Ocular hypertension occurs due to increased resistance to aqueous humor removal through the conventional outflow pathway. Unlike the proximal region of the conventional outflow pathway, the distal region has not been well studied, mostly due to lack of model systems. Here we describe isolation and characterization of human primary vascular distal outflow pathway (VDOP) cells from the distal region of the conventional outflow pathway. Tissue from the distal region was isolated from human corneo-scleral rims, digested with collagenase type I (100 U/ml) and placed on gelatin coated plates to allow cellular growth in Dulbecco's Modified Eagle's Medium (low glucose) containing fetal bovine serum and antibiotic/antimycotic. VDOP cells showed consistent proliferation for up to 7 passages, retained endothelial-like nature of the parent tissues and showed a unique marker phenotype of Lectin+VEGFR2-CD34-NG2- that was distinct from neighboring trabecular meshwork (Lectin+VEGFR2-CD34-NG2+) and Schlemm's canal (Lectin+VEGFR2+CD34+NG2+) cells. Dexamethasone treated VDOP cells did not express myocilin and did not form cross-linked actin networks, in contrast to trabecular meshwork cells. These data show that VDOP cells are unique to the distal outflow region and can be used as a viable in vitro model system to understand the biology of the distal outflow pathway and intraocular pressure regulation.

Personalising surgical treatments for glaucoma patients

Surgical treatments for glaucoma have relied for decades on traditional filtering surgery such as trabeculectomy and, in more challenging cases, tubes. Antifibrotics were introduced to improve surgical success in patients at increased risk of failure but have been shown to be linked to a greater incidence of complications, some being potentially vision-threatening. As our understanding of glaucoma and its early diagnosis have improved, a more individualised management has been suggested. Recently the term "precision medicine" has emerged as a new concept of an individualised approach to disease management incorporating a wide range of individual data in the choice of therapeutic modalities. For glaucoma surgery, this involves evaluation of the right timing, individual risk factors, targeting the correct anatomical and functional outflow pathways and appropriate prevention of scarring. As a consequence, there is an obvious need for better knowledge of anatomical and functional pathways and for more individualised surgical approaches with new, less invasive and safer techniques allowing for earlier intervention. With the recent advent of minimally invasive glaucoma surgery (MIGS) a large number of novel devices have been introduced targeting potential new sites of the outflow pathway for lowering intraocular pressure (IOP). Their popularity is growing in view of the relative surgical simplicity and apparent lack of serious side effects. However, these new surgical techniques are still in an era of early experiences, short follow-up and lack of evidence of their superiority in safety and cost-effectiveness over the traditional methods. Each year several new devices are introduced while others are withdrawn from the market. Glaucoma continues to be the primary cause of irreversible blindness worldwide and access to safe and efficacious treatment is a serious problem, particularly in the emerging world where the burden of glaucoma-related blindness is important and concerning. Early diagnosis, individualised treatment and, very importantly, safe surgical management should be the hallmarks of glaucoma treatment. However, there is still need for a better understanding of the disease, its onset and progression, the functional and structural elements of the outflow pathways in relation to the new devices as well as their long-term IOP-lowering efficacy and safety. This review discusses current knowledge and the future need for personalised glaucoma surgery.

Modified viscocanalostomy in the Chinese population with open angle glaucoma: a 10-year follow-up results

AIM

To study the long-term efficacy and safety of modified viscocanalostomy in Chinese people with open angle glaucoma (OAG).

METHODS

This retrospective study included a total of 100 eyes from 100 Chinese patients with medically uncontrolled OAG. All the patients underwent modified viscocanalostomy with injection of viscoelastic material in the surgically created ostia of Schlemm's canal (SC). The modifications included peeling of the inner wall of SC and the juxtacanalicular meshwork, use of mitomycin C, and loosely suturing the superficial scleral flap. Intraocular pressure (IOP), visual acuity, number of medications, laser goniopuncture data and complications were recorded. The definition of complete (qualified) success was an IOP equal to or lower than 21, 18, 16 mm Hg without (with or without) anti-glaucoma medications.

RESULTS

The mean IOP was 33.5±9.9 mm Hg before surgery, 15.2±3.6 mm Hg (mean IOP reduction of 51%) at 5y after surgery, and 15.6±2.8 mm Hg (mean IOP reduction of 49.9%) at 10y after surgery (P<0.001). The number of anti-glaucoma medications dropped from 2.39±0.5 preoperatively to 0.47±0.8 at 5y and 0.67±0.8 at 10y postoperatively (P<0.001). The follow-up period was 104.5±37.0mo. The qualified success rate for an IOP of 21, 18 or 16 mm Hg or less was 84% [95% confidence interval (CI): 0.80-0.88], 73% (95%CI: 0.68-0.78), and 59% (95%CI: 0.52-0.66) after 5y, and 80% (95%CI: 0.76-0.84), 69% (95%CI: 0.64-0.74), 51% (95%CI: 0.44-0.58) after 10y, respectively. There was a relationship between age, preoperative IOP and success rate (P<0.01, P<0.05). A total of 31 eyes (31.3%) in 31 patients underwent laser goniopuncture, decreasing the IOP from 22.9±4.3 mm Hg to 16.3±2.5 mm Hg (P<0.01). Neither blebitis nor endophthalmitis occurred.

