Latest Review Date: April 2024

Category: Vision                                                               

POLICY:

Viscocanalostomy is considered investigational.

Canaloplasty may be considered medically necessary as a method to reduce intraocular pressure in individuals with chronic primary open-angle glaucoma under the following conditions:

• Medical therapy has failed to adequately control intraocular pressure, AND
• The individual is not a candidate for any other intraocular pressure lowering procedure (e.g. trabeculectomy or glaucoma drainage implant) due to a high risk for complications.

Canaloplasty is considered investigational under all other conditions, including angle-closure glaucoma.

Trabeculectomy surgery using ab interno (i.e. Trabectome™) is considered investigational.

DESCRIPTION OF PROCEDURE OR SERVICE:

Glaucoma surgery is intended to reduce intraocular pressure when the target intraocular pressure cannot be reached with medications. Due to complications with established surgical approaches (e.g., trabeculectomy), alternative surgical treatments (e.g., transluminal dilation by viscocanalostomy or canaloplasty) are being evaluated for individuals with glaucoma.

Glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide and is characterized by elevated intraocular pressure (IOP). In 2020, glaucoma affected approximately 52.7 million individuals globally, with a projected increase to 79.8 million in 2040. Glaucoma has been reported to be 7 times more likely to cause blindness and 15 times more likely to cause visual impairment in Black individuals as compared to White individuals. In the U.S. in 2010, Black individuals had the highest prevalence rate of primary open angle glaucoma at 3.4% compared to 1.7% among White individuals.

In the primary (conventional) outflow pathway from the eye, aqueous humor passes through the trabecular meshwork, enters a space lined with endothelial cells (Schlemm canal), drains into collector channels, and then into the aqueous veins. Increases in resistance in the trabecular meshwork and/or the inner wall of the Schlemm canal can disrupt the balance of aqueous humor inflow and outflow, resulting in an increase in IOP and glaucoma risk.

Impaired Aqueous Humor Drainage

In the primary (conventional) outflow pathway from the eye, aqueous humor passes through the trabecular meshwork, enters a space lined with endothelial cells (Schlemm canal), drains into collector channels, and then into the aqueous veins. Increases in resistance in the trabecular meshwork and/or the inner wall of Schlemm canal can disrupt the balance of aqueous humor inflow and outflow, resulting in an increase in intraocular pressure and glaucoma risk.

Treatment

Surgical intervention may be indicated in patients with glaucoma when the target intraocular pressure cannot be reached pharmacologically. Trabeculectomy (guarded filtration surgery) is the most established surgical procedure for glaucoma, allowing aqueous humor to directly enter the subconjunctival space. This procedure creates a subconjunctival reservoir with a filtering “bleb” on the eye, which can effectively reduce intraocular pressure, but is associated with numerous and sometimes sight-threatening complications (e.g., leaks, hypotony, choroidal effusions and hemorrhages, hyphemas or bleb-related endophthalmitis) and long-term failure. Other surgical procedures (not addressed herein) include trabecular laser ablation and deep sclerectomy, which removes the outer wall of Schlemm canal and excises deep sclera and peripheral cornea.

More recently, the Trabectome™, an electrocautery device with irrigation and aspiration, has been used to selectively ablate the trabecular meshwork and inner wall of Schlemm canal without external access or creation of a subconjunctival bleb. Intraocular pressure with this ab interno procedure is typically higher than the pressure achieved with standard filtering trabeculectomy. Aqueous shunts may also be placed to facilitate drainage of aqueous humor (discussed in another policy). Complications from anterior chamber shunts include corneal endothelial failure and erosion of the overlying conjunctiva.

Alternative nonpenetrating methods being evaluated to treat glaucoma are viscocanalostomy and canaloplasty. Viscocanalostomy is a variant of deep sclerectomy and unroofs and dilates the Schlemm canal without penetrating the trabecular meshwork or anterior chamber. A high-viscosity viscoelastic solution (e.g., sodium hyaluronate) is used to open the canal and create a passage from the canal to a scleral reservoir. It has been proposed that viscocanalostomy may lower intraocular pressure while avoiding bleb-related complications.

Canaloplasty, which evolved from viscocanalostomy, involves dilation and tension of the Schlemm canal with a suture loop between the inner wall of the canal and the trabecular meshwork. This procedure uses the iTrack™ illuminated microcatheter to access and dilate the length of the Schlemm canal and to pass the suture loop through the canal. An important difference between viscocanalostomy and canaloplasty is that canaloplasty attempts to open the entire length of the Schlemm canal, rather than one section.

