Complications Common to Nonpenetrating Surgeries

2013 ◽  
Author(s):  
Andrew C. Crichton
Keyword(s):  
Glaucoma Surgery ◽  
Outer Wall ◽  
Glaucoma Drainage Device ◽  
Deep Sclerectomy ◽  
Success Rates ◽  
Schlemm’S Canal ◽  
Schlemm's Canal ◽  
Descemet's Membrane ◽  
Descemet’S Membrane ◽  
Controlled Flow

Nonpenetrating glaucoma surgery encompasses techniques that involve a deep dissection to the level of Descemet’s membrane, allowing aqueous seepage. The major techniques covered by the term “nonpenetrating surgery” are deep sclerectomy with or without implant and viscocanalostomy. In large meta-analyses comparing nonpenetrating procedures to trabeculectomy, trabeculectomy resulted in lower intraocular pressures (IOP) but a higher risk of postoperative complications. Although nonpenetrating surgery is successful in lowering IOP, the amount of IOP lowering is typically not as low as can be achieved with trabeculectomy. Consequently, patient selection with regard to the target IOP is important in the decision of whether or not to perform a nonpenetrating procedure. The goal of nonpenetrating procedures is to lower IOP with fewer complications than are seen with trabeculectomy. The complications that can occur can be easily understood and predicted by an understanding of the techniques and modifications, as well as knowledge and mechanisms of the adjustments that can be used postoperatively to enhance success. After appropriate anesthetic, the techniques involve a deep dissection in the sclera to the limbus. In the case of deep sclerectomy, after the initial half-thickness flap is fashioned, a second deeper flap is created and excised. This dissection is taken to the level of Descemet’s membrane, allowing controlled flow of aqueous. A fine forceps may be used to strip the outer wall of Schlemm’s canal, further enhancing the flow. The space created by the excision can then be filled with an implant, such as collagen (AquaFlow™ Collagen Glaucoma Drainage Device; STAAR® Surgical Company, Monrovia, California) or hyaluronate (SK Gel®; Corneal Laboratories, Paris, France). For viscocanalostomy, Schlemm’s canal is identified and dilated by using viscoelastic. With deep sclerectomy, intraoperative or postoperative antimetabolites may be used to try to increase success rates by limiting the inflammatory response. Goniopuncture to the Descemet’s window is often required postoperatively (in up to 67% of cases) to enhance flow and lower IOP. The available evidence on complications of nonpenetrating glaucoma surgery is relatively sparse and may be challenging to interpret. Comparative studies between trabeculectomy and nonpenetrating surgery would seem to show fewer complications in the nonpenetrating group.

scholarly journals Comparison of Efficacy between 120° and 180° Schlemm’s Canal Incision Microhook Ab Interno Trabeculotomy

2021 ◽  
Vol 10 (14) ◽  
pp. 3181
Author(s):  
Naoki Okada ◽  
Kazuyuki Hirooka ◽  
Hiromitsu Onoe ◽  
Yumiko Murakami ◽  
Hideaki Okumichi ◽  
...  
Keyword(s):  
Surgical Outcomes ◽  
Open Angle Glaucoma ◽  
Case Series ◽  
Glaucoma Surgery ◽  
Success Rates ◽  
Schlemm’S Canal ◽  
Schlemm's Canal ◽  
Kaplan Meier ◽  
The Mean ◽  
Ab Interno

We compared surgical outcomes in patients with either primary open-angle glaucoma or exfoliation glaucoma after undergoing combined phacoemulsification with either a 120° or 180° incision during a Schlemm’s canal microhook ab interno trabeculotomy (μLOT-Phaco). This retrospective comparative case series examined 52 μLOT-Phaco eyes that underwent surgery between September 2017 and December 2020. Surgical qualified success was defined as an intraocular pressure (IOP) of ≤20 mmHg, ≥20% IOP reduction with IOP-lowering medications, and no additional glaucoma surgery. Success rates were evaluated by Kaplan-Meier survival analysis. The number of postoperative IOP-lowering medications and occurrence of complications were also assessed. Mean preoperative IOP in the 120° group was 16.9 ± 7.6 mmHg, which significantly decreased to 10.9 ± 2.7 mmHg (p < 0.01) and 11.1 ± 3.1 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.8 ± 1.4 to 1.4 ± 1.4 (p < 0.01) at 24 months. Mean preoperative IOP in the 180° group was 17.1 ± 7.0 mmHg, which significantly decreased to 12.1 ± 3.2 mmHg (p = 0.02) and 12.9 ± 1.4 mmHg (p = 0.01) at 12 and 24 months, respectively. The mean number of preoperative IOP-lowering medications significantly decreased from 2.9 ± 1.2 to 1.4 ± 1.5 (p < 0.01) at 24 months. The probability of qualified success at 24 months in the 120° and 180° groups was 50.4% and 54.6%, respectively (p = 0.58). There was no difference observed for hyphema formation or IOP spikes. Surgical outcomes were not significantly different between the 120° and 180° incisions in Schlemm’s canal.

