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BLOG: Three reasons why MIGS may replace drops as first-line therapy
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The use of minimally invasive glaucoma surgery has grown in the U.S. Here are three reasons why our old standard glaucoma drops may one day be relegated to second-line therapy:
1. Preservatives, preservatives, preservatives. We cornea specialists regularly see elderly glaucoma patients with “refractory dry eye.” What most of these patients actually have is irreversible limbal stem cell deficiency caused by chronic use of preservative-containing glaucoma drops. This trend has become especially alarming since latanoprost became available in generic form.
Have you ever looked at the list of “inactive ingredients” in any of the dozen or so available forms of generic latanoprost? You can access that information for any FDA approved drug at http://dailymed.nlm.nih.gov/dailymed/. The type and concentration of preservatives are relatively unregulated by the FDA but can have profound effects, especially with chronic use, on the ocular surface. Benzalkonium chloride (BAK) is a soap that emulsifies bacteria effectively but does the same thing to the cell membranes of the progenitor (but irreplaceable) limbal stem cells. Daily doses of this and other ingredients on the ocular surface can be damaging over the long term.
2. Compliance. If we had a surgical therapy that worked in 50% of patients, it certainly wouldn’t be first-line therapy. Yet we know from multiple studies that only about 50% of patients have adequate compliance to succeed with topical therapy, so why are eye drops the first (and second) line of therapy for glaucoma? Many believe this conservative approach was a byproduct of the risky and failure-prone surgical alternatives in the 1970s and 1980s, when full-thickness drainage procedures were common yet fraught with complications. In Europe today, surgical therapy is emerging as first-line therapy. This approach deserves consideration, especially with the safety of minimally invasive glaucoma surgery (MIGS).
3. MIGS works and is learnable. A number of procedures are available to fit any surgeon’s skill set, from endoscopic cyclophotocoagulation to the iStent (Glaukos), from trabeculotomy with the Trabectome (NeoMedix) to Visco360 viscodilation of Schlemm’s canal (Sight Sciences). Coupled with cataract surgery, all of these procedures provide meaningful and sustained lowering of IOP and relief from the need for drops. They are reimbursed reasonably, FDA approved and only add a few minutes to cataract surgery. Generally, they don’t increase the risk of hypotony or endophthalmitis. These are truly low-impact surgeries with high-impact results.
One last point: Performing cataract surgery earlier for patients with glaucoma is a trend that most of us agree should grow. It reduces by years the total duration of glaucoma drop therapy and its damaging effects. It eliminates the phacomorphic component of glaucoma and gives us an opportunity to surgically reduce pressure without adding to the patient’s total lifetime surgical risk because we’re simply performing surgery at an earlier stage. It clearly fits into the “what I would do for my sister” category.
The number and growth of companies in the MIGS space speak clearly to the enthusiasm shown by analysts and investors. As doctors, we are always appropriately a shade more conservative in adoption of new techniques, but growth of this promising set of procedures is well supported by their benefits to patients.
Disclosure: Hovanesian reports he is a consultant to Glaukos and Ivantis and is a consultant to and equity holder of Sight Sciences.