A new hydrogel developed by researchers can treat patients in the field before they have access to hospital facilities. (Credit: Niki Bayat et al., Science Translational Medicine)

A reversible, temperature-sensitive temporary seal changes from a fluid to a super-strong semi-solid when applied to the eye. When the patient is ready for surgery to permanently close the injury, doctors can remove the seal by adding cool water.

The material the group was working with for retinal implants was a hydrogel called PNIPAM, poly(N-isopropylacrylamide), which had a unique attribute that made it a natural fit for this application: When cooled, the hydrogel became a liquid for easy application, and when heated, it became a viscous semi-solid with strong adhesion. All that was needed was some tailoring. When an ophthalmologist is ready to repair the eye, the hydrogel can be extracted by applying cool water and converting it back to a less adhesive state.

The research team also developed a special syringe for the hydrogel that would be easy to use on the front lines and capable of quickly cooling the hydrogel before application. The syringe has a cooling chamber filled with calcium ammonium nitrate crystals — the type used in instant ice cold packs. By adding water to the chamber, the crystals activate and cool the hydrogel to operating temperatures within 30 seconds.

The customized seal and delivery device will also reduce the amount of time it takes to close penetrating eye injuries overall.