Ripasudil is a prescription eye drop used to lower eye pressure in people with glaucoma or ocular hypertension, and it works through a mechanism unlike any other glaucoma drug on the market. Approved in Japan in 2014 as the world’s first Rho kinase (ROCK) inhibitor eye drop, ripasudil directly targets the eye’s natural drainage tissue to let fluid exit more efficiently. Its story has grown well beyond simple pressure-lowering, though, with emerging research into corneal healing, nerve protection, and surgical recovery making it one of the more versatile ophthalmic molecules under study today.
How Ripasudil Lowers Eye Pressure
Most glaucoma drops work by either reducing the amount of fluid the eye produces or opening an alternative drainage route. Ripasudil does something different. It relaxes the structural scaffolding inside the cells of the trabecular meshwork and Schlemm’s canal, the eye’s main drainage pathway. By breaking down rigid protein filaments inside those cells, the drug makes the tissue more porous and allows aqueous humor to flow out through the route it was always meant to use.1PubMed. Ripasudil hydrochloride hydrate: targeting Rho kinase in the treatment of glaucoma This is called working on the “conventional outflow” pathway, and it matters because dysfunction in that pathway is the primary cause of elevated pressure in the most common form of glaucoma.
Once instilled, ripasudil is absorbed rapidly through the cornea and distributes throughout the eye, concentrating especially in pigmented tissues like the iris and the layer behind the retina.2Mary Ann Liebert, Inc., publishers. Ocular Penetration and Pharmacokinetics of Ripasudil Following Topical Administration to Rabbits Its effects on pressure kick in quickly, but they also wear off relatively fast, which is why the standard dosing is twice a day rather than once.
Approved Uses and Dosing
Ripasudil 0.4% ophthalmic solution is approved in Japan for the treatment of glaucoma and ocular hypertension when other drugs have not worked well enough or cannot be used.3PubMed. Ripasudil: first global approval In practice, that positioning means it is often prescribed as an add-on to existing therapy rather than as a first-line treatment, though it is also used on its own when other medications cause intolerable side effects.
The standard dose is one drop of 0.4% solution in the affected eye, twice daily. The twice-daily schedule reflects the drug’s relatively short duration of action. A one-year clinical evaluation found that ripasudil maintained its pressure-lowering effect over 52 weeks, with average reductions of about 2.6 mmHg at the trough (right before the next dose) and 3.7 mmHg at peak effect when used as monotherapy.4PubMed. One-year clinical evaluation of 0.4% ripasudil (K-115) in patients with open-angle glaucoma and ocular hypertension A separate trial in newly diagnosed open-angle glaucoma patients reported a similar magnitude of pressure reduction, with roughly half the patients reaching their target pressure on ripasudil alone.5INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH. STUDY ON EFFICACY AND SAFETY OF RIPASUDIL HYDROCHLORIDE IN TREATMENT OF NEWLY DIAGNOSED PRIMARY OPEN ANGLE GLAUCOMA
In eyes with high myopia and pathological myopia, a population sometimes tricky to treat, ripasudil still delivered meaningful results. Pressure dropped by about 9% at four weeks and 12% at twelve weeks from baseline when ripasudil was added to existing therapy.6Scientific Reports. Intraocular pressure-lowering effects of ripasudil on open-angle glaucoma in eyes with high myopia and pathological myopia
Using Ripasudil Alongside Other Glaucoma Drops
Because glaucoma often requires more than one medication to reach a safe pressure target, much of the clinical data on ripasudil examines it as an add-on. Two randomized trials tested ripasudil combined with either timolol (a beta-blocker drop) or latanoprost (a prostaglandin analog). When added to timolol, ripasudil provided an additional pressure reduction of about 0.9 mmHg before the next dose and 1.6 mmHg at peak, both statistically significant over placebo. When added to latanoprost, the peak-effect benefit was similar (about 1.4 mmHg), although the trough benefit was smaller and did not reach statistical significance.7JAMA Ophthalmology. Additive Intraocular Pressure–Lowering Effects of the Rho Kinase Inhibitor Ripasudil (K-115) Combined With Timolol or Latanoprost
For patients already on the maximum number of glaucoma drops who still have uncontrolled pressure, ripasudil has shown it can squeeze out additional benefit. A study of such patients found a further 17% reduction in pressure (roughly 2.9 mmHg) after three months of adding ripasudil to everything they were already taking.8PubMed Central. Short-term safety and efficacy of ripasudil as “add-on therapy” in glaucoma patients on maximum tolerable glaucoma medication That margin can be the difference between keeping a patient stable on drops versus sending them to surgery.
