Topical CGRP eye drops significantly improved dry eye symptoms in mice by promoting corneal cell growth and reducing inflammation, suggesting a potential new treatment approach for dry eye disease.
3x daily for 2 weeksTopical CGRP eye drops applied three times daily for two weeks significantly improved all major clinical measures of dry eye in mice, including corneal damage scores and tear stability.
What the researchers found
CGRP expression was significantly reduced in both the cornea and trigeminal ganglion of mice with experimentally induced dry eye disease, establishing a biological rationale for replacement therapy.
In cultured human corneal epithelial cells under stress conditions, CGRP promoted cell proliferation, reduced programmed cell death, and lowered expression of inflammatory cytokines TNF-α, IL-1β, and IL-6.
In live mice with dry eye, topical CGRP applied three times daily for two weeks significantly decreased corneal fluorescein staining scores (a measure of surface damage), increased tear break-up time, and preserved the corneal epithelium. CGRP also reduced infiltrating CD45+ immune cells and inflammatory cytokine expression in the cornea, though it did not significantly affect immune cells in the conjunctiva.
Why it matters
Dry eye disease affects hundreds of millions of people worldwide and current treatments often provide only symptom relief rather than addressing underlying causes. The discovery that CGRP is specifically depleted in dry eye and that replacing it with simple eye drops can both reduce inflammation and promote corneal healing addresses a root cause of the disease rather than just masking symptoms.
How the study worked
The study combined in vitro and in vivo approaches. Human corneal epithelial cells were cultured under hyperosmotic stress to simulate dry eye conditions, then treated with CGRP to assess effects on viability, proliferation, migration, and cell death. For the animal model, desiccating stress was used to induce dry eye in mice. CGRP or albumin control eye drops were applied three times daily for two weeks. Clinical dry eye parameters were measured, and corneal and conjunctival tissues were analyzed using immunostaining and flow cytometry for cell proliferation and inflammatory markers.
What this study cannot tell us
This is a mouse study and results may not directly translate to humans. The dry eye model uses desiccating stress, which mimics only one type of dry eye disease. The two-week treatment period is relatively short, so long-term efficacy and safety are unknown. Sample sizes per group are not specified in the abstract. CGRP did not affect conjunctival inflammation, suggesting its benefits may be limited to the cornea.
How to read the evidence
This is a preclinical study combining in vitro cell culture work with an in vivo mouse model. The evidence is strengthened by the multi-method approach (cell studies, clinical measurements, immunostaining, flow cytometry) and consistent results across endpoints, but remains preliminary as no human data exists yet.
When this study was published
Published in 2025, this is a very recent study representing current research frontiers. Clinical translation of these findings, if pursued, would still require years of development and human trials.
The bigger picture
CGRP is already well-known in medicine — blocking it is the basis for newer migraine treatments (anti-CGRP antibodies). This study reveals the opposite use case: adding CGRP to treat dry eye. It adds to growing understanding that neuropeptides play critical roles in maintaining eye surface health and that disruption of nerve-derived signals may underlie common eye diseases. This neuropeptide-based approach could complement existing anti-inflammatory dry eye treatments.
Questions still open
- Would CGRP eye drops be safe and effective for long-term use in human dry eye patients, given CGRP's known role in pain signaling?
- Could combining CGRP eye drops with existing anti-inflammatory treatments like cyclosporine provide additive benefits?
- Does the lack of effect on conjunctival inflammation indicate CGRP targets a specific subset of dry eye pathology?
Common questions
What is CGRP and why might it help dry eye?
If CGRP-blocking drugs treat migraines, wouldn't CGRP eye drops cause headaches?
Read the original research
Calcitonin Gene-Related Peptide Ameliorates Experimental Dry Eye Disease.
Investigative ophthalmology & visual science, 66(11), 58
Citation
Lin, Zhirong; Verma, Bhupender; Zhu, Shuyan; Zidan, Asmaa A; Najafi, Sheyda; Naderi, Amirreza; Elbasiony, Elsayed; Yin, Jia. (2025). Calcitonin Gene-Related Peptide Ameliorates Experimental Dry Eye Disease.. Investigative ophthalmology & visual science, 66(11), 58. https://doi.org/10.1167/iovs.66.11.58