For someone whose vision keeps becoming blurrier, distorted or harder to correct with new glasses, the problem may not always be the prescription.
In keratoconus, the cornea — the transparent, normally dome-shaped surface at the front of the eye — gradually becomes thinner and begins bulging outward. As its shape becomes increasingly irregular, light no longer focuses normally, leading to distorted vision, glare and difficulty seeing clearly.
Blurry or distorted vision can, of course, have many causes, so these symptoms do not automatically mean someone has keratoconus. But the condition is particularly important because it often develops in teenagers and young adults, when progressive visual deterioration can affect education, driving, work and independence.
Now, new long-term data from Glaukos Corporation are drawing attention to a treatment that aims to stop that deterioration without removing the cornea’s protective outer surface.
The company reported on October 7 that patients treated once with Epioxa, its epithelium-on corneal cross-linking therapy, continued to show improvement in corneal shape and visual outcomes three years after the original treatment.
That three-year finding needs to be understood correctly.
It does not mean Epioxa is a treatment that “lasts for three years” and then wears off.
Rather, patients received one treatment, were followed over time, and when researchers assessed them three years later, the beneficial changes were still present. No additional intervention was required during the extension study. The available data therefore demonstrate durability through three years; whether that stability persists for five, 10 or more years will require longer follow-up.
For patients, that distinction may be one of the most important parts of the story.
What did the three-year study actually find?
The long-term Phase 3 extension study, known as GLK-202-03, followed patients who had previously received Epioxa during the company’s second pivotal Phase 3 trial.
The extension included 38 treated eyes from 35 patients, with 92% completing their three-year assessment.
At year three, treated eyes showed an average 1.9-diopter improvement in maximum corneal curvature, or Kmax, from their original baseline. In simple terms, the steepened cornea remained flatter and more stable than before treatment — an important objective when treating a disease characterised by progressive corneal distortion.
There were also encouraging vision results.
About 29% of treated eyes gained two or more lines of best-corrected visual acuity, while 20% gained at least three lines compared with baseline.
Glaukos also reported no serious adverse events, treatment-related adverse events or treatment discontinuations linked to Epioxa during the three-year extension period.
Those findings do not mean every patient will see better after Epioxa.
The central purpose of corneal cross-linking is not the same as that of glasses, contact lenses or refractive surgery. Its primary objective is to strengthen the weakening cornea and stop or slow further progression.
That can be particularly important because once keratoconus becomes advanced, restoring useful vision may become much more difficult.
Why is Epioxa considered less invasive?
Traditional corneal cross-linking generally uses an epithelium-off, or “epi-off,” approach.
That means the thin protective epithelial layer covering the front of the cornea is first removed so riboflavin and ultraviolet-A light can penetrate the corneal tissue and create new collagen bonds.
The treatment can be effective, but removing the epithelium creates a temporary corneal wound that has to heal.
Epioxa uses an epithelium-on, or epi-on, approach, meaning that protective outer layer remains in place.
The therapy combines specially formulated riboflavin solutions with supplemental oxygen and pulsed ultraviolet light to achieve cross-linking without routinely stripping away the epithelial surface. Glaukos says this is intended to reduce the pain and recovery burden associated with epithelial removal.
The U.S. Food and Drug Administration approved Epioxa HD and Epioxa on October 17, 2025 for epithelium-on corneal collagen cross-linking in adults and children aged 13 years and older, used with the O₂n System and Boost Goggles.
That approval makes the latest three-year data particularly relevant: the question is no longer only whether an epi-on treatment can work in a controlled pivotal study, but whether its effect appears to remain after patients leave the initial trial period.
So far, the answer from this small extension cohort is encouraging.
What keratoconus can mean in everyday life
The human burden of keratoconus can be easy to underestimate because the eye may appear normal from the outside.
A young person may simply notice that glasses prescriptions keep changing, straight lines appear distorted, lights create glare or halos, or night-time driving becomes increasingly difficult.
As the cornea becomes more irregular, normal spectacles may eventually be insufficient and specialised contact lenses may be needed. In advanced disease, corneal scarring and severe visual impairment can ultimately lead some patients to require a corneal transplant.
A recent global systematic review estimated that more than 23.7 million people worldwide are affected by keratoconus. The highest pooled prevalence occurred among people aged 20 to 29, while estimates in South Asia were comparatively high, although prevalence varied substantially between studies and populations.
Pakistan has its own clinical experience with the disease.
A study conducted at Al-Shifa Trust Eye Hospital followed 71 eyes from 66 Pakistani patients with progressive keratoconus after conventional epithelium-off cross-linking. Their average age was just under 20 years, and progression was halted in 95.8% of cases over three years.
Those findings underline why early diagnosis can matter so much.
The younger the person, the more years they potentially have ahead for an unstable cornea to continue changing.
Does Epioxa cure keratoconus?
No.
Epioxa should not be described as a cure.
It does not necessarily restore the cornea to its original shape, guarantee normal eyesight or eliminate the need for glasses or contact lenses.
Its importance lies in disease stabilisation.
For someone whose cornea is continuing to weaken and distort, preventing further deterioration can itself be a major clinical achievement.
Some patients in the extension study also gained lines of corrected vision, but that should be seen as an encouraging secondary benefit rather than a guarantee for every patient.
The FDA prescribing information also makes clear that treatment is not without side effects.
Across controlled clinical studies, conjunctival hyperaemia, or eye redness, occurred in 31% of treated eyes. Other reported reactions included corneal haze, light sensitivity, eye pain or irritation, increased tearing, dry eye, temporary reduction in visual acuity and other ocular effects.
The three-year extension was also relatively small, involving only 35 patients.
That means the latest results are important but should not be overstated. Larger real-world populations and longer follow-up will be needed to understand whether the benefits remain consistent across different ages, severities of keratoconus and patient populations.
People experiencing unexplained worsening of vision, frequent prescription changes, increasing astigmatism, glare or distorted sight should instead seek evaluation by an ophthalmologist, preferably a corneal specialist, who can perform corneal topography or tomography when appropriate.
That examination can show whether the cornea is developing the characteristic changes associated with keratoconus and whether those changes are progressing.
This matters because cross-linking generally makes the most sense before severe structural damage has occurred.
And that may be the biggest takeaway from the new Epioxa data.
For someone diagnosed with keratoconus at 16, 20 or 25, a successful treatment is not merely about improving a technical measurement on a corneal scan.
It can mean preserving the ability to study comfortably, recognise faces, drive, work and remain independent without watching vision become progressively less predictable.
The three-year result therefore offers something important, but specific: after one Epioxa treatment, the patients followed in this study still showed evidence of corneal stabilisation three years later, without needing another intervention during that period.
It does not tell us the benefit stops at three years.
It tells us that, three years on, the benefit had not disappeared.
And for a disease whose central threat is continued deterioration over time, that may be precisely why these results matter.
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