Stem-cell treatment improves vision in nine ARK patients

Nine patients arrived at Moorfields Eye Hospital with a condition that had steadily clouded the surface of their eyes. In the first-in-human clinical trial, researchers from Moorfields and University College London treated one eye in each patient with a collagen scaffold carrying two types of stem cells. The other eye was left untreated as a control.

The target was ARK, or aniridia-related keratopathy. The condition follows a deficiency of limbal stem cells, the cells that maintain the border between the white of the eye and the cornea, its clear front surface. Without them, conjunctival tissue grows over the cornea, turning it opaque and forming a thickening layer that progressively worsens vision. ARK is linked to a mutation in the PAX6 gene and affects one in 40,000 to 100,000 people.

The trial measured both the eye's surface and the patients' sight. The treated eyes started with an average ocular surface score of 9.4, a moderate level on the study's scale, then improved to 5.9 after three months and 6.7 after 12 months. The untreated eyes changed little, moving from 8.4 to 8.0 over 12 months.

The clearest result was on the ETDRS vision chart: treated eyes improved by an average of 24 letters, or almost five lines. Those figures come from the nine-patient trial published in JAMA Ophthalmology; a larger study is still needed to test how consistently the treatment works.

And so what, concretely? For people with ARK, the procedure improved vision in this first-in-human trial, although a larger study is still needed. Professor Sajjad Ahmad, a Moorfields consultant and UCL corneal-regeneration professor, said the team is now seeking a larger clinical trial, with a view to the treatment being accepted by the NHS.