CONCLUSION

Modified viscocanalostomy could be performed to lower IOP, decrease multiple anti-glaucoma drops use as well. It's a safe procedure with less complications over 10y in Chinese individuals with OAG.

Comparison of performance between two microcatheter systems in ab externo canaloplasty: A retrospective comparison study

Purpose:

To compare the performance of two different microcatheter systems, iTrack™ 250A and Glaucolight, in ab externo canaloplasty in three major categories: intraocular pressure reduction, drug therapy reintroduction, and evaluation of viscodilation over distension of the inner wall of Schlemm’s canal.

Methods:

A total of 56 and 46 eyes from different glaucoma types underwent ab externo canaloplasty using two different microcatheter systems. Group formation was made according to microcatheter system used. Kaplan–Meier test was performed for drug therapy reintroduction in relation to the two microcatheters. Tests of between-subject effects in two-way analysis of variance evaluated the efficacy of the two microcatheters and their features in relation to intraocular pressure reduction.

Results:

Kaplan–Meier test was not statistically significant (p = 0.20) regardless of microcatheter system. Tests of between-subject effects in relation to intraocular pressure reduction was not statistically different between the two microcatheters (p = 0.26) or between microcatheter and follow-up (p = 0.90). Intraocular pressure reduction in different glaucoma type was statistically significant during the follow-up period and glaucoma types showed different results between them in relation to follow-up (p < 0.001 and p = 0.002, respectively), but the pairwise comparison was not statistically important (p = 0.42). Intraocular pressure reduction was better in pseudophakic eyes in comparison with phakic eyes (p = 0.03), but the selection of microcatheter seemed not to affect this result (p = 0.11 and p = 0.32, respectively).

Conclusion:

Both microcatheter systems performed equal in terms of intraocular pressure reduction. Drug therapy reintroduction was not affected by the selection of the two microcatheters. Different types of glaucoma responded different to canaloplasty. Pseudophakic eyes responded better to treatment than phakic eyes, but the microcatheter selection seemed not affect this result.

Stegmann Canal Expander for canaloplasty: A novel technique

Introduction:

The concept of canaloplasty is to increase aqueous egress through all structures that control the aqueous outflow, such as the trabecular meshwork, Schlemm’s canal, and collector channels, by viscomodulation and by placing of a suture stent into the canal. Clinical studies show canaloplasty to be safe and efficient in lowering the intraocular pressure; however, proper knotting of the tensioning suture is technically challenging and even impossible if circumferential cannulation cannot be achieved; furthermore, protrusion of the suture stent is a potential lifelong risk.

Methods:

The specific design of the Stegmann Canal Expander allows a permanent expansion of the canal and distension of the trabecular meshwork. Two expanders are implanted on either side of the surgically created ostium of Schlemm’s canal to treat half of the circumferential outflow system. This article describes the technique step by step, provides the clinician with surgical pearls, and highlights the management of adverse events.

Results:

Technically, implantation of the Stegmann Canal Expander is simple and does not require a long learning curve, compared to placing and knotting a tensioning suture. Most issues are related to the two-flap dissection technique (deep sclerectomy technique) and not to implantation of the Stegmann Canal Expander. Intraocular pressure reduction without medications to the low teens can be achieved.

Conclusions:

The Stegmann Canal Expander is a novel micro-device that has the potential to make canaloplasty a simplified, more controlled, and reproducible surgical procedure.

Effect of primary Phacoviscocanalostomy/ Viscocanalostomy on intraocular pressure of normal tension glaucoma patients: 3-year results

BACKGROUND

The objective of this study was to evaluate the efficacy of Viscocanalostomy/Phacoviscocanalostomy (VC/PVC) in lowering intraocular pressure (IOP) in Normal Tension Glaucoma (NTG) patients.

METHODS

Retrospective electronic database review of patients who underwent VC/PVC for NTG between December 2009 and November 2011 at Stanley eye unit in Abergele Hospital. Goldmann applanation tonometry (GAT) was used for all IOP measurements which were taken at the time of listing for surgery and at 1 day, 1 week, 1 month, then 3-monthly up to 1 year, then half-yearly up to 3 years post operatively. Statistical analysis was performed using unpaired t-test. A P value of <0.05 was accepted as the level of significance.

