Minimally invasive glaucoma surgeries (MIGS) are becoming more common in the surgical management of glaucoma. A number of procedures are in development, and several currently FDA-approved, including the iStent (Glaukos), CyPass Micro-Stent (Alcon),  Ex-Press Glaucoma Filtration Device (Alcon), Xen Gel Stent (Allergan) and Trabectome (NeoMedix). Each procedure is unique based on the mechanism of action and method of insertion: ab interno and ab externo (Table 1).1 

Just as unique is the coding that accompanies the comanagement of patients undergoing one of these procedures. A clinician’s first task is to remember the difference between an HCPCS level I code and a HCPCS level III code.2,3

Level I

CPT level I codes have several requirements, including:2

• All devices and drugs necessary for performance of the procedure or service have received FDA clearance or approval when such is required for performance of the procedure or service.

• The procedure or service is performed by many physicians or other qualified health care professionals across the United States.

• The procedure or service is performed with frequency consistent with the intended clinical use (i.e., a service for a common condition should have high volume, whereas a service for a rare condition may have low volume).

• The procedure or service is consistent with current medical practice.

• The clinical efficacy of the procedure or service is documented in literature that meets the requirements set forth in the CPT code change application.

As MIGS, such as the iStent procedure here, become more popular, ODs need to be familiar with their role in caring for their glaucoma patients and the coding requirements of postoperative visits. Photo: Constance O. Okeke, MD, MSCE

Level III 

MIGS that have an associated code use CPT category level III codes, which are a set of temporary codes that allow data collection for emerging technology, services, procedures and service paradigms. These codes are used to substantiate widespread usage or to provide documentation for the FDA approval process.3 

Level III codes are not developed as a result of a panel review of an incomplete proposal, the need for more information or a lack of CPT Advisory Committee support of a code change application. Unlike level I codes, CPT level III codes are not referred to the AMA-Specialty RVS Update Committee (RUC) for valuation because no relative value units (RVUs) are assigned to these codes.3 Payment for these services or procedures is based on the policies of payers and not on a yearly fee schedule.

After three to five years of data collection, a committee then decides if the level III code is worthy of becoming a level I code and including all benefits associated with a level I code.

Codes in Action

To be used by a comanaging physician, the CPT code itself must have a global period and have a percentage of the overall CPT reimbursement designated for postoperative care. Comanagement as a formal process is allowed with the only CPT procedure listed for some MIGS, 66183 (insertion of anterior segment aqueous drainage device, without extraocular reservoir, external approach).4 The 2017 CMS National Payment amount is $1047.23, with a 90-day global period and a 10% comanagement percentage.4 Comanaging optometrists would be eligible for $104.72 if they provide postoperative care for the full 90 days. 

As an alternative, clinicians can still care for a MIGS patient postoperatively without being formally designated as the comanaging physician (and are thus not bound by the rules or reimbursement of comanaging) by simply billing the patient or the patient’s insurance directly for the medically necessary services provided. 

Table 1. Current MIGS Procedures

Brand name Procedure CPT/HCPCS Level III Code
FDA approved
CyPass Micro-Stent (Alcon)1,6
Ab interno with cataract extraction; Placed in the angle between the ciliary body and the sclera and terminates in the suprachoroidal space
Ex-Press Glaucoma Filtration Device (Alcon)1,7
Ab externo with or without cataract extraction; Inserted under a conjunctival flap to shunt aqueous from the anterior chamber towards a subconjunctival reservoir
iStent (Glaukos)1,8
Ab interno with cataract extraction; Implanted through the nasal aspect of the trabecular meshwork into Schlemm’s canal
Trabectome (NeoMedix)1,9
Ab interno with or without cataract extraction; Ablates 60° to 120° of trabecular meshwork and the inner wall of Schlemm’s canal
Xen Gel Stent (Allergan)1
Ab interno with or without cataract extraction; Shunts aqueous from the anterior chamber to subconjunctival space
In clinical trials
Hydrus Microstent (Ivantis)1
Ab interno with cataract extraction; Implanted in Schlemm’s canal to increase outflow
InnFocus Microshunt (Santen)1,10
Ab externo with or without cataract extraction; Inserted through a scleral flap into the anterior chamber to increase flow from anterior chamber to subconjunctival space
iStent Supra Micro-Bypass Stent (Glaukos)1,8
Ab interno with or without cataract extraction; Placed in the supraciliary space to increase flow into the uveoscleral space
iStent inject (Glaukos)1,8
Ab interno with or without cataract extraction; Two second-generation iStents are implanted sequentially in adjacent areas of trabecular meshwork
Solx Gold Shunt (Solx)1
Ab externo with or without cataract extraction; Implanted between the anterior chamber and suprachoroidal space to increase outflow

Changes in the Air

But coding for these procedures isn’t set in stone. In fact, an update on coverage was recently published in a proposed/draft LCD by National Government Services, a CMS contractor covering Illinois, Minnesota, Wisconsin, Connecticut, New York, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont.5 National Government Services proposes that one iStent or CyPass device per eye is medically reasonable and necessary for the treatment of mild or moderate open-angle glaucoma when the patient is currently taking an ocular hypotensive medication and the procedure is being performed in conjunction with cataract surgery.4 

As a draft, this change is not yet in place as a formal policy. Should the policy be adopted as proposed, this rule would be in effect for those jurisdictions.

The role MIGS plays within the glaucoma treatment algorithm continues to shift, and differs from the role of more traditional glaucoma surgeries such as trabeculectomy or external aqueous drainage implants. Currently, all other indications are considered not reasonable and necessary.

As these glaucoma treatment options are evolving rapidly, so are the coding procedures that accompany them. But together, glaucoma surgeons and ODs can work closely to bring new technology and better care to patients who suffer from this chronic condition. 

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1. Aetna. Glaucoma surgery. Updated May 30 2017. Accessed June 7, 2017.
2. American Medical Association. CPT process: how a code becomes a code. I CPT code criteria. Accessed May 26, 2017.
3. American Medical Association. CPT® category III codes code descriptors. Accessed Accessed May 25, 2017.
5. Centers for Medicare and Medicaid Services. License for use of physicians’ current procedural terminology, fourth edition (CPT). Accessed May 30, 2017.
6. American Medical Association. CPT Category III Codes Code Descriptors. Accessed June 7, 2017.
7. Alcon Reimbursement Services. Accessed June 7, 2017.
10. Glaukos. Glaukos announces five-year extensions for three category III CPT codes related to micro-invasive glaucoma surgery. March 16, 2017. Accessed June 7, 2017.
9. Fellman R, Mattox C, Vicchrilli S. Modifiers and glaucoma: take this high-pressure quiz. EyeNet. 2013 June: 53.
10. Santen. InnFocus MicroShunt glaucoma drainage system. Accessed June 7, 2017.