✍️ improved aqueous drainage is achieved surgically without penetrating into the AC at the time of initial surgery.
✍️ Controversy continues regarding
☝️ long-term success rate
☝️ the long learning curve associated with these challenging techniques.
✍️ in experienced hands, NPGS with augmentation can achieve similar long-term success to that seen with penetrating glaucoma surgery, but final IOPs are often higher than after augmented trabeculectomy surgery.
✍️ Although NPGS has a lower rate of early hypotony after surgery, serious complications were reported including
☝️ severe hypotony
☝️ endophthalmitis
☝️ suprachoroidal haemorrhage
Non-penetrating glaucoma surgery (NPGS) Deep sclerectomy
✍️ Mechanism
☝️ guarded filtration (such as trabeculectomy) but with the rate of drainage being controlled at the level of the trabecular meshwork and Descemet’s membrane, rather than at the scleral flap.
✍️ Outline
☝️ the formation of conjunctival and superficial scleral flaps
☝️ a deep (90% depth) scleral flap to expose Schlemm’s canal.
☝️ Schlemm’s canal is then deroofed and its endothelium and juxtacanalicular trabecular meshwork peeled o to improve drainage.
☝️ Part of the deep scleral flap is then excised to form the deep sclerectomy space.
☝️ anti fibrotics may be applied and an implant may be inserted.
☝️ the conjunctival flap is then closed.
✍️ Variations
☝️ Anti fibrotics
• in high-risk cases
• anti fibrotic agents are sometimes applied to the deep scleral flap to reduce intrascleral scarring.
• no benefit was demonstrated with 5-FU, but improved IOP control with use of MMC.
☝️ Implants
• inserted into the deep scleral space to maintain the space during healing and effectively form an intrascleral bleb
• Implants may either be absorbable (Aqua flow or SKGel) or non-absorbable (T Flux).
• Implant use is associated with better IOP control than deep sclerectomy alone: 69% vs 39%
☝️Goniopuncture
• Nd-YAG goniopuncture is usually used as a 2ry procedure where sufficient IOP control has not been achieved by the surgical procedure alone
• Effectively converts it to a penetrating procedure.
• Sight-threatening complications, such as hypotony, have been reported after goniopuncture.
✍️ Complications
☝️ Moderate hypotony (with a deep AC) is to be expected and may transiently affect vision.
☝️ high IOP include due to
• inadequate dissection of the trabecular meshwork and Descemet’s membrane (treated with Nd-yAG goni- opuncture)
• rupture of the trabecular meshwork and Descemet’s membrane by mild ocular trauma (rubbing, Valsalva manoeuvre), causing iris prolapse and blockage of the drainage site (requires revision of the drainage site and conversion to a conventional trabeculectomy)
• PAS formation blocking the drainage site (may be reversible with laser iridoplasty).
• Very rarely, detachment of Descemet’s membrane may occur.
☝️ All complications seen with penetrating surgery have been reported with deep sclerectomy.
Non-penetrating glaucoma surgery (NPGS) Viscocanalostomy
✍️ increasing aqueous flow into Schlemm’s canal but there is however little evidence to support this.
✍️ Outline
☝️ similar to deep sclerectomy with the creation of conjunctival, superficial scleral, and deep scleral flaps, and deroofing of Schlemm’s canal.
☝️ Schlemm’s canal is then opened with a viscoelastic, which directly improves drainage by this route.
☝️ the superficial scleral flap is tightly sutured to minimize filtration into the sub-tenon’s space, encouraging drainage into Schlemm’s canal.
☝️ Variations
• Anti fibrotics and implants: as with deep scleretomy
✍️ Complications
☝️ similar to that seen with deep sclerectomy.
☝️ Detachment of Descemet’s membrane (occurring at the time of injection of viscoelastic) occurs more commonly than in deep sclerectomy but is still uncommon.
Non-penetrating glaucoma surgery (NPGS) Micro-invasive glaucoma surgery
✍️ IOP reduction achieved with the use of these surgeries are less than IOP reduction achieved with trabeculectomy.
✍️ their role in the management of advanced disease has not been defined.
✍️ Ex-Press glaucoma filtration device
☝️ small stainless steel minishunt drains aqueous fluid from the AC into the subconjunctival space and is used in conjunction with standard trab- eculectomy surgery.
✍️ Canaloplasty
☝️ performed by passing a 9-0 or 10-0 prolene suture through 360° of Schlemm’s canal with the aid of a microcatheter and viscoelastic to dilate the canal.
☝️ the procedure involves the construction of a deep sclerectomy-type flap to enable Schlemm’s canal to be accessed.
✍️ iStent
☝️ small transtrabecular titanium stent drains aqueous fluid from the AC into Schlemm’s canal. ☝️ placed through a 2.8 mm clear corneal incision with the aid of a gonioscopy lens
☝️ inserted in the inferonasal quadrant of the angle via an introducer.
☝️ Immediate blood reflux from the canal of Schlemm through the stent’s snorkel is a positive sign.
☝️ the iStent can be inserted at the time of phaco cataract surgery or into pseudophakic or phakic eyes.
☝️ the role of the iStent in advanced glaucoma has not yet been defined.
☝️more than one iStent can be tried in the same eye to augment IOP reduction
✍️ Trabectome
☝️ thermal cautery device ablates a 2 to 4 clock-hour segment of trabecular meshwork and Schlemm’s canal under direct visualization with a gonioscopy lens.
☝️ the principle is to connect the AC directly with the collector channels in the canal of Schlemm.
☝️ the trabectome can be used at the time of cataract surgery or in phakic or pseudophakic eyes.
☝️the role of this technology is still being evaluated in advanced glaucoma.
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✍️ CyPass Micro-Stent
☝️ supraciliary microstent is implanted through a 1.5mm clear corneal incision and is designed to increase uveoscleral out flow by draining aqueous from the AC into the suprachoroidal space.
☝️ the device is inserted over a micro-guide wire which creates a small cyclodialysis cleft.
✍️ Solx Gold Shunt
☝️ small Solx Gold Shunt is placed into the supraciliary space through a 3mm incision to increase uveoscleral out flow
☝️ facilitate direct access of aqueous from the AC to the suprachoroidal space.
🛑 All current supraciliary microstents may develop fibrosis around the device, leading to failure.
✍️ The Xen gel stent
☝️ soft, permanent, non-migrating, subconjunctival implant that shunts fluid from the anterior chamber to the subconjunctival space
☝️ compressible and tissue-conforming hydrophilic implant made of porcine gelatin that’s crosslinked with gluteraldehyde,
☝️ cylindrical, 6-mm long implant comes with three different-size lumens: 45 µm; 63 µm; and 140 µm.
☝️ can be used in refractory glaucoma.