RESULTS

Operations were performed on 94 eyes from 67 patients over the study period. The mean age at the time of surgery was 76.4 years. Pre-operative IOP was 17.75 ± 2.19 mmHg (range 12-21 mmHg). 3 year follow-up showed a mean IOP of 13.41 ± 2.22 mmHg (range 8-18 mmHg). By year 3, 17 patients needed laser goniopuncture and 25 patients needed antiglaucoma drops. IOP was reduced by 24.4% at 3 years post-surgery, which was statistically significant (p < 0.0001).

CONCLUSIONS

From our results, which show a 24.5% reduction in IOP at 3 years with 12% complication rate, we propose that a logical surgical management for NTG patients would be viscocanalostomy, thereby keeping trabeculectomy as an alternative.

Canaloplasty with Stegmann Canal Expander for primary open-angle glaucoma: two-year clinical results

PURPOSE

To examine longer-term postsurgical safety and efficacy of a new expander for Schlemm's canal.

METHODS

In a non-comparative, prospective study, 42 White patients with medically uncontrolled primary open-angle glaucoma (POAG) underwent primary canaloplasty with >2-year follow-up. The bleb-independent procedure comprised catheter-assisted canaloplasty and implantation of two Stegmann Canal Expanders to maintain trabecular distension and canal patency over 180°. Intraocular pressure (IOP), glaucoma medication use and complications were assessed.

RESULTS

Mean IOP was 26.8 ± 5.6 mmHg presurgery, 12.8 ± 1.5 mmHg at 6 months, 13.2 ± 1.2 mmHg at 12 months and 13.3 ± 2.5 mmHg at 24 months (p < 0.001). Rate of complete success, defined as IOP ≤21, ≤18 and ≤16 mmHg and a ≥ 30% IOP reduction, was 85% (95% CI: 0.76-0.95), 85% (0.76-0.95) and 82% (0.70-0.96) at 12 months and 83% (0.73-0.94), 80% (0.70-0.92) and 80% (0.70-0.92) at 24 months. Preoperative factors were not significant predictors of ≤16 mmHg IOP reduction: IOP (hazard ratio [HR]: 0.68; 95% CI: 0.44-1.04; p = 0.08), mean visual defect (1.06; 0.90-1.20; p = 0.47), number of medications (0.59; 0.17-2.14; p = 0.42) and age (0.96; 0.87-1.13; p = 0.41). Number of medications dropped from 2.8 ± 0.4 presurgery to 0.2 ± 0.5 postsurgery (p < 0.001). Mean preoperative best-corrected visual acuity was 0.19 ± SD 0.21 (range: 0-1.6), and logMAR was similar to 0.23 ± 0.16 (range: 0-1.6; p = 0.42) after a mean follow-up of 27.4 months. Complications included peripheral Descemet's membrane detachment (7.2%) and trimming of the expander (4.7%) during surgery, and transient microhyphaema (23.8%) and IOP elevation (7.2%) postsurgery.

CONCLUSION

Canaloplasty with the Stegmann Canal Expander was a safe and effective procedure to reduce IOP in White patients with moderate to advanced POAG.

Viscocanalostomy combined with trabeculotomy and mitomycin C in the treatment of primary congenital glaucoma

AIM

To evaluate the long-term outcome of viscocanalostomy combined with trabeculotomy and mitomycin C in the treatment of primary congenital glaucoma.

METHODS

This is a retrospective study. Forty-two eyes of 26 patients with primary congenital glaucoma were enrolled. Intraocular pressure (IOP), corneal diameter (mm) and cup/disc (C/D) were measured before and after the surgery respectively. Follow-up period was 30mo.

RESULTS

The mean preoperative IOP was 30.6±7.35 mm Hg. Of the 42 eyes, 2 eyes were required conversion to trabeculectomy for the absence of Schlemm's canal. Of remained 40 eyes, 38 eyes (95%) achieved successful IOP control. The average postoperative IOP was 11.69±4.18 mm Hg at 12mo. The mean reduction was 18.91 mm Hg (P<0.0001). Eighteen (75%) eyes presented a reduction in corneal diameter, and 25 (62.5%) eyes presented a C/D ratio reversal after the surgery. There was no serious complication in any patients over the follow-up period.

CONCLUSION

Viscocanalostomy combined with trabeculotomy and mitomycin C is useful in the management of primary congenital glaucoma.

