Minimally invasive glaucoma surgery (MIGS) provides physicians with a way to lower IOP and reduce or eliminate a patient’s reliance on topical medications with a higher expectation of safety than traditional glaucoma surgical procedures. As such, in pursuit of the tightest IOP control possible, MIGS can be considered earlier.

Doctors and patients may no longer have to wait until the unforeseen progression of glaucoma damages the optic nerve or reduces vision before taking steps to address it. In my practice, what I consider to be “controlled” glaucoma (i.e., a situation in which a surgical procedure need not be considered) has changed with the availability of MIGS.

Prior to MIGS, my definition of controlled glaucoma matched the conventional wisdom. If a patient’s visual field testing was stable, the optic nerve looked good, and the IOP was within the target range at a particular visit, I considered the patient’s glaucoma to be controlled. Even if a patient were complaining about a red, irritated eye, the cost of glaucoma medications, or forgetting to use the prescribed drops, the potential risks associated with a tube shunt procedure or trabeculectomy were high enough for me to stay the course with medical therapy.

This is not so today. My current definition of controlled glaucoma takes into account the patient’s quality of life, as well as any threat of noncompliance with medical therapy. As a result, I’m likely to recommend a MIGS procedure far sooner than I would have recommended any other surgical procedure in order to ensure a patient’s IOP isn’t fluctuating due to non-compliance and to improve his or her quality of life.

A New Way to Define Controlled and Uncontrolled

The many reasons patients may become noncompliant with their prescribed glaucoma medication regimens and the significant frequency at which this occurs are well documented in the literature. Some of these studies shed additional light on this problem and show that patients who go as far as to share a concern with the doctor about the difficulty, inconvenience, discomfort, or costs associated with topical glaucoma therapy tend to be noncompliant.¹

Therefore, when one of my patients expresses this type of concern, I consider his or her glaucoma to be uncontrolled. I deem the patient to be at high risk for noncompliance and consequently for IOP fluctuation, I see a MIGS procedure as a sensible alternative to discuss, and I document all of this in the chart.

I base my updated definition of controlled glaucoma and my increased intolerance of potential IOP fluctuation on analyses from the Ocular Hypertension Treatment Study (OHTS) and the Advanced Glaucoma Intervention Study (AGIS). We know from the OHTS that controlling IOP with topical medications delays or prevents the onset of damage from glaucoma.² An additional common interpretation of the data has been that the difference in proportion of individuals who experienced disease progression in the treated and untreated groups wasn’t overwhelming, approximately 4% vs. 9%, respectively. That’s true for the first few years of the study.

However, around the 5-year mark, the difference between the groups becomes far more pronounced, with far fewer individuals progressing to glaucoma in the treated group (Figure 1).

This drives home for me the importance of taking noncompliance out of the picture. Noncompliant patients are essentially untreated, or at least undertreated, and they may be progressing toward damage from glaucoma, even while our standard means of diagnosis aren’t raising red flags.

From AGIS, we learned that IOP fluctuation increases the likelihood of visual field progression (Figure 2).³ This was seen clearly among patients with relatively lower IOP. Through 5 years, consistently lower IOP with less fluctuation was associated with a lower probability of visual field progression than consistently lower IOP with more fluctuation (Figure 3).⁴ Again, we see that IOP fluctuation, which we would expect with medication noncompliance, puts patients at higher risk.

In addition to reducing the impact of medication noncompliance, rethinking what controlled glaucoma should really mean and turning to MIGS as an option earlier in the course of treatment present opportunities to greatly improve quality of life for patients.

In just one example from my practice, a MIGS procedure changed the life of not only a patient but also her family. The patient needed to use just one drop each night, but was unable to administer it herself. Her daughter or other family member had to there to assist every single evening. While they were doing a good job — their mother’s IOP was consistently where we wanted it to be — I had to ask myself why we would put them through this. I suggested, and the family agreed, to a MIGS procedure, which so far, has rendered the topical mediation unnecessary.

It’s important to realize, too, that similar to cataract surgery and other patients, glaucoma patients increasingly expect their eye doctors to address their pathology without negatively affecting their quality of life. Sparing them when we can from the ocular surface disease issues,⁵ periorbital changes,⁶ and, depending on the drug class, systemic side effects⁷ that are associated with topical IOP-lowering medications is the right thing to do.

New Thinking May Lead to Better Outcomes

The safety of MIGS compared with traditional surgeries has opened the door for us to reconsider many aspects of our approach to treating glaucoma patients. What do we consider controlled versus uncontrolled disease? What is maximal medical therapy? When is the right time to introduce a surgical solution? We may no longer have to handcuff our patients to a lifetime of drops. I suspect we may ultimately determine that relying heavily on topical therapy with all of its potential flaws is riskier than utilizing MIGS to its full potential. Already, this group of procedures includes a variety of options with different mechanisms of action that can be tailored to each patient’s specific situation.

Re-examining our thinking to place importance on issues beyond currently stable IOP and visual field, such as barriers to medication compliance and quality of life, can help us to safeguard patients’ vision more effectively and make their lives easier. GP

References

1. Taylor SA, Galbraith SM, Mills RP. Causes of non-compliance with drug regimens in glaucoma patients: a qualitative study. J Ocul Pharmacol Ther. 2002;18(5):401-409.
2. Kass MA, Heuer DK, Higginbotham EJ, et al. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol. 2002;120(6):701-713.
3. Nouri-Mahdavi K, Hoffman D, Coleman AL, et al. Advanced Glaucoma Intervention Study; Predictive factors for glaucomatous visual field progression in the Advanced Glaucoma Intervention Study. Ophthalmology. 2004;111(9):1627-1635.
4. Caprioli J, Coleman AL. Intraocular pressure fluctuation a risk factor for visual field progression at low intraocular pressures in the advanced glaucoma intervention study. Ophthalmology. 2008;115(7):1123-1129.
5. Fechtner RD, Godfrey DG, Budenz D, Stewart JA, Stewart WC, Jasek MC. Prevalence of ocular surface complaints in patients with glaucoma using topical intraocular pressure-lowering medications. Cornea. 2010;29(6):618-621.
6. Inoue K. Managing adverse effects of glaucoma medications. Clin Ophthalmol. 2014;8:903-913.
7. Servat JJ, Bernardino CR. Effects of common topical antiglaucoma medications on the ocular surface, eyelids and periorbital tissue. Drugs & Aging. 2011;28(4): 267-282.

Dr. Singh practices at The Eye Centers of Racine and Kenosha, WI. Contact Dr. Singh at ipsingh@amazingeye.com.