A new yardstick might yield new thinking in glaucoma
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As a specialty, glaucoma has had no shortage of innovation in recent years.
A new drug, netarsudil, allows much lower pressure reduction than before, but only if patients take it and put up with somewhat red eyes. Don’t like drops? Durysta from Allergan gives patients a slow intraocular dose of bimatoprost for many months of drop-free stability. And soon-to-be-released products like iDose from Glaukos, a travoprost product inserted periodically in the anterior chamber angle, may give lifelong drug delivery. Ocular Therapeutix’s hydrogel intracanalicular or intracameral inserts of latanoprost show similar strong promise, and those are just two of many impending drug delivery products.
The surgical device space in glaucoma is equally promising, including an all-new, safer suprachoroidal device from Sean Ianchulev, the inventor of CyPass, as well as several trabecular bypass devices. And John Berdahl’s Equinox goggles promise to relieve glaucoma associated with decreased intracranial pressure, letting us dial in any IOP we want, at least for a few hours.
What’s missing in glaucoma, though, is the ability to predict the future. All of our current tools, like imaging of the optic nerve, visual field testing and even pressure measurement, assess damage that has occurred in the past or that is occurring right now. We don’t have a yardstick (yet) that accurately predicts future progression of glaucoma.
I believe part of the answer may be psychometrics — the rigorous evaluation of patient sentiments. Sure, we have many valuable questionnaires that ask about compliance and activities (like prolonged Valsalva maneuvers) that might predict optic nerve disease progression. But these work only if patients are honest and have good memories. None of these questionnaires have been rigorously employed to ask diverse questions prospectively, with a later look back quantitatively to see which response is correlated with disease progression.
We have analyzed about 500 eyes prospectively and then looked back to correlate responses to actual progression of disease, measured by optic nerve imaging and visual fields. What we have learned is we need more data, but there are trends that appear promising. Did you know patients who complain less about drop stinging are somewhat more likely to show progression of disease than complainers? This counterintuitive finding, although not statistically significant, hints that those who complain are actually taking their drops. Does this mean we should be surgically more aggressive in people who say that they actually tolerate their drops? We should find out. Best of all, asking questions is simple, has no side effects and can be automated with the growing number of patient engagement tools available.
Trying to better understand the human body, we clinicians are like the three blind men exploring the elephant. One blind man is named physical exam. One is called biometric testing. Perhaps the third should be called psychometrics, asking structured questions. (We don’t have a talking elephant yet, but the analogy works fine for humans.) Each perspective is valuable. Each adds a layer to the truth we seek to help our patients live a better life.
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