Because aqueous humor outflow is pressure-dependent, the pressure in the reservoir and venous system is critical for reaching the target intraocular pressure. Therefore, some procedures may not reduce intraocular pressure below the pressure of the distal outflow system used (e.g., <15 mm Hg), and are not indicated for patients for whom very low intraocular pressure is desired (e.g., those with advanced glaucoma).

KEY POINTS:

The most recent literature review was updated through January 22, 2024.

Summary of Evidence

For individuals who have open-angle glaucoma who have failed medical therapy who receive viscocanalostomy, the evidence includes small randomized controlled trials (RCTs) comparing viscocanalostomy with trabeculectomy. Relevant outcomes are symptoms, morbid events, quality of life, and medication use. Meta-analysis of these trials has indicated that trabeculectomy has a greater intraocular pressure lowering effect than viscocanalostomy. Reduction in intraocular pressure was greater with canaloplasty than viscocanalostomy in a small within-subject comparison. Viscocanalostomy has not been shown to be as good as or better than established alternatives. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

For individuals who have open-angle glaucoma who have failed medical therapy who receive canaloplasty, the evidence includes two RCTs, a comparative effectiveness review, and several case series. Relevant outcomes are symptoms, morbid events, quality of life, and medication use. The RCTs found a significantly higher complete success rates with trabeculectomy than with canaloplasty in one trial and a significantly lower mean intraocular pressure in another trial. However, higher complication rates were also observed with trabeculectomy. A non-randomized study found both canaloplasty and iStent bypass implantation, when combined with phacoemulsion, had similar 1-year post-surgery intraocular pressure and glaucoma medication reductions, but canaloplasty resulted in more early postoperative complications. A systematic review found that canaloplasty provided modest intraocular pressure reduction (to ~16 mm Hg) with minor intraoperative or postoperative complications. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Practice Guidelines and Position Statements

American Academy of Ophthalmology

A technology assessment from the American Academy of Ophthalmology (2011) included canaloplasty in its review of novel glaucoma procedures. The Academy concluded that all the techniques and devices reviewed were still in the initial stage (≤ 5 years) of clinical experience and lacked widespread use, with only Level III evidence (cohort studies) supporting the procedures. In addition to describing potential advantages and disadvantages of the procedure, it was noted that the long-term effects of a foreign body in the Schlemm canal are not known.

National Institute for Health and Clinical Excellence

In 2017, the National Institute for Health and Care Excellence (NICE) updated its 2008 guidance on ab externo canaloplasty for primary open-angle glaucoma. The current recommendation is that the “…evidence on the safety and efficacy of ab externo canaloplasty for primary open-angle glaucoma is adequate to support the use of this procedure provided that standard arrangements are in place for clinical governance, consent and audit”.

Similarly, in 2017 (amended in 2022), NICE updated its 2009 guidance on the diagnosis and management of chronic open-angle glaucoma. When comparing penetrating surgery (trabeculectomy) with nonpenetrating surgery (deep sclerectomy and viscocanalostomy), NICE found moderate-quality evidence that trabeculectomy is more effective than nonpenetrating surgery in reducing the number of eyes with an unacceptable intraocular pressure (IOP), but was more likely to cause cataract formation and persistent hypotony at 12- to 36-month follow-up. There was very low quality evidence that trabeculectomy is more effective than nonpenetrating surgery in reducing IOP from baseline to six- and 12-month follow-up, but the effect size might have been too small to be clinically significant. The guidance recommended offering information on the risks and benefits associated with surgery and offering surgery (type not specified) with pharmacologic augmentation to people with chronic open-angle glaucoma at risk of progressing to sight loss, despite treatment (recommendation 1.4.21).

In 2022, NICE published an interventional procedures guidance on ab interno canaloplasty for open-angle glaucoma.The current recommendation states that "evidence on the safety of ab interno canaloplasty for open-angle glaucoma shows no major safety concerns. Evidence on the efficacy is limited in quality and quantity, particularly in the long term. Therefore, this procedure should only be used with special arrangements for clinical governance, consent, and audit or research."

U.S. Preventive Services Task Force Recommendations

Not applicable.