Complications Specifically Related to Canaloplasty Surgery

2013 ◽  
Author(s):  
Richard A. Lewis
Keyword(s):  
Open Angle Glaucoma ◽  
Filtering Surgery ◽  
Open Angle ◽  
Schlemm’S Canal ◽  
Scleral Flap ◽  
Schlemm's Canal ◽  
Collector System ◽  
Descemet's Membrane ◽  
Descemet’S Membrane ◽  
Aqueous Outflow

Canaloplasty is a surgical approach for patients with open-angle glaucoma. The objective of the procedure is to enhance circumferential outflow of aqueous from Schlemm’s canal to the collector system, improving outflow without creating a filtering bleb. In the procedure, a microcatheter is threaded into the canal using a standard nonpenetrating approach and then passed for 360 degrees. A polypropylene suture is attached to the catheter. The catheter is then retracted 360 degrees during which time viscodilation is performed. The suture remains in the canal, and the ends of the suture are tied together to place constant tension upon the trabecular meshwork (TM). Theoretically, the tension results in opening of the TM, improving outflow and lowering intraocular pressure (IOP). The procedure has increased in popularity and may be a valuable option for patients with open-angle glaucoma who might be at high risk for filtering surgery complications, such as contact lens wearers, patients on blood thinners, and those patients who already failed filtering surgery in the other eye. With the increased popularity of canaloplasty, knowing how to prevent and manage complications of this procedure are crucial skills for today’s glaucoma surgeon. The notion of enhancing circumferential outflow arose from studies of an earlier nonpenetrating procedure, viscocanalostomy (see Chapter 52). In this procedure, a Descemet’s membrane window is created under a scleral flap, and the outflow system is dilated with viscoelastic for 1–2 clock hours. However, in canaloplasty, 360-degree viscodilation is performed, and a tensioning suture is left in Schlemm’s canal to promote canal distension and aqueous outflow. Passing the microcatheter and completing a successful canaloplasty requires specific steps and careful attention to detail. The procedure may be performed under local, regional, or general anesthesia. Fixation of the globe is the first step, using either a corneal or rectus suture. Then, a half-thickness, 4 mm limbus-based scleral flap is created, followed by a deeper scleral flap, which unroofs the canal. The dissection is then taken forward onto Descemet’s membrane to allow for creation of a Descemet’s window, and the deep flap is excised. Schlemm’s canal is next catheterized 360 degrees.

Descemet’s Membrane Detachment

2013 ◽  
Author(s):  
Malik Y. Kahook
Keyword(s):  
Surgical Intervention ◽  
Corneal Stroma ◽  
Corneal Edema ◽  
Glaucoma Surgery ◽  
Bullous Keratopathy ◽  
Descemet’S Membrane Detachment ◽  
Descemet's Membrane ◽  
Central Regions ◽  
Descemet’S Membrane ◽  
Mechanical Manipulation

