A closer look at how OMDI, a popular IOP-lowering drop, reshapes the anterior eye
A glaucoma medication meant to relieve pressure may also be shifting refractions in the opposite direction. A new prospective observational study from Journal of Glaucoma* reports that nearly one in eight patients developed a clinically meaningful myopic shift within a month of starting omidenepag isopropyl (OMDI; Santen Pharmaceutical, Osaka, Japan) 0.002%, raising fresh questions about how this pressure-lowering agent interacts with the anterior eye.
A pressure-lowering drug with optical baggage
OMDI has earned interest as an alternative for patients who struggle with prostaglandin-associated periorbitopathy (PAP), since it lowers intraocular pressure (IOP) without the orbit-deepening cosmetic changes linked to conventional prostaglandin analogs (PGAs). That makes it attractive for individuals who respond inadequately to standard glaucoma medications or who want to avoid PAP altogether.
But the drug is not without its own profile. Conjunctival hyperemia, punctate keratitis, corneal thickening, myopia, anterior chamber inflammation, macular edema, eye pain, blurred vision and reduced visual acuity have all been reported. Because medication-induced myopia can erode vision and chip away at quality of life, the investigators set out to determine how often this shift occurs and what the eye is doing in those cases.
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Inside the one-month experiment
This prospective observational study enrolled 44 eyes from 44 adults aged 20 years or older, all newly diagnosed with POAG (primary open-angle glaucoma) and treatment naïve. Every patient began OMDI 0.002% at baseline, then underwent the same battery of examinations before and after one month of therapy. Measurements included refractive error, keratometry, corneal topography, optical biometry, visual acuity and IOP.
At the one-month mark, the signal was hard to ignore. Of the 44 eyes analyzed, 13.6% showed a clinically meaningful myopic shift of at least −0.75 D. Across the full cohort, mean refractive error changed from −2.35 to −2.57 D, an average shift of 0.22 D (P = 0.003).
For most patients, the average change was small. But for the subset crossing the −0.75 D threshold, the shift was large enough to affect routine tasks such as driving, distance work or reading street signs, especially for individuals who already live close to the edge of functional vision.
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What changed inside the eye and how quickly
The refractive shift did not appear out of thin air. The anterior segment remodeled in ways that supported a more myopic optical state.
Corneal curvature steepened slightly, with mean K rising from 43.31 to 43.41 D (P = 0.026) and total keratometry from 43.19 to 43.34 D (P = 0.007). Central corneal thickness also increased. At the pupil center, thickness rose from 543.3 to 548.7 μm (P = 0.013). At the apex, it increased from 544.4 to 548.9 μm (P = 0.038).
Lens thickness followed the trend, inching from 4.31 to 4.34 mm (P = 0.004). Meanwhile, the anterior chamber grew shallower, measured at 3.37 to 3.31 mm with Scheimpflug imaging (P < 0.001) and 3.32 to 3.27 mm by optical biometry (P < 0.001).
Axial length and white-to-white diameter stayed unchanged, reinforcing the idea that the action was happening up front rather than through elongation of the globe. These short-term movements painted a picture of the eye leaning forward, optically speaking, as if a muscle behind the scenes was encouraging it inward.
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Ciliary spasm in the background
Based on the full constellation of findings, the authors concluded that ciliary muscle spasm is a plausible underlying mechanism. A forward-moving lens—iris diaphragm, a thickening lens and a bump in corneal power—fit nicely with that hypothesis, even though the study did not directly measure ciliary muscle behavior.
In their conclusion, the authors stated that “the incidence of a myopic shift of 0.75 D or more was 13.6% at one month post-OMDI instillation in patients with [primary open-angle glaucoma]. Ciliary spasm might be the underlying mechanism of myopic shift.”
They added that “the findings of our study will benefit clinicians’ evaluation and treatment decision-making for [patients with primary open-angle glaucoma] undergoing OMDI treatment.”
Bringing it back to the chair
Early refractive changes can color a patient’s perception of a new medication, particularly in glaucoma, where treatment is lifelong and trust matters. A patient who returns after a month of OMDI use reporting blur, less comfortable night driving or headaches during visual tasks may be signaling a true myopic shift rather than vague intolerance.
A quick refraction and a glance at corneal and anterior chamber parameters can help determine whether the drop is the source. In patients who rely heavily on distance clarity, even fractional shifts can influence daily functioning and adherence.
Despite the clean statistics, the study did not identify a simple clinical shortcut for predicting who will shift. No particular age group, baseline refractive profile or ocular parameter at baseline reliably separated stable patients from those who developed myopia.
That’s why expectation management is the most useful tool. A brief discussion about the possibility of short-term refractive change, paired with routine follow-up, may keep patients from abandoning a medication that is otherwise effective at reducing pressure.
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A small sample, an early signal
The authors are careful to note the study’s limitations. Follow-up was limited to one month. The sample size was relatively small at 44 eyes. There was no control group receiving a different glaucoma medication for direct comparison, and the ciliary muscle spasm hypothesis was inferred rather than directly measured.
Even so, the signal is clear enough to inform conversations in the clinic. In a real-world group of treatment-naïve POAG patients, short-term OMDI 0.002% use produced a noticeable rate of clinically meaningful myopic shift, accompanied by consistent anterior segment changes. For glaucoma specialists, that is a useful piece of information to keep in mind the next time a patient says the pressure looks good but the distance chart feels just a little farther away than it used to.
Editor’s Note: This article is based on an epub-ahead-of-print study published in the Journal of Glaucoma.* This content is intended exclusively for healthcare professionals. It is not intended for the general public. Products or therapies discussed may not be registered or approved in all jurisdictions, including Singapore.
*Lee YJ, Choe S, Kim JS. Myopic shift induced by omidenepag isopropyl 0.002% in patients with primary open-angle glaucoma. J Glaucoma. 2025;:ePub ahead of print. Available at: https://journals.lww.com/glaucomajournal/abstract/9900/myopic_shift_induced_by_omidenepag_isopropyl.608.aspx. Accessed on December 3, 2025.