KEY WORDS:

iTrack™, Viscocanalostomy, Canaloplasty, surgical ophthalmic microcannula, Trabectome, Trabeculectomy, Viscocanalostomy, ab interno, Trabeculotomy

APPROVED BY GOVERNING BODIES:

In 2004, the iTrack™ (iScience Interventional) was cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process as a surgical ophthalmic microcannula that is indicated for the general purpose of “fluid infusion and aspiration, as well as illumination, during surgery.” In 2008, the iTrack™ received FDA clearance for “catheterization and viscodilation of Schlemm canal to reduce intraocular pressure in adult patients with open angle glaucoma.” FDA product code: MPA.

In 2017, the OMNI® Surgical System (Sight Sciences, Inc.) was cleared for marketing by the FDA through the 510(k) process as a manually operated device for the delivery of small amounts of viscoelastic fluid during ophthalmic surgery. It is also indicated to cut trabecular meshwork tissue during trabeculotomy procedures (K173332). In 2020, the OMNI® Plus Surgical System was cleared for the same indications for use as the predicate OMNI system (K201953). In 2021, the OMNI® Surgical System was cleared for marketing by the FDA through the 510(k) process for canaloplasty (microcatheterization and transluminal viscodilation of Schlemm's canal) followed by trabeculotomy (cutting of trabecular meshwork) to reduce intraocular pressure in adult patients with primary open-angle glaucoma (K202678). FDA product code: MRH.

BENEFIT APPLICATION:

Coverage is subject to member’s specific benefits. Group-specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply.

FEP:  Special benefit consideration may apply.  Refer to member’s benefit plan. 

CURRENT CODING:

CPT Codes:

REFERENCES:

1. Allison K, Patel DG, Greene L. Racial and Ethnic Disparities in Primary Open-Angle Glaucoma Clinical Trials: A Systematic Review and Meta-analysis. JAMA Netw Open. May 03 2021; 4(5): e218348.
2. Ayyala RS, Chaudhry AL, Okogbaa CB, et al. Comparison of surgical outcomes between canaloplasty and trabeculectomy at 12 months' follow-up. Ophthalmology. Dec 2011; 118(12): 2427-33.
3. Brusini P. Canaloplasty in open-angle glaucoma surgery: a four-year follow-up. ScientificWorldJournal. 2014; 2014: 469609.
4. Bull H, von Wolff K, Körber N, et al. Three-year canaloplasty outcomes for the treatment of open-angle glaucoma: European study results. Graefes Arch Clin Exp Ophthalmol. Oct 2011; 249(10): 1537-45.
5. Chai C, Loon SC. Meta-analysis of viscocanalostomy versus trabeculectomy in uncontrolled glaucoma. J Glaucoma. 2010; 19(8): 519-27.
6. Eldaly MA, Bunce C, Elsheikha OZ, et al. Non-penetrating filtration surgery versus trabeculectomy for open-angle glaucoma. Cochrane Database Syst Rev. Feb 15 2014; (2): CD007059.
7. Francis BA, Singh K, Lin SC, et al. Novel glaucoma procedures: a report by the American Academy of Ophthalmology. Ophthalmology. Jul 2011; 118(7): 1466-80.
8. Gallardo MJ, Dhamdhere K, Dickerson JE. Canaloplasty and Trabeculotomy Ab Interno Combined with Cataract Surgery: 12-Month Outcomes in Hispanic Patients with Open-Angle Glaucoma. Clin Ophthalmol. 2022; 16: 905-908.
9. Gallardo MJ, Pyfer MF, Vold SD, et al. Canaloplasty and Trabeculotomy Combined with Phacoemulsification for Glaucoma: 12-Month Results of the GEMINI Study. Clin Ophthalmol. 2022; 16: 1225-1234.
10. Gallardo MJ. 36-Month Effectiveness of Ab-Interno Canaloplasty Standalone versus Combined with Cataract Surgery for the Treatment of Open-Angle Glaucoma. Ophthalmol Glaucoma. 2022; 5(5): 476-482.
11. Gilmour DF, Manners TD, Devonport H, et al. Viscocanalostomy versus trabeculectomy for primary open angle glaucoma: 4-year prospective randomized clinical trial. Eye (Lond). Sep 2009; 23(9): 1802-7.
12. Gołaszewska K, Obuchowska I, Konopińska J. First-Generation iStent Bypass Implantation versus ab ExternoCanaloplasty Combined with Phacoemulsification in Patients with Primary Open Angle Glaucoma-12-Month Follow-Up. JClin Med. Sep 01 2023; 12(17).
13. Greenwood MD, Yadgarov A, Flowers BE, et al. 36-Month Outcomes from the Prospective GEMINI Study: Canaloplastyand Trabeculotomy Combined with Cataract Surgery for Patients with Primary Open-Angle Glaucoma. Clin Ophthalmol.2023; 17: 3817-3824.
14. Grieshaber MC, Peckar C, Pienaar A, et al. Long-term results of up to 12 years of over 700 cases of viscocanalostomy for open-angle glaucoma. Acta Ophthalmol. Jun 2015; 93(4): 362-7.
15. Grieshaber MC, Pienaar A, Olivier J, et al. Canaloplasty for primary open-angle glaucoma: long-term outcome. Br J Ophthalmol. Nov 2010; 94(11): 1478-82.
16. IOM (Institute of Medicine). 2011. Clinical Practice Guidelines We Can Trust. Washington, DC: The National Academies Press.
17. Khaimi MA, Koerber N, Ondrejka S, et al. Consistency in Standalone Canaloplasty Outcomes Using the iTrackMicrocatheter. Clin Ophthalmol. 2024; 18: 173-183.
18. Klink T, Sauer J, Körber NJ, et al. Quality of life following glaucoma surgery: canaloplasty versus trabeculectomy. Clin Ophthalmol. 2015; 9: 7-16.
19. Kobayashi H, Kobayashi K, Okinami S. A comparison of the intraocular pressure-lowering effect and safety of viscocanalostomy and trabeculectomy with mitomycin C in bilateral open-angle glaucoma. Graefes Arch Clin Exp Ophthalmol. May 2003; 241(5): 359-66.
20. Koerber N, Ondrejka S. Four-Year Efficacy and Safety of iTrack Ab-interno Canaloplasty as a Standalone Procedure and Combined with Cataract Surgery in Open-Angle Glaucoma. Klin Monbl Augenheilkd. Apr 14 2022.
21. Koerber NJ. Canaloplasty in one eye compared with viscocanalostomy in the contralateral eye in patients with bilateral open-angle glaucoma. J Glaucoma. Feb 2012; 21(2): 129-34.
22. Koerber N, Ondrejka S. 6-Year Efficacy and Safety of iTrack Ab-interno Canaloplasty as a Standalone Procedure andCombined with Cataract Surgery in Primary Open-Angle and Pseudoexfoliative Glaucoma. J Glaucoma. Sep 12 2023.
23. Lewis RA, von Wolff K, Tetz M, et al. Canaloplasty: circumferential viscodilation and tensioning of Schlemm's canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults: interim clinical study analysis. J Cataract Refract Surg. Jul 2007; 33(7): 1217-26.
24. Lewis RA, von Wolff K, Tetz M, et al. Canaloplasty: circumferential viscodilation and tensioning of Schlemm canal using a flexible microcatheter for the treatment of open-angle glaucoma in adults: two-year interim clinical study results. J Cataract Refract Surg. May 2009; 35(5): 814-24.
25. Lewis RA, von Wolff K, Tetz M, et al. Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma. J Cataract Refract Surg. Apr 2011; 37(4): 682-90.
26. Matlach J, Dhillon C, Hain J, et al. Trabeculectomy versus canaloplasty (TVC study) in the treatment of patients with open-angle glaucoma: a prospective randomized clinical trial. Acta Ophthalmol. Dec 2015; 93(8): 753-61.
27. Mosaed S, Dustin L, Minckler DS. Comparative outcomes between newer and older surgeries for glaucoma. Trans Am Ophthalmol Soc. Dec 2009; 107: 127-33.
28. Murphy Iii JT, Terveen DC, Aminlari AE, et al. A Multicenter 12-Month Retrospective Evaluation of Canaloplasty and Trabeculotomy in Patients with Open-Angle Glaucoma: The ROMEO 2 Study. Clin Ophthalmol. 2022; 16: 3043-3052.
29. National Institute for Health and Care Evidence (NICE). Ab externo canaloplasty for primary open-angle glaucoma [IPG591]. 2017; www.nice.org.uk/guidance/ipg591.
30. National Institute for Health and Care Evidence (NICE). Canaloplasty for primary open-angle glaucoma [IPG260]. 2008; www.nice.org.uk/guidance/ipg260.
31. National Institute for Health and Care Excellence (NICE). Glaucoma: diagnosis and management [NG81]. 2022; www.nice.org.uk/guidance/NG81.
32. National Institute for Health and Care Excellence (NICE). Ab interno canaloplasty for open-angle glaucoma [IPG745]. 2022; www.nice.org.uk/guidance/ipg745.
33. National Institute for Health and Care Excellence (NICE). Glaucoma: diagnosis and management of chronic open angle glaucoma and ocular hypertension [CG85]. 2009; www.nice.org.uk/guidance/cg85.
34. Ondrejka S, Körber N, Dhamdhere K. Long-term effect of canaloplasty on intraocular pressure and use of intraocular pressure-lowering medications in patients with open-angle glaucoma. J Cataract Refract Surg. Dec 01 2022; 48(12): 1388-1393.
35. Shingleton B, Tetz M, Korber N. Circumferential viscodilation and tensioning of Schlemm canal (canaloplasty) with temporal clear corneal phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: one-year results. J Cataract Refract Surg. Mar 2008; 34(3): 433-40.
36. Stangos AN, Mavropoulos A, Leuenberger PM, et al. The effect of learning curve on the surgical outcome of viscocanalostomy. J Glaucoma. Aug 2012; 21(6): 408-14.
37. Terveen DC, Sarkisian SR, Vold SD, et al. Canaloplasty and trabeculotomy with the OMNI ® surgical system in OAG with prior trabecular microbypass stenting. Int Ophthalmol. Oct 13 2022.
38. Voykov B, Blumenstock G, Leitritz MA, et al. Treatment efficacy and safety of canaloplasty for open-angle glaucoma after 5 years. Clin Exp Ophthalmol. Nov 2015; 43(8): 768-71.
39. Yadgarov A, Dentice K, Aljabi Q. Real-World Outcomes of Canaloplasty and Trabeculotomy Combined with CataractSurgery in Eyes with All Stages of Open-Angle Glaucoma. Clin Ophthalmol. 2023; 17: 2609-2617.
40. Yin P, Li J, Shi Y, et al. Ab interno canaloplasty versus gonioscopy-assisted transluminal trabeculotomy in open-angleglaucoma: a randomised controlled trial. Br J Ophthalmol. Jun 13 2023.