Corneal injury resulting from glaucoma surgery has been well described. Causes of injury can range from direct mechanical manipulation to the often more subtle pharmacologically induced injuries that occur with use of antifibrotic medications. Descemet’s membrane detachment (DMD) occurs uncommonly during or after intraocular surgery and has been linked with a variety of procedures ranging from simple clear cornea cataract extraction to deep lamellar keratoplasty. The corneal endothelium, which rests upon Descemet’s membrane, functions as a pump to keep the stroma from becoming swollen. Therefore, DMD results in focal corneal edema and possibly bullous keratopathy. If detachment of Descemet’s membrane extends far enough centrally, visual acuity may become sufficiently compromised to necessitate corneal transplantation surgery (either full-thickness penetrating keratoplasty [PKP] or Descemet’s stripping with automated endothelial keratoplasty [DSAEK]). In glaucoma surgery, DMD often results from the mechanical manipulation that occurs with creation of the cornealtrabecular meshwork opening. Knowing how to accurately diagnose and treat DMD can prevent disastrous consequences and preserve vision. Mackool and Holtz proposed separating DMD into 2 categories, planar and nonplanar, depending on the distance of separation between Descemet’s membrane and the posterior corneal stroma. Planar DMD involves less than 1 mm separation of Descemet’s membrane from the corneal stroma and may be limited to the periphery or extend from the periphery to central regions. Nonplanar DMD involves greater than 1 mm separation of Descemet’s membrane from the corneal stroma and may also be categorized as limited to the periphery or extending to central regions. The significance of this classification was the belief that planar DMD was more likely to spontaneously resolve while nonplanar DMD required surgical intervention. Assia and colleagues also split DMD into 2 categories: DMD with scrolling of tissue and DMD without scrolling of tissue. They believed this classification more accurately described potential for spontaneous resolution in that nonscrolled DMD was more likely to resolve without surgical intervention, even if its location was >1mm from the posterior corneal stroma. While useful as a general guide, these classification systems are not foolproof, and each case of DMD should be viewed independently.

Viscocanalostomy: A Pilot Study

1998 ◽  
Vol 8 (2) ◽  
pp. 57-61 ◽  
Author(s):  
R.G. Carassa ◽  
P. Bettin ◽  
M. Fiori ◽  
R. Brancato
Keyword(s):  
Intraoperative Complications ◽  
Glaucoma Surgery ◽  
Ophthalmological Examination ◽  
Schlemm’S Canal ◽  
Short Term ◽  
Term Study ◽  
Schlemm's Canal ◽  
Short Term Study ◽  
A Prospective Study

Purpose Viscocanalostomy is a new, non-penetrating procedure for glaucoma surgery. We started a prospective study to assess the effectiveness and safety of the operation. Materials and methods Up to March 1998 we enrolled 33 patients (33 eyes) suffering from glaucoma, uncontrolled despite maximum medical therapy, who underwent viscocanalostomy according to Stegmann's technique. A complete ophthalmological examination was performed the day before surgery and on days 1 and 7 postoperatively. Further visits were scheduled at months 1, 3, 6 and 12. Results In four eyes Schlemm's canal was either missed or not deroofed properly, and the procedure was converted into simple trabeculectomy. After a mean follow-up of 3.0±2.6 months (range 1–10), success defined as IOP > 2 and < 21 mmHg with no medication was obtained in 86.2% of the cases (25/29); 23 out of 29 eyes (79.3%) had IOP > 2 and < 16 mmHg. In the 25 successful eyes, mean IOP was 27.7±9.5 mmHg (range 13–48) preoperatively and 12.0±3.0 mmHg (range 7–18) (p<0.0001) at the end of the follow-up period. Mean VA ranged from 0.35±0.34 to 0.32±0.32 (n.s.). Intraoperative complications included Descemet rupture (7), with iris plugging in two cases; choroidal deroofing (3), irregular incision of Schlemm's canal (2). Postoperative complications included: self-resolving 2-mm hyphema (4); IOP spike (1); inadvertent filtering bleb (2); hypotony with choroidal detachment for one week (1). Conclusions In this short-term study, viscocanalostomy proved effective and safe in lowering IOP in glaucomatous eyes.

Hemorrhagic Descemet’s Membrane Detachment in Non-penetrating Glaucoma Surgery

2020 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Shirin Djavanmardi ◽  
Carlos A. Arciniegas-Perasso ◽  
Susana Duch ◽  
Elena Avila ◽  
Elena Milla
Keyword(s):  
Glaucoma Surgery ◽  
Descemet’S Membrane Detachment ◽  
Descemet's Membrane ◽  
Descemet’S Membrane

Differential P1-purinergic modulation of human Schlemm's canal inner-wall cells

2005 ◽  
Vol 288 (4) ◽  
pp. C784-C794 ◽  
Author(s):  
Mike O. Karl ◽  
Johannes C. Fleischhauer ◽  
W. Daniel Stamer ◽  
Kim Peterson-Yantorno ◽  
Claire H. Mitchell ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Aqueous Humor ◽  
Adenosine Receptors ◽  
Outer Wall ◽  
Outflow Resistance ◽  
Schlemm’S Canal ◽  
Adenosine Receptor Agonists ◽  
Schlemm's Canal ◽  
Aqueous Humor Flow

