Low-energy blue light-activated biomaterial can repair damaged corneas

Alternative to surgery

The cornea is the transparent part of the eye that covers the iris and the pupil, and allows light to enter the inside and is further responsible for two-thirds of the eye's focusing power.

As the population increases and ages, thinning of corneas is also on the rise. Transplant operations are the current gold standard to treat thinning corneas, also known as keratoconus.

Keratoconus affects 21 per 1000 men and 18 per 1000 women. The early stages of keratoconus are usually managed with therapeutic contact lenses, while later stages are treated by corneal crosslinking to stabilize remaining collagen and prevent further degradation.

“Our technology is a leap in the field of corneal repair. We are confident this could become a practical solution to treat patients living with diseases that negatively impact corneal shape and geometry, including keratoconus,” Dr. Emilio Alarcon, co-author of the study and an associate professor at the University of Ottawa, Faculty of Medicine, said in a statement.

Seven years of research

The researchers explained that corneal thinning is a significant problem for which there are no effective solutions. Corneal crosslinking, in later stages of the disease, only serves to stabilize already thinning corneas but does not replace the lost collagen.

In their study, the researchers developed light-activated injectable biomaterials which had properties that could be fine-tuned to resemble the human cornea. The team adjusted the concentration of biopolymers and peptides in the hydrogel formulations. 

In the form of a viscous liquid, the material gets injected within corneal tissue after a tiny pocket is surgically created, the researchers explained.

When pulsed with low-energy blue light, the injected peptide-based hydrogel hardens and forms a tissue-like 3D structure within minutes. Dr. Alarcon additionally said that this becomes a transparent material with similar properties to those measured in pig corneas.

Their research took over seven years to reach the publication stage. The study was published in Advanced Functional Materials.

Study Abstract

Many alternatives to human donor corneas are being developed to meet the global shortage of donated tissues. However, corneal transplantation remains the gold standard for diseases resulting in thinning corneas. In this study, transparent low energy photoactivated extracellular matrix-mimicking materials are developed for intrastromal injection to restore stromal thickness. The injectable biomaterials are comprised of short peptides and glycosaminoglycans (chondroitin, hyaluronic acid) that assemble into a hydrogel when pulsed with low-energy blue light. The dosage of pulsed-blue light needed for material activation is minimal at 8.5 mW cm−2, thus circumventing any blue light cytotoxicity. Intrastromal injection of these light-activated biomaterials in rat corneas shows that two iterations of the formulations remain stable in situ without stimulating significant inflammation or neovascularization. The use of low light intensities and the ability of the developed materials to stably rebuild and change the curvature of the cornea tissue make these formulations attractive for clinical translation.