POLICY HISTORY:

Medical Policy Panel, July 2008

Medical Policy Group, September 2008 (1)

Medical Policy Administration Committee, September 2008

Medical Policy Panel, September 2011

Medical Policy Group, August 2012 (2):  Policy re-written to address viscocanalostomy and canaloplasty.  Separated from Aqueous Shunts for Glaucoma policy

Medical Policy Administration Committee, August 2012

Medical Policy Group, October 2012 (2): 2012 Updates to Key Points and References

Medical Policy Panel, August 2013

Medical Policy Group, September 2013 (2): Updated with literature review; no change to policy statement

Medical Policy Panel, August 2014

Medical Policy Group, August 2014 (1): Update to Key Points and References; no change to policy statement

Medical Policy Panel, August 2015

Medical Policy Group, August 2015 (6):  Updates to Key Points and References; no change to policy statement

Medical Policy Panel, March 2016

Medical Policy Group, March 2016 (6):  Updates to Key Points and References; no change to policy statement.

Medical Policy Panel, March 2017

Medical Policy Group, March 2017 (6):  Updates to Key Points; no change to policy statement.

Medical Policy Group, October 2017 (6): Update to policy statement: “Trabeculectomy surgery using ab interno (i.e. Trabectome™) is not medically necessary and is considered investigational.” updated Key Words.

Medical Policy Panel, March 2018

Medical Policy Group, March 2018 (6): Updates to Key Points, Practice Guidelines and References.

Medical Policy Panel, March 2019

Medical Policy Group, April 2019 (6): Updates to Key Points; no change to policy statement.

Medical Policy Panel, March 2020

Medical Policy Group, March 2020 (6): Updates to Key Points.

Medical Policy Panel, March 2021

Medical Policy Group, March 2021 (9): 2021 Updates to Key Points. Policy statement updated to remove “not medically necessary,” no change to policy intent.

Medical Policy Panel, March 2022

Medical Policy Group, March 2022 (9): 2022 Updates to Description, Key Points, References. The following was removed from the policy statement: “Effective for dates of service prior to October 4, 2017”. No change to policy statement intent.

Medical Policy Panel, March 2023

Medical Policy Group, April 2023 (9): Updates to Description, Key Points, Approved Governing Bodies, Benefit Application and References. No change to policy statement.

Medical Policy Panel, March 2024

Medical Policy Group, April 2024 (9): Updates to Key Points and References. No change to policy statement. 

This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.