Your aunt had shingles near her eye last year. Since then, a small sore on the front of that eye keeps breaking open, and her eye doctor calls it neurotrophic keratopathy. A friend sent her an ad for TB-500, a research peptide tied to thymosin beta-4, and a news story said thymosin beta-4 eye drops “heal the cornea.” Is there trial evidence that thymosin beta-4 drops close these sores?
Only a little. The one completed placebo-controlled trial of a thymosin beta-4 eye drop for this condition enrolled 18 people. More patients healed on the drop than on placebo, six of 10 versus one of eight, but the main four-week result fell short of statistical significance, and the trial was stopped early for a business decision. A larger trial is still recruiting. The drop tested, called RGN-259, is a sterile eye medicine made for trials, not a research vial, and it is not approved anywhere.
Why nerve-damaged corneal sores are hard to heal
The cornea depends on its nerves to keep its surface layer healthy. When those nerves are damaged, the surface can break down and heal slowly, even without much pain. A 2025 Cochrane review lists common causes: infections such as herpes and shingles, diabetes, chemical or physical injury, long-term contact lens overuse, some medicines, and surgery on the eye, brain or sinuses. Left untreated, the condition can scar the cornea and harm vision, so eye doctors often combine lubricating drops, protective contact lenses and sometimes surgery.
Thymosin beta-4 is a small protein the body makes in many tissues. Eye specialists in Detroit described trying it in a 2010 report on long-lasting corneal sores that had not healed. That report had no comparison group.
What the SEER-1 trial found, and how Cochrane rated it
The SEER-1 trial, which began in 2015 and was published at the end of 2022, was the first test against a placebo. It enrolled people with moderate or severe neurotrophic keratopathy who had a sore that would not close. After four weeks, six of 10 people using RGN-259 and one of eight using placebo were fully healed. The authors reported a strong trend, but the main comparison did not reach the usual cutoff for significance. Two weeks after treatment stopped, no RGN-259 patient had a sore return, while the one healed placebo patient did. Comfort scores also improved more on RGN-259, and no serious side effects were linked to the drop.
The company developing the drop helped design the trial, and two authors worked for it. The ClinicalTrials.gov record lists the trial as terminated, with the reason given as a business decision.
The Cochrane team pooled every randomized trial for this condition. For RGN-259, the 18-person study gave a result so imprecise that the range of possible effects ran from much worse to far better than placebo, and the reviewers rated the evidence low certainty. They found somewhat more support for cenegermin, a nerve growth factor drop sold as Oxervate, which is the only medicine approved in the United States for this condition, though that evidence was also rated low certainty. A follow-up thymosin beta-4 trial, SEER-2, plans to enroll about 70 people at sites in the United States and Europe and was still recruiting at its last update.
What your aunt can do now
Keep follow-up visits with her eye doctor or a cornea specialist, because a sore that keeps reopening needs close watching. She can ask whether Oxervate, a protective lens or amniotic membrane treatment fits her case, and whether she might qualify for the SEER-2 trial. Research peptides sold online are not sterile eye medicines and were not what SEER-1 tested; putting them in an eye risks infection on a surface that already heals poorly. Not medical advice.
Sources
- Sosne G et al. 0.1% RGN-259 (thymosin beta 4) ophthalmic solution promotes healing and improves comfort in neurotrophic keratopathy patients in a randomized, placebo-controlled, double-masked phase III clinical trial. Int J Mol Sci, 2022 (PubMed)
- Dunn SP et al. Treatment of chronic nonhealing neurotrophic corneal epithelial defects with thymosin beta 4. Arch Ophthalmol, 2010 (PubMed)
- Kruoch Z et al. Medical and surgical interventions for neurotrophic keratopathy. Cochrane Database Syst Rev, 2025 (PubMed)
- ClinicalTrials.gov: SEER-1, RGN-259 for neurotrophic keratopathy (NCT02600429)
- ClinicalTrials.gov: SEER-2, RGN-259 for neurotrophic keratopathy (NCT05555589)
Related reading
- Dry eyes and thymosin beta-4 drops: what the trials showed
- Oxervate eye drops for neurotrophic keratitis and their fridge logistics
- What TB-500 ads borrow from thymosin beta-4 lab research
By The Everyday Brief. AI-assisted drafting with automated source and editorial checks. Sources fetched 2026-10-23 PT. Not medical advice.