Glaucoma Surgical Procedures

Coverage Summary

This policy covers clinical review criteria for glaucoma surgical procedures including canaloplasty, microinvasive glaucoma surgery (MIGS) devices such as the iStent and Hydrus, the XEN Gel Implant, and the Cypass device. The policy stance is mixed: canaloplasty, iStent/Hydrus (when criteria are met and performed with cataract surgery), and XEN are addressed with specific medical necessity criteria and coding; Cypass is listed as not medically necessary following market withdrawal. The document distinguishes Medicare versus non‑Medicare members (with separate notes on review requirements) and describes the high‑level intent that coverage is governed by the listed medical necessity criteria and applicable CPT/HCPCS coding and documentation requirements.

Key thresholds, codes, and scope summary

MIGS (iStent/Hydrus) IOP threshold> 21 mmHg (unless a lower target IOP is clinically justified and documented)

Unmedicated IOP exclusion for iStent/Hydrus> 36 mmHg after medication washout (excludes candidacy)

Refractory glaucoma definition for XEN GelMean diurnal medicated IOP ≥20 mm Hg on maximally tolerated medical therapy (≥4 classes) or fewer if tolerability/efficacy issues

Canaloplasty CPT codes66174 (without retention of device/stent), 66175 (with retention of device/stent)

XEN Gel / aqueous drainage device codes0449T, 66183 (considered medically necessary when criteria met)

iStent/Hydrus CPT when combined with cataract surgery66989, 66991 (coverage requires concomitant cataract surgery and listed criteria)

Scope summaryClinical review criteria governing medical necessity coverage for canaloplasty and microinvasive glaucoma surgery (iStent, Hydrus, XEN, Cypass) with separate Medicare/non‑Medicare notes; Cypass removed from coverage; documentation and coding requirements specified

Medical Necessity Criteria

XEN Gel Implant (0449T, 66183)

Xen Gel Implant will be considered medically necessary when ONE of the following are met:

ANY of the following

Refractory glaucoma, defined as progressive damage and mean diurnal medicated IOP ≥20 mm Hg on maximally tolerated medical therapy (i.e., ≥4 classes of topical IOP-lowering medications, or fewer in the case of tolerability or efficacy issues)≥20 mmHg
Previous surgical treatment has failed (angle-based procedures, laser trabeculoplasty)
Primary open-angle glaucoma

Contraindications and Device-specific Status

iStent/Hydrus Contraindications / Exclusions (general MIGS exclusions)

Contraindicated in the following patients:

ANY of the following

Eyes with angle-closure glaucoma
Eyes with traumatic, malignant, uveitic, or neovascular glaucoma or discernible congenital anomalies of the anterior chamber (AC) angle
Patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other condition that may cause elevated episcleral venous pressure

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Provider Actions & Documentation Requirements

Prior Authorization

Medical necessity review for Non-Medicare canaloplasty

Canaloplasty for non-Medicare members requires a medical necessity review and must meet the policy criteria for coverage. Verify plan-specific pre-authorization requirements using the Pre-authorization Code Check.

66174
66175

Documentation Required

Supporting clinical documentation for surgery requests

Submit the last 6 months of clinical notes from the requesting provider and/or specialist to support medical necessity for surgical requests.

Specialist consultation notes

Coding

Cypass (no longer available) - Not Medically NecessaryHCPCSNot Covered

0474T

Insertion of anterior segment aqueous drainage device, with creation of intraocular reservoir, internal approach, into the supraciliary space

Background & Evidence Summary

Glaucoma is an optic neuropathy caused by elevated intraocular pressure (IOP) leading to progressive visual field loss; treatment aims to lower IOP to prevent or slow vision loss using topical medications, laser trabeculoplasty, and incisional surgeries such as trabeculectomy.

Trabeculectomy creates a conjunctival bleb to drain aqueous humor and can effectively lower IOP but carries risks (hypotony, bleb leaks, infection, cataract progression, scarring) that have motivated development of less invasive alternatives.

Canaloplasty is a nonpenetrating procedure that restores trabeculocanalicular outflow by 360° viscodilation and placement of a tensioning suture in Schlemm's canal using a microcatheter; it avoids creating a bleb and may be suitable for patients who cannot or should not have bleb‑forming surgery, but it has a steep learning curve and specific contraindications.

MIGS describes ab interno, minimally traumatic procedures often performed with cataract surgery to reduce IOP and medication burden. FDA‑cleared devices include the iStent (trabecular bypass), CyPass (supraciliary—now withdrawn), and XEN (subconjunctival gelatin stent). These devices differ in mechanism, indications, and safety profiles.

The Kaiser MTAC evidence reviews concluded that canaloplasty lacked sufficient comparative evidence versus medical therapy or trabeculectomy to meet MTAC criteria, and the XEN Gel Implant similarly did not meet MTAC criteria due to absence of randomized trial evidence and reliance on low‑quality observational studies with variable success rates and frequent need for additional surgeries.

Evidence Item	Summary/Policy Implication
Canaloplasty MTAC conclusion (2008/2009)	MTAC found insufficient evidence from comparative trials to determine superiority or equivalence to medical therapy or trabeculectomy; concluded canaloplasty does not meet Kaiser Permanente MTAC criteria (use not meeting MTAC). Policy therefore requires documented criteria for canaloplasty and does not consider canaloplasty to meet MTAC evidence standards.
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Medicare Determinations

Medicare‑specific determinations referenced in the policy include the Local Coverage Determination Micro‑Invasive Glaucoma Surgery (MIGS) (L38299) and the Local Coverage Article Billing and Coding: Micro‑Invasive Glaucoma Surgery (MIGS) (A57863); no CMS National Coverage Determination (NCD) is specified.

The policy notes applicable CPT codes for canaloplasty (66174, 66175) and states that for non‑Medicare members canaloplasty requires meeting the listed medical necessity criteria, while for Medicare members the document indicates 'Medical Necessity Review not required' for canaloplasty (verify via the Medicare coverage article links).

The policy also lists coding and documentation requirements for iStent/Hydrus and XEN (e.g., 0449T, 66183, 66989, 66991) and directs submission of clinical notes to support medical necessity.

Definitions

Refractory glaucoma (policy): Progressive damage and mean diurnal medicated IOP ≥20 mm Hg on maximally tolerated medical therapy (≥4 classes of topical IOP‑lowering medications, or fewer if tolerability/efficacy issues).

MIGS: Micro‑invasive or minimally invasive glaucoma surgery — ab interno procedures with minimal trauma, often performed concomitantly with cataract surgery to reduce intraocular pressure and medication burden.

Revision History

2018-08-29device removal / coverage change

Manufacturer withdrew the Cypass device from the market for safety concerns; Cypass is no longer covered (code 0474T).

2018-11-14coverage criteria / coding addition

Language and coding for iStent (and Hydrus) were added; codes 66989 and 66991 included for iStent/Hydrus when criteria met (used with cataract surgery).

2019-07-08MTAC review / policy conclusion

MTAC concluded XEN Gel Implant (XEN) does not meet Kaiser Permanente MTAC criteria due to lack of high-quality randomized evidence and variable success rates; policy documents MTAC findings and coverage decisions for XEN.