Effectiveness in Secondary Glaucoma
Not all glaucoma is the straightforward open-angle variety. Several types of “secondary” glaucoma arise from other eye conditions, and ripasudil has shown particular promise in some of them.
In pseudoexfoliative glaucoma, a form driven by flaky protein deposits that clog the drainage system, ripasudil as an add-on lowered pressure progressively over six months, with reductions reaching about 24% by the end of the study period. Thirty-five of 40 patients hit their target pressure.9PubMed Central. Role of ripasudil as an adjunct treatment in the management of pseudoexfoliative glaucoma
A multicentre study (called ROCK-S) looked at ripasudil across three secondary glaucoma types: uveitic glaucoma, exfoliation glaucoma, and steroid-induced glaucoma. All three groups saw significant pressure drops. Steroid-induced glaucoma showed some of the largest reductions, with a mean decrease of about 9 mmHg at one month and nearly 29% at six months. Uveitic glaucoma responded even more dramatically in percentage terms, with reductions approaching 37% at six months.10Scientific Reports. Intraocular pressure-lowering effects of ripasudil in uveitic glaucoma, exfoliation glaucoma, and steroid-induced glaucoma patients These results matter because secondary glaucomas are often harder to control and can be more aggressive than primary open-angle disease.
The large post-marketing surveillance study that tracked over 3,400 patients in Japan confirmed meaningful pressure reductions across all glaucoma subtypes, including uveitic glaucoma (about 4.7 mmHg reduction), steroid-induced glaucoma (about 5.5 mmHg), and even angle-closure glaucoma (about 3.9 mmHg).11PubMed Central. Ripasudil Hydrochloride Hydrate in the Treatment of Glaucoma: Safety, Efficacy, and Patient Selection
Side Effects You Should Expect
The most noticeable side effect of ripasudil is conjunctival hyperemia, a redness of the white of the eye that occurs because the drug dilates blood vessels on the eye’s surface. This is extremely common. In clinical trials, somewhere between half and two-thirds of patients experience it to some degree.12PubMed Central. Phase 3 Clinical Trial Comparing the Safety and Efficacy of Netarsudil to Ripasudil in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension The redness is most intense about 10 minutes after putting the drop in and typically fades within 60 to 90 minutes. A clinical trial that specifically measured the timeline of this redness found the median offset was 90 minutes, though in many patients it cleared within an hour.13PubMed Central. Evaluation of offset of conjunctival hyperemia induced by a Rho-kinase inhibitor; 0.4% Ripasudil ophthalmic solution clinical trial This side effect is cosmetically annoying but not harmful. Most doctors advise patients to time their drops when they do not need to look presentable for about an hour or two.