Aqueous outflow - A continuum from trabecular meshwork to episcleral veins

In glaucoma, lowered intraocular pressure (IOP) confers neuroprotection. Elevated IOP characterizes glaucoma and arises from impaired aqueous humor (AH) outflow. Increased resistance in the trabecular meshwork (TM), a filter-like structure essential to regulate AH outflow, may result in the impaired outflow. Flow through the 360° circumference of TM structures may be non-uniform, divided into high and low flow regions, termed as segmental. After flowing through the TM, AH enters Schlemm's canal (SC), which expresses both blood and lymphatic markers; AH then passes into collector channel entrances (CCE) along the SC external well. From the CCE, AH enters a deep scleral plexus (DSP) of vessels that typically run parallel to SC. From the DSP, intrascleral collector vessels run radially to the scleral surface to connect with AH containing vessels called aqueous veins to discharge AH to blood-containing episcleral veins. However, the molecular mechanisms that maintain homeostatic properties of endothelial cells along the pathways are not well understood. How these molecular events change during aging and in glaucoma pathology remain unresolved. In this review, we propose mechanistic possibilities to explain the continuum of AH outflow control, which originates at the TM and extends through collector channels to the episcleral veins.

Laser intervention on trabeculo-Descemet's membrane after resistant viscocanalostomy: Selective 532 nm gonioreconditioning or conventional 1064 nm neodymium-doped yttrium aluminum garnet laser goniopuncture?

Purpose:

To compare the results of conventional 1064 nm neodymium-doped yttrium-aluminum garnet laser goniopuncture (Nd:YAG-GP) and selective 532 nm Nd:YAG laser (selective laser trabeculoplasty [SLT]) gonioreconditioning (GR) on trabeculo-Descemet's membrane in eyes resistant to viscocanalostomy surgery.

Methods:

Thirty-eight eyes of 35 patients who underwent laser procedure after successful viscocanalostomy surgery were included in the study. When postoperative intraocular pressure (IOP) was above the individual target, the eyes were scheduled for laser procedure. Nineteen eyes underwent 532 nm SLT-GR (Group 1), and the remaining 19 eyes underwent conventional 1064 nm Nd:YAG-GP (Group 2). IOPs before and after laser (1 week, 1 month, 3 months, 6 months, 1 year, and last visit), follow-up periods, number of glaucoma medications, and complications were recorded for both groups.

Results:

Mean times from surgery to laser procedures were 17.3 ± 9.6 months in Group 1 and 13.0 ± 11.4 months in Group 2. Mean IOPs before laser procedures were 21.2 ± 1.7 mmHg in Group 1 and 22.8 ± 1.9 mmHg in Group 2 (P = 0.454). Postlaser IOP measurements of Group 1 were 12.1 ± 3.4 mmHg and 13.8 ± 1.7 mmHg in the 1^st week and last visit, respectively; in Group 2, these measurements were 13.6 ± 3.7 mmHg and 14.9 ± 4.8 mmHg, respectively. There were statistically significant differences (P < 0.001) in IOP reduction at all visits in both groups; the results of the two groups were similar (P > 0.05). Mean follow-up was 16.6 ± 6.4 months after SLT-GR and 18.9 ± 11.2 months after Nd:YAG-GP.

Conclusions:

While conventional Nd:YAG-GP and SLT-GR, a novel procedure, are both effective choices in eyes resistant to viscocanalostomy, there are fewer complications with SLT-GR. SLT-GR can be an alternative to conventional Nd:YAG-GP.

Canaloplasty in patients with uveitic glaucoma: a pilot study

PURPOSE

Glaucoma is a common vision-threatening complication of uveitis. We investigated the outcome of canaloplasty in patients with chronic uveitis and uncontrolled secondary glaucoma.

METHODS

This was a retrospective study of 12 patients with medically uncontrolled secondary glaucoma who underwent canaloplasty (14 treated eyes), with follow-up of ≥ 24 months. The primary outcome measure was complete and qualified (requirement for anti-glaucomatous medication) surgical success rates, as determined by a reduction in intraocular pressure (IOP) and the need for anti-glaucomatous medication. Secondary outcome measures were uveitis activity, best-corrected visual acuity (BCVA), vision-threatening complications, and secondary glaucoma surgery.

RESULTS

Canaloplasty resulted in a significant IOP reduction, from a mean preoperative baseline level of 27.1 ± 12.3 mmHg to a mean of 14.5 ± 4.3 mmHg (p = 0.01) at 24 months. Complete success (limit of 15 mmHg) was achieved in six patients and qualified success in one patient. However, failure was noted in five patients, two of whom required additional glaucoma surgery. Topical anti-glaucomatous medications were reduced from 2.7 ± 1.2 (mean ± SD) at baseline to 0.6 ± 1.2 at 24 months (p = 0.007). Uveitis activity did not increase after surgery. BCVA was not reduced; cataract progressed in two patients.

CONCLUSION

At 2-year follow-up, overall success rate was 58 % (IOP ≤ 15 with or without medication), and surgery failed in 5 eyes, 2 eyes requiring additional glaucoma surgery. No harmful complications or worsening of uveitis activity were noted.