Engineered Peptide Eye Drop Protects Retinal Nerve Cells for Two Weeks After Last Dose in Rats

Researchers engineered a cell-penetrating and melanin-binding peptide (HR97) and conjugated it to sunitinib, then formulated it in a gel-forming eye drop system. They tested this in a rat model of optic nerve injury, measuring retinal ganglion cell survival and intraocular drug concentrations after once-daily topical dosing.

Treating diseases at the back of the eye — like glaucoma and optic nerve damage — usually requires injections directly into the eye, which are painful and require clinic visits. Eye drops are far more convenient, but drugs from drops rarely reach the retina in useful amounts. This peptide-conjugate approach could make effective eye drop treatment for posterior eye diseases a reality, dramatically improving how patients manage chronic conditions.

Getting drugs to the back of the eye via eye drops has been one of ophthalmology's biggest unsolved problems. Most serious retinal diseases currently require intravitreal injections — needles into the eye — every few weeks. Peptide-drug conjugates that bind to melanin and penetrate cells could be the key to making topical eye drops work for posterior segment diseases, which would be a major quality-of-life improvement for millions of patients with glaucoma, macular degeneration, and diabetic eye disease.

This was an animal study in rats, which have much smaller eyes than humans — drug penetration dynamics differ significantly. The study used an optic nerve crush injury model, which may not fully replicate chronic human glaucoma. No human safety or efficacy data exist yet for this formulation.