More concerning from a long-term adherence standpoint is blepharitis, an inflammation of the eyelids that can cause itching, crusting, and irritation. A study tracking this over two years found that about a quarter of patients developed blepharitis, and the discontinuation rate due to this side effect climbed steadily, reaching roughly 35% by 24 months. Most patients recovered within four weeks of stopping the drug, though a handful needed over eight weeks. Having a history of allergic reactions to other glaucoma drops was a significant predictor of developing blepharitis with ripasudil.14PubMed. Long-term Side Effects Including Blepharitis Leading to Discontinuation of Ripasudil
The large 24-month surveillance study of over 3,300 Japanese patients confirmed a similar overall side effect profile: about 25% experienced some adverse reaction, with blepharitis, conjunctival hyperemia, and conjunctivitis each affecting roughly 6 to 9% of users. Female patients, those with a history of pollen allergies, and those with prior medication allergies were more prone to developing blepharitis.15PubMed Central. Long-Term Intraocular Pressure-Lowering Effects and Adverse Events of Ripasudil in Patients with Glaucoma or Ocular Hypertension over 24 Months
Side effects outside the eye are rare. Reported systemic reactions include occasional constipation, headache, dizziness, and nausea, each affecting well under 1% of patients. One retrospective report did note a drop in blood pressure about a month after starting ripasudil, though severe systemic reactions remain uncommon.16PubMed Central. Ripasudil Hydrochloride Hydrate in the Treatment of Glaucoma: Safety, Efficacy, and Patient Selection – Section: Safety of Ripasudil
How Ripasudil Compares to Netarsudil
The only other ROCK inhibitor approved for glaucoma is netarsudil (marketed as Rhopressa in the United States), so patients and doctors naturally want to know how the two stack up. A head-to-head Phase 3 trial in Japanese patients found that netarsudil dosed once daily lowered average daily pressure by about 4.7 mmHg, compared with 3.0 mmHg for ripasudil dosed twice daily, a difference of roughly 1.7 mmHg in netarsudil’s favor.12PubMed Central. Phase 3 Clinical Trial Comparing the Safety and Efficacy of Netarsudil to Ripasudil in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension A separate comparative study reported a similar gap of about 2.3 mmHg at three months.17PubMed. Netarsudil v/s Ripasudil: The battle of supremacy between two ROCKS-I (rho kinase inhibitors)
Side effects were somewhat less frequent with netarsudil in these trials, though both drugs cause high rates of redness and irritation. The overall incidence of adverse events hovered around 60 to 67% for ripasudil versus about 55 to 60% for netarsudil.12PubMed Central. Phase 3 Clinical Trial Comparing the Safety and Efficacy of Netarsudil to Ripasudil in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension Netarsudil also has its own distinctive side effect profile, including corneal deposits called verticillata, which ripasudil does not cause. Which drug is “better” depends partly on what is available where you live: netarsudil is widely prescribed in the United States and Europe, while ripasudil has deeper clinical experience and broader off-label use in Japan and parts of Asia.
Corneal Healing and Post-Surgical Protection
Beyond glaucoma, ripasudil has generated considerable excitement for its effects on the corneal endothelium, the thin cell layer on the inside surface of the cornea that keeps it clear. When these cells are damaged or diseased, the cornea swells and vision deteriorates. Traditionally the main fix has been corneal transplant surgery. Ripasudil could change that calculus for some patients.
Lab and tissue studies have shown that ripasudil stimulates corneal endothelial cells to migrate and proliferate, particularly in tissue affected by Fuchs endothelial corneal dystrophy (FECD), a progressive condition that is one of the leading reasons for corneal transplants. A single dose of ripasudil ramped up genes involved in cell division, migration, and the pump function that keeps the cornea dehydrated and transparent, while simultaneously dialing down genes linked to harmful tissue scarring.18PubMed. Potential Functional Restoration of Corneal Endothelial Cells in Fuchs Endothelial Corneal Dystrophy by ROCK Inhibitor (Ripasudil) An ex vivo model that mimicked Descemet’s stripping (a surgical technique that removes the diseased endothelial layer to let healthy cells migrate in) showed enhanced cell migration when ripasudil was present.19PubMed Central. Enhanced Migration of Fuchs Corneal Endothelial Cells by Rho Kinase Inhibition: A Novel Ex Vivo Descemet’s Stripping Only Model
A large retrospective study moved this from the lab into real patients. Those treated with ripasudil for corneal edema saw central corneal thickness decrease by about 30 micrometers on average, and visual acuity improved meaningfully. In the FECD subgroup specifically, corneal thickness dropped by about 26 micrometers with significant improvement in vision. Endothelial cell counts stayed stable, suggesting the improvement came from better cell function rather than from new cells replacing dead ones.20PubMed Central. Clinical Evaluation of Ripasudil for Corneal Edema: A Large-Scale Retrospective Cohort Study
Even in routine cataract surgery, where some corneal endothelial cell loss is expected, ripasudil appears protective. A prospective study comparing patients who received ripasudil drops after cataract surgery against controls found endothelial cell loss of just 4.5% in the ripasudil group compared with 12.8% in controls.21PubMed Central. The Protective Effect of Rho-Associated Kinase Inhibitor Eye Drops (Ripasudil) on Corneal Endothelial Cells After Cataract Surgery That kind of difference could be meaningful for patients who already have borderline endothelial cell counts heading into surgery.
