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Update on Schlemm's canal based procedures.

Mansouri K, Shaarawy T - Middle East Afr J Ophthalmol (2015 Jan-Mar)

Bottom Line: IOP was lowered 44% at 24 months while maintaining a favorable safety profile.A prerequisite for functionality of these techniques is the integrity of the distal outflow system.At present, however, it is not possible to conclude whether these novel procedures will be viable alternatives to standard filtering surgery over the long-term.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland, Colorado, USA ; Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.

ABSTRACT
Surgical options for glaucoma have expanded in recent years. This article provides an evidence-based update on the novel or emerging surgical techniques for the treatment of open-angle glaucoma that are based on the Schlemm's canal (SC). Canaloplasty is an ab externo approach and was developed as an alternative to traditional filtering surgeries. The Hydrus microstent (Ivantis Inc., Irvine, CA) is a so-called SC scaffold that directly bypasses the trabecular meshwork to drain aqueous humor into the SC, which it keeps dilated over approximately one quadrant. Canaloplasty has also been shown to lower intraocular pressure (IOP) by up to 40% and combined with cataract surgery. IOP was lowered 44% at 24 months while maintaining a favorable safety profile. The Hydrus device has been proposed as an adjunct to cataract extraction surgery. To date, no published evidence from clinical trials is available on its in vivo safety and efficacy. Schlemm's canal based glaucoma procedures show promise as alternative treatments to traditional glaucoma surgery. Surgeons must be comfortable with angle anatomy. A prerequisite for functionality of these techniques is the integrity of the distal outflow system. At present, however, it is not possible to conclude whether these novel procedures will be viable alternatives to standard filtering surgery over the long-term.

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(a) Canaloplasty. Circumferential dilation of Schlemm's canal with the microcatheter; (b) note the blinking light of the Cather's tip (a)
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Figure 1: (a) Canaloplasty. Circumferential dilation of Schlemm's canal with the microcatheter; (b) note the blinking light of the Cather's tip (a)

Mentions: The beacon tip of the microcatheter (iTrack) is illuminated using a laser-diode based micro illumination system ( i Lumin, iScience International, Menlo Park, California, USA). The catheter is 250 mm in diameter at the tip with a shaft diameter of 200 mm [Figure 1a and b]. Its lumen allows the injection of an ocular viscoelastic device (OVD) to inflate the canal. The device also contains an optical fiber with a lighted beacon at the tip to indicate the course of the catheter. The microcatheter is then cannulated 360° through SC until it exits from the other ostium. A 10-0 prolene suture is tied to its distal end, and the microcatheter is withdrawn into the canal in the opposite direction from which it was introduced, thereby threading the suture through SC. This step should be performed in a smooth continuous movement. As the tip and suture are retracted, OVD is injected every two clock hours through a one-eighth turn of the inbuilt viscoelastic injector. The suture in the canal is tightened, causing distention of the TM inwards and a further distention of the canal. This can be verified intraoperatively using the custom-built high-resolution ultrasound system (iUltrasound, iScience International, Menlo Park, California, USA). After satisfactory suture tightening, the deep scleral flap is excised creating a “scleral lake,” and the ends of the suture are tied with enough tension to distend the TM inside the eye. The superficial flap is then closed tightly.


Update on Schlemm's canal based procedures.

Mansouri K, Shaarawy T - Middle East Afr J Ophthalmol (2015 Jan-Mar)

(a) Canaloplasty. Circumferential dilation of Schlemm's canal with the microcatheter; (b) note the blinking light of the Cather's tip (a)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4302475&req=5

Figure 1: (a) Canaloplasty. Circumferential dilation of Schlemm's canal with the microcatheter; (b) note the blinking light of the Cather's tip (a)
Mentions: The beacon tip of the microcatheter (iTrack) is illuminated using a laser-diode based micro illumination system ( i Lumin, iScience International, Menlo Park, California, USA). The catheter is 250 mm in diameter at the tip with a shaft diameter of 200 mm [Figure 1a and b]. Its lumen allows the injection of an ocular viscoelastic device (OVD) to inflate the canal. The device also contains an optical fiber with a lighted beacon at the tip to indicate the course of the catheter. The microcatheter is then cannulated 360° through SC until it exits from the other ostium. A 10-0 prolene suture is tied to its distal end, and the microcatheter is withdrawn into the canal in the opposite direction from which it was introduced, thereby threading the suture through SC. This step should be performed in a smooth continuous movement. As the tip and suture are retracted, OVD is injected every two clock hours through a one-eighth turn of the inbuilt viscoelastic injector. The suture in the canal is tightened, causing distention of the TM inwards and a further distention of the canal. This can be verified intraoperatively using the custom-built high-resolution ultrasound system (iUltrasound, iScience International, Menlo Park, California, USA). After satisfactory suture tightening, the deep scleral flap is excised creating a “scleral lake,” and the ends of the suture are tied with enough tension to distend the TM inside the eye. The superficial flap is then closed tightly.

Bottom Line: IOP was lowered 44% at 24 months while maintaining a favorable safety profile.A prerequisite for functionality of these techniques is the integrity of the distal outflow system.At present, however, it is not possible to conclude whether these novel procedures will be viable alternatives to standard filtering surgery over the long-term.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland, Colorado, USA ; Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.

ABSTRACT
Surgical options for glaucoma have expanded in recent years. This article provides an evidence-based update on the novel or emerging surgical techniques for the treatment of open-angle glaucoma that are based on the Schlemm's canal (SC). Canaloplasty is an ab externo approach and was developed as an alternative to traditional filtering surgeries. The Hydrus microstent (Ivantis Inc., Irvine, CA) is a so-called SC scaffold that directly bypasses the trabecular meshwork to drain aqueous humor into the SC, which it keeps dilated over approximately one quadrant. Canaloplasty has also been shown to lower intraocular pressure (IOP) by up to 40% and combined with cataract surgery. IOP was lowered 44% at 24 months while maintaining a favorable safety profile. The Hydrus device has been proposed as an adjunct to cataract extraction surgery. To date, no published evidence from clinical trials is available on its in vivo safety and efficacy. Schlemm's canal based glaucoma procedures show promise as alternative treatments to traditional glaucoma surgery. Surgeons must be comfortable with angle anatomy. A prerequisite for functionality of these techniques is the integrity of the distal outflow system. At present, however, it is not possible to conclude whether these novel procedures will be viable alternatives to standard filtering surgery over the long-term.

Show MeSH
Related in: MedlinePlus