Canaloplasty is a non-penetrating surgical technique for glaucoma which aims to restore the natural drainage of fluid from the eye.
Canaloplasty may be performed under local or general anaesthetic. A superficial hinged flap of sclera is made and a deeper flap excised, exposing Schlemm’s canal. A microcatheter with an illuminated tip is introduced into the canal and advanced around its entire circumference. As the catheter tip advances, viscoelastic fluid is injected into the canal to dilate it. After catheterisation of the entire canal length is complete, a suture is tied to the tip of the microcatheter, which is withdrawn, pulling the suture into the canal. The
suture is cut from the microcatheter and tied in a loop encircling the inner wall of the canal. The suture is tightened, so distending the trabecular meshwork with the aim of widening the canal.
The superficial flap is sutured. A special ultrasound imaging system is used to help identify the canal and to visualise the instruments in the canal before, during and after the surgery.
Efficacy
In a case series of 94 patients, successful circumferential catheterisation of Schlemm’s canal was achieved in 88% (83/94) of patients, and a suture was successfully placed in the canal in 79% (74/94) of patients. Mean intraocular
pressure was reduced from 24.7 mmHg at baseline to 15.3 mmHg at 12-month follow-up (p < 0.05). (The normal upper limit for intraocular pressure is 21 mmHg.) The mean number of drugs to lower the intraocular pressure was reduced from 1.9 at baseline to 0.6 at 12-month follow-up.
Furthermore, 88% (50/57) and 96% (46/48) of patients with successful suture placement had intraocular pressures of 21 mmHg or lower after 3 months and 6 months, respectively (with or without drugs to lower intraocular pressure).Four patients had poor intraocular pressure control after canaloplasty and required subsequent trabeculectomy.
The Specialist Advisers considered key efficacy outcomes to include control of intraocular pressure, preservation of the visual field and ocular comfort.
Safety
The case series of 94 patients reported ocular-related complications including hyphema (the presence of blood in the anterior chamber) (3%), elevated intraocular pressure (3%), detachment of Descemet’s membrane (1%), hypotony (abnormally low intraocular pressure) (1%), choroidal effusion (1%) and exposed closure suture (1%) (absolute figures not reported).
In the same case series, the loss of two or more lines of best corrected visual acuity was reported in 25% (18/71) of patients at 1-month follow-up, 7% (5/68) of patients at 3-month follow-up and 9% (4/47) of patients at 12-month follow-up. The authors noted that the decline in visual acuity in these patients was related to disease processes not associated with the canaloplasty procedure.
The Specialist Advisers considered theoretical adverse events to include anterior chamber perforation, tearing of Descemet’s membrane resulting in corneal opacification or retinal damage, intraocular inflammation caused by the suture, cataract formation, sustained increases in intraocular pressure, hypotony, and bleb formation or suture exposure with endophthalmitis.
Showing posts with label Canaloplasty. Show all posts
Showing posts with label Canaloplasty. Show all posts
Friday, August 28, 2009
Thursday, August 27, 2009
Canaloplasty :A new minimally invasive surgery for glaucoma
Glaucoma is the leading cause of blindness in the United States, according to the National Institutes of Health. An estimated 4 million Americans are affected by glaucoma. Glaucoma screenings are suggested for anyone over 40, every two to four years. A routine exam can help identify risk for glaucoma and early signs of the disease. Risk factors for glaucoma include: a family history of the disease, African Americans or Hispanic ancestry, diabetes, certain rare eye diseases and having had an eye injury or having used any corticosteroid preparation for a prolonged period.
Glaucoma is often treated with eye drops that reduce the production of fluid in the eye, or help it drain more quickly. However, when the medicines don't work -- or when patients can't remember to take them once or more daily -- surgery is an option. The traditional surgery is trabeculectomy, in which a portion of the trabecular meshwork is removed, helping to reduce the bottleneck causing elevated eye pressure. Trabeculectomy is considered the gold standard for effectiveness, but can cause infection or other complications serious enough to result in blindness.
Canaloplasty is one of the newest alternatives and involves forcing open a drainage canal, similar to what cardiologists do to unblock clogged arteries. The procedure is sometimes called "angioplasty for the eye." In canaloplasty, an incision is made in the eye and a thin catheter is inserted into Schlemm's Canal, a tube in the trabecular meshwork. Instead of a balloon, a thick clear gel is injected to open the canal. In addition, a suture, or surgical tie, is placed inside the canal and pulled tight to stretch open the trabecular meshwork, says Richard Lewis, a Sacramento, Calif., eye surgeon who serves as a consultant to iScience Interventional Corp., a Menlo Park. Calif., company that sells the catheter.
The procedure takes about a half hour and can be done under local anesthetic, typically in a hospital or outpatient surgery center with a sedative. The cost -- typically $2,500 to $3,500 -- is covered by many insurers, while others decline payment because they say there isn't yet enough evidence for the procedure's effectiveness. Serious complications are rare, but can include swelling, overly low eye pressure and blood in the eye.
Surgeons agree that canaloplasty is a safer option than the traditional surgery, but some urge caution."The results that they've published thus far show great promise," says Douglas Rhee, a glaucoma specialist at the Massachusetts Eye & Ear Infirmary in Boston. "Additional studies need to be done," he adds, including trials that compare it directly to other procedures such as trabeculectomy.
Arthur Sit, assistant professor of ophthalmology at the Mayo Clinic in Rochester, Minn. is concerned that scar tissue left from canaloplasty could make a subsequent trabeculectomy less effective. Dr. Sit prefers trabectome, which he says involves a smaller incision that is less likely to impact later surgeries.
Glaucoma is often treated with eye drops that reduce the production of fluid in the eye, or help it drain more quickly. However, when the medicines don't work -- or when patients can't remember to take them once or more daily -- surgery is an option. The traditional surgery is trabeculectomy, in which a portion of the trabecular meshwork is removed, helping to reduce the bottleneck causing elevated eye pressure. Trabeculectomy is considered the gold standard for effectiveness, but can cause infection or other complications serious enough to result in blindness.
Canaloplasty is one of the newest alternatives and involves forcing open a drainage canal, similar to what cardiologists do to unblock clogged arteries. The procedure is sometimes called "angioplasty for the eye." In canaloplasty, an incision is made in the eye and a thin catheter is inserted into Schlemm's Canal, a tube in the trabecular meshwork. Instead of a balloon, a thick clear gel is injected to open the canal. In addition, a suture, or surgical tie, is placed inside the canal and pulled tight to stretch open the trabecular meshwork, says Richard Lewis, a Sacramento, Calif., eye surgeon who serves as a consultant to iScience Interventional Corp., a Menlo Park. Calif., company that sells the catheter.
The procedure takes about a half hour and can be done under local anesthetic, typically in a hospital or outpatient surgery center with a sedative. The cost -- typically $2,500 to $3,500 -- is covered by many insurers, while others decline payment because they say there isn't yet enough evidence for the procedure's effectiveness. Serious complications are rare, but can include swelling, overly low eye pressure and blood in the eye.
Surgeons agree that canaloplasty is a safer option than the traditional surgery, but some urge caution."The results that they've published thus far show great promise," says Douglas Rhee, a glaucoma specialist at the Massachusetts Eye & Ear Infirmary in Boston. "Additional studies need to be done," he adds, including trials that compare it directly to other procedures such as trabeculectomy.
Arthur Sit, assistant professor of ophthalmology at the Mayo Clinic in Rochester, Minn. is concerned that scar tissue left from canaloplasty could make a subsequent trabeculectomy less effective. Dr. Sit prefers trabectome, which he says involves a smaller incision that is less likely to impact later surgeries.
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