Neuroprotection Research
Lowering eye pressure is the only proven way to slow glaucoma, but researchers have long wanted drugs that also protect the retinal ganglion cells, the nerve cells that actually die in the disease. Animal studies suggest ripasudil may have direct neuroprotective properties independent of its pressure-lowering effect.
In a mouse model of normal-tension glaucoma, where damage occurs despite normal pressure, topical ripasudil significantly reduced the death of retinal ganglion cells across the entire retina.22Investigative Ophthalmology & Visual Science. Topical Ripasudil Suppresses Retinal Ganglion Cell Death in a Mouse Model of Normal Tension Glaucoma A separate study using optic nerve crush injury in adult mice found that ripasudil not only prevented ganglion cell death but also stimulated some degree of axon regrowth.23Scientific Reports. Topical ripasudil stimulates neuroprotection and axon regeneration in adult mice following optic nerve injury Lab experiments have also shown that ripasudil protects ganglion cells from oxidative stress, in part by suppressing a damaging enzyme called calpain.24PubMed Central. Neuroprotective effect of ripasudil on retinal ganglion cells via an antioxidative mechanism
All of this is preclinical, meaning it has been demonstrated in lab dishes and animal models but not yet proven in human glaucoma patients. The leap from mouse retina to human clinical outcomes is large, and neuroprotection trials in glaucoma are notoriously difficult to design. Still, the consistency of the animal data across multiple labs and models keeps interest alive, and the fact that ripasudil is already approved for human use as a pressure-lowering drop means it could potentially be studied for neuroprotection without starting the drug development process from scratch.
Other Corneal and Inflammatory Conditions Under Study
The ROCK pathway that ripasudil targets is involved in far more than just eye pressure. It regulates cell movement, inflammation, scar formation, and blood vessel growth throughout the eye. This has led researchers to explore ripasudil for a range of conditions beyond glaucoma, including pseudophakic bullous keratopathy (corneal swelling after certain eye surgeries), iridocorneal endothelial syndrome, and other conditions characterized by corneal endothelial failure.25PubMed Central. A Comprehensive Review of the Role of Rho-Kinase Inhibitors in Corneal Diseases The anti-inflammatory and anti-fibrotic properties of ROCK inhibitors also make them candidates for managing wound healing after corneal procedures, potentially reducing scarring that can cloud vision.
A fixed-dose combination eye drop pairing ripasudil with brimonidine has been evaluated for uveitis-related secondary glaucoma, aiming to simplify the regimen for patients juggling many medications. Early retrospective data suggests the combination effectively lowers pressure in this difficult population, consistent with what has been seen with ripasudil alone.26PubMed Central. Efficacy of ripasudil-brimonidine fixed-dose combination in secondary glaucoma associated with uveitis
Availability Outside Japan
Ripasudil was first approved in Japan in 2014 and remains most widely used there, where it has accumulated the largest body of real-world clinical experience.3PubMed. Ripasudil: first global approval It has since gained approval in several other Asian markets, including India, where a growing number of comparative studies have been conducted. It has not been approved by the U.S. Food and Drug Administration or the European Medicines Agency. In those markets, netarsudil fills the ROCK-inhibitor niche, often in a fixed combination with latanoprost (marketed as Rocklatan or Rhokiinsa).
For patients outside Japan or India who are curious about ripasudil, the practical takeaway is that the class of drugs it belongs to is available in most countries, just in a different formulation. The unique corneal-healing and neuroprotective applications of ripasudil are still investigational everywhere and are not yet part of any country’s approved labeling. Ongoing work on diabetic retinopathy has also been flagged in early-phase trials, broadening the drug’s potential relevance if those studies pan out.