Intraocular pressure is directly dependent on aqueous humor flow into, and resistance to flow out of, the eye. Adenosine has complex effects on intraocular pressure. Stimulation of A1and A2Aadenosine receptors changes intraocular pressure oppositely, likely through opposing actions on the outflow of aqueous humor. While the cellular sites regulating outflow resistance are unknown, the cells lining the inner wall of Schlemm's canal (SC) are a likely regulatory site. We applied selective adenosine receptor agonists to SC cells in vitro to compare the responses to A1and A2Astimulation. Parallel studies were conducted with human inner-wall SC cells isolated by a novel enzyme-assisted technique and with cannula-derived mixed inner- and outer-wall SC cells. A1agonists increased whole cell currents of both inner-wall and cannula-derived SC cells. An A2Aagonist reduced currents most consistently in specifically inner-wall SC cells. Those currents were also increased by A2B, but not consistently affected by A3, stimulation. A1, A2A, and A3agonists all increased SC-cell intracellular Ca2+. The electrophysiological results are consistent with the possibility that inner-wall SC cells may mediate the previously reported modulatory effects of adenosine on outflow resistance. The results are also consistent with the presence of functional A2B, as well as A1, A2A, and A3adenosine receptors in SC cells.

Angle and Nonpenetrating Glaucoma Surgery

2013 ◽  
Author(s):  
Huijuan Wu ◽  
Teresa C. Chen
Keyword(s):  
Endothelial Cells ◽  
Anterior Chamber ◽  
Trabecular Meshwork ◽  
Glaucoma Surgery ◽  
Anterior Chamber Angle ◽  
Schlemm’S Canal ◽  
Schlemm's Canal ◽  
Outflow Pathway ◽  
Aqueous Outflow ◽  
Chamber Angle

The outflow of aqueous via the anterior chamber angle is a constant process. The aqueous is formed by the ciliary processes and then passes through the pupil from the posterior chamber to the anterior chamber (Figure 2.1). About 83%–96% of the aqueous finally exits the eye into the anterior chamber angle via the trabecular meshwork—Schlemm’s canal—venous system (i.e., the conventional or canalicular outflow pathway). The other 5%–15% of aqueous outflow occurs via uveoscleral outflow (i.e., the unconventional or extracanalicular outflow pathway), with aqueous passing through the ciliary muscle and iris, then entering into the supraciliary and suprachoroidal spaces, and then finally exiting the eye through the sclera or along the penetrating nerves and vessels. Glaucoma is usually associated with aqueous outflow problems through a variety of mechanisms. For the developmental glaucomas, the improper development of the outflow structures is the main reason for high eye pressures. In the primary and secondary open-angle glaucomas, the theories to explain the diminished outflow facility are numerous. Possible etiologies are as follows: deposition of foreign material (such as pigment, red blood cells, glycosaminoglycans, extracellular lysosomes, plaque-like material, and proteins) into the trabecular meshwork (TM) and the wall of Schlemm’s canal (SC), loss of trabecular endothelial cells, structural changes of the inner wall of SC, and abnormal phagocytic activity of trabecular endothelial cells. In angle closure glaucoma, the peripheral iris closes the entrance to the TM by the anterior pulling mechanism or the posterior pushing mechanism, resulting in the direct blockage of conventional outflow. The goal of angle and nonpenetrating procedures is to restore aqueous outflow, thereby lowering intraocular pressure (IOP). Angle surgery restores outflow by re-opening the natural channels for aqueous outflow, and nonpenetrating glaucoma surgery creates an artificial external filtration site and partly restores the normal physiologic pathways. In 1936, Otto Barkan was the first to describe a surgical procedure that creates an internal incision into trabecular tissue under direct magnified view of the anterior chamber angle.

Stegmann Canal Expander for canaloplasty: A novel technique

2018 ◽  
Vol 28 (4) ◽  
pp. 472-478 ◽  
Author(s):  
Matthias C Grieshaber
Keyword(s):  
Intraocular Pressure ◽  
Trabecular Meshwork ◽  
Deep Sclerectomy ◽  
Specific Design ◽  
Schlemm’S Canal ◽  
Schlemm's Canal ◽  
Novel Technique ◽  
Dissection Technique ◽  
Aqueous Outflow ◽  
Outflow System

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.

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