Is a standalone iStent Infinite (Intraocular implant) procedure medically necessary for a patient with primary open-angle glaucoma?

Standalone iStent Infinite is NOT Medically Necessary for This Patient

The standalone iStent Infinite procedure should be denied for this 49-year-old patient with early-stage primary open-angle glaucoma because she has not exhausted appropriate medical therapy or less invasive surgical options, and the device lacks robust evidence for standalone use in patients who are not on maximum tolerated medical therapy or have not failed prior glaucoma surgeries. 1

Critical Deficiencies in Medical Management

Medication Timing Error Compromising Efficacy

• The patient is taking latanoprost (Xalatan) at 6-7 AM instead of the prescribed bedtime dosing, which significantly reduces its IOP-lowering effectiveness since prostaglandin analogs are specifically designed for once-daily evening administration to maximize IOP reduction during the critical nocturnal period 1
• This timing error alone could account for inadequate IOP control and must be corrected before considering any surgical intervention 1

Insufficient Medical Therapy Optimization

• The patient is currently on only 2 medication classes (prostaglandin analog + fixed combination beta-blocker/alpha-agonist), when 3-4 medication classes are typically required before surgical intervention is considered appropriate 1
• A third-line agent, specifically a topical carbonic anhydrase inhibitor (brinzolamide or dorzolamide), has not been added and can reduce IOP by an additional 15-20% 1
• The American Academy of Ophthalmology guidelines emphasize that effective medical approaches exist for lowering IOP and should be exhausted before proceeding to incisional surgery 2

Missing Treatment Steps in the Glaucoma Management Algorithm

Selective Laser Trabeculoplasty Not Attempted

• Selective laser trabeculoplasty (SLT) should be considered before any incisional surgery, as it provides effective IOP reduction with minimal risk and is a well-established intermediate step 1
• The American Academy of Ophthalmology guidelines support laser trabeculoplasty as an appropriate treatment option before proceeding to incisional glaucoma surgery 2

Inadequate Documentation of Current IOP Control

• While historical peak IOP values of 38 mmHg OD and 37 mmHg OS are documented, the current IOP control status on the existing (albeit improperly timed) medication regimen is not provided 1
• Target IOP is stated as "high teens" but actual recent IOP measurements are not included in the clinical information 1

Evidence Limitations for Standalone iStent Infinite

FDA Approval and Guideline Restrictions

• The original iStent received FDA approval only for implantation in combination with cataract extraction in patients with mild to moderate open-angle glaucoma, not as a standalone procedure 1
• The American Academy of Ophthalmology guidelines explicitly state that MIGS procedures, including iStent devices, are "commonly combined with phacoemulsification" and have "limited long-term data" 1

Research Evidence Applies to Different Patient Population

• The 2023 study demonstrating effectiveness of standalone iStent infinite specifically enrolled patients with open-angle glaucoma "uncontrolled by prior incisional or cilioablative surgeries or maximum tolerated medical therapy (MTMT)" 3
• This patient has neither failed prior glaucoma surgeries nor is she on maximum tolerated medical therapy—she is on only 2 medication classes with improper timing of one medication 1, 3
• The study population had a mean age of 71.9 years and mean baseline IOP of 23.4 mmHg on 3.1 medication classes, which differs substantially from this 49-year-old patient on 2 medication classes 3

Quality of Evidence Concerns

• A 2021 systematic review concluded there is "very low-quality evidence" that iStent treatment provides benefit, with insufficient data to support standalone use 1
• While more recent studies show promise for standalone use, they consistently enrolled patients who had exhausted medical therapy or failed prior surgeries 3, 4, 5

Disease Severity Does Not Justify Premature Surgery

Early-Stage Disease with Decades of Potential Progression

• The patient has early-stage glaucoma with "early superior thinning" on OCT, not advanced disease requiring urgent surgical intervention 1
• At age 49, this patient faces decades of potential disease progression, making preservation of surgical options critical for future management 1
• Proceeding to surgery without optimizing medical therapy exposes the patient to surgical risks unnecessarily 1

Surgical Complications Risk in Young Patient

• The American Academy of Ophthalmology guidelines emphasize that MIGS has "limited long-term data" and "modest IOP reduction" with pressures "typically in the mid to upper teens" 1
• While recent studies show favorable safety profiles, complications including peripheral anterior synechiae, improper stent placement, and need for additional procedures have been reported 6

Recommended Treatment Algorithm Before Surgical Consideration

Step 1: Correct Medication Administration (4-6 weeks)

• Instruct patient to take latanoprost at bedtime (QHS) as prescribed, not in the morning 1
• Verify proper medication instillation technique and adherence 1
• Reassess IOP control after 4-6 weeks of properly timed medications 1

Step 2: Add Third-Line Medical Therapy (if needed)

• Add topical carbonic anhydrase inhibitor (brinzolamide or dorzolamide) to the regimen if target IOP is not achieved with corrected medication timing 1
• Consider fixed-combination products to improve adherence if needed 2

Step 3: Consider Selective Laser Trabeculoplasty

• Perform SLT before incisional surgery, as it provides effective IOP reduction with minimal risk 1
• SLT is appropriate when medical therapy is insufficient but before proceeding to incisional procedures 2

Step 4: Reassess for Surgical Candidacy

• Only after exhausting medical therapy (3-4 medication classes properly administered) and considering SLT should standalone MIGS be reconsidered 1
• At that point, if cataract is present, combined cataract surgery with iStent would be more appropriate than standalone procedure 2

Common Pitfalls to Avoid

• Do not proceed to surgery based solely on historical peak IOP values without documenting inadequate control on optimized medical therapy 1
• Do not accept patient-reported medication timing as adequate when it contradicts prescribing instructions—this is a correctable cause of treatment failure 1
• Do not skip intermediate treatment steps (medication optimization, SLT) in favor of incisional surgery in a young patient with early disease 1
• Do not rely on standalone MIGS device studies that enrolled patients with failed prior surgeries or maximum medical therapy when your patient has neither 3, 4