Medicare Reimbursement for iStent Trabecular Micro-Bypass Stent (Glaukos)



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Q What is an iStent® Trabecular Micro-Bypass aqueous drainage device?

A  It is an implantable device to divert aqueous humor from the anterior chamber to Schlemm’s canal. The iStent  inject® W creates two patent bypass pathways through the trabecular meshwork – the main source of resistance for  aqueous outflow – resulting in multi-directional flow through Schlemm’s canal. The stents are placed two to three clock  hours apart to deliver access to multiple collector channels.


Q  What are the indications for implanting an iStent?

A  As approved by the FDA in 2012, the iStent “…is indicated for use in conjunction with cataract surgery for the  reduction of intraocular pressure (IOP) in adult patients with mild or moderate open-angle glaucoma currently treated  with ocular hypotensive medication.”1 The iStent inject W was FDA-approved in 2018, for similar indications.2


Q  Do Medicare and other payers cover implantation of the iStent aqueous drainage device?

A  Yes, all Medicare Administrative Contractors (MACs) and most other payers cover these procedures when performed in accordance with FDA-approved directions for use, in conjunction with medically necessary cataract surgery.


Q  Is there reimbursement for stand-alone iStent implantation without cataract surgery?

A  Not at present because the procedure is still in clinical trials, not FDA approved, and is experimental and  investigational.


Q  What CPT code describes implantation of the iStent aqueous drainage device?

A  In 2022, there are 3 new codes for these procedures: 66991, 66989, and 0671T; the prior codes, 0191T and +0376T,  were deleted.

66991 – Extracapsular cataract removal with insertion of intraocular lens prosthesis (1-stage procedure), manual or  mechanical technique (eg, irrigation and aspiration or phacoemulsification); with insertion of intraocular (eg,  trabecular meshwork, supraciliary, suprachoroidal) anterior segment aqueous drainage device, without extraocular  reservoir, internal approach, one or more.

66989 –Extracapsular cataract removal with insertion of intraocular lens prosthesis (1-stage procedure), manual or  mechanical technique (eg, irrigation and aspiration or phacoemulsification), complex, requiring devices or techniques  not generally used in routine cataract surgery (eg, iris expansion device, suture support for intraocular lens, or primary  posterior capsulorrhexis) or performed on patients in the amblyogenic developmental stage; with insertion of  intraocular (eg, trabecular meshwork, supraciliary, suprachoroidal) anterior segment aqueous drainage device, without  extraocular reservoir, internal approach, one or more. Additionally, for the experimental, stand-alone  procedure, use 0671T (Insertion of anterior segment aqueous drainage device into the trabecular meshwork, without  external reservoir, and without concomitant cataract removal, one or more).


Q  What does Medicare allow for the surgeon for these procedures?

A  The 2022 national Medicare Physician Fee Schedules (MPFS) allowed amount for 66991 is $683, and $857 for  66989. There is no defined allowed amount in the MPFS for 0671T.3


Q  What does Medicare allow for the facility for these procedures, including the prosthetic device?

A  The 2022 ambulatory surgery center (ASC) allowed amount for 66989 and 66991 is $3,246. For a hospital  outpatient department (HOPD), it is $4,251. For 0671T, the allowed amounts are $1,601 and $2,121 respectively  although there are no claims paid at this time.4


Q  Is there separate Part B Medicare reimbursement for the iStent aqueous drainage device?

A  No. Part B Medicare payment for the device is included in the facility reimbursement for APC 1526. On a UB-04  claim, use HCPCS code C1783 with revenue code 278 to identify the ADD.5 Do not report a HCPCS code for the device  on a CMS-1500 claim. For other third-party payers, check their instructions and your contract.


Q  May gonioscopy (92020) be billed with the claim for the surgery?

A  No. Gonioscopy is required during surgery to implant the device and is an incidental part of the service. CPT  instructs that a code designated as a “separate procedure”, such as gonioscopy, should not be reported in addition to  the code for the total procedure of which it is considered an integral component.


Q  Are there any NCCI edits or bundles for CPT 0191T?

A  Yes; NCCI edits include paracentesis and anterior chamber injections, as well as others. In addition, all edits in place for the concurrent cataract procedure pertain. Check NCCI edits periodically as they change quarterly. Most third party payers follow NCCI edits, but not all; check your payer contracts.


Q  What is the global period for 66989 and 66991?

A  In the Medicare Physician Fee Schedule, the global period for 66989 and 66991 surgery is 90 days.


Q  Can a surgeon co-manage postop care for 66989 and 66991?

A  Yes, Medicare’s rules for splitting postoperative care during the 90 day global period between the surgeon and  another physician apply. The CMS regulations and the professional society guidance on this issue are especially  meaningful and relevant for a combined cataract and MIGS procedure.6,7,8



1 iStent directions for use.
2 approval, and iStent inject directions for use
3 CMS 2022 MPFS
4 CMS 2022 OPPS Payment by HCPCS Code
5 CMS requires HOPDs to report C1783 (Ocular implant, aqueous drainage assist device) on Medicare claims for  tracking purposes.
6 CMS. Global Surgery Booklet.
7 ASCRS. Ophthalmic Postoperative Care.
8 AAO. Comprehensive Guidelines for the Co-Management of Ophthalmic Postoperative Care.



Provided Courtesy of Glaukos Corporation  (800) 452-8567


Last updated January 1, 2022


The reimbursement information is provided by Corcoran Consulting Group based on publicly available information from CMS, the AMA, etc. The reader is strongly encouraged to review federal and state laws, regulations, code sets, and official instructions  promulgated by Medicare and other payers. This document is not an official source nor is it a complete guide on reimbursement. Although we believe this information is accurate at the time of publication, the reader is reminded that this information, including references and hyperlinks, changes over time, and may be incorrect at any time following publication.

© 2022 Corcoran Consulting Group.   All rights reserved. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a retrieval system, without the written permission of the publisher. CPT is a registered trademark of the American Medical Association.

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