A consequence of getting older is changes to our eyes — not only in terms of vision, but also the increased risk of tearing the retina. Retinal tears happen when the vitreous body inside the eye begins to peel away from the back wall of the eye. As the vitreous body peels away, it can bring parts of the retina with it, creating small tears. Scientists have developed a new gel that can be easily implanted to replace the vitreous body, and it could radically change how torn retinas are treated.

The vitreous body is a clear jellylike substance that helps transmit light to the retina in the back of the eye. Its shape and consistency help keep the layers of the retina pressed together, maintain the shape of the eye and act as a shock absorber to protect the retina when the eye moves quickly. With age, the vitreous body can start to liquefy and lose structure, which pulls on the retina and increases the chance of a tear. Once a tear forms, eye movement can create ripples in the vitreous body, making the tear larger.

During surgery to repair a torn retina, doctors remove the vitreous body and reattach the retina to the back of the eye with lasers or freezing. The vitreous body is then replaced with gas or silicone oil to keep the retina in place until it heals. After a month or two, the gas is absorbed by the body but the silicone oil must be removed.

Scientists have been looking for an alternative replacement for years because of the disadvantages of the current treatment. Both the gas and oil impair vision because they do not refract the light coming into the eye properly. Patients who receive the gas cannot fly, and the oil can cause temporary or permanent glaucoma. Hydrogels have been proposed as possible alternatives, but most absorb water and swell, making them unsuitable.

A new process can create a hydrogel ideal for this treatment. Scientists started with two types of polymers. In separate reactions, they allowed both polymers to start cross-linking to create a gel, but stopped the reaction before it is complete. Then they mixed the two types of polymers together, injected them into eyes and let the reaction complete. The gel that is formed is stable, does not alter vision and does not swell inside the eye. The gel formed within 10 minutes in the eyes of rabbits with detached retinas, and the repaired retinas stayed attached for 410 days with no adverse reactions.

There are still some issues to be worked out, and further safety testing will be necessary. Scientists need to make sure the gel is safe and stable for long-term use. If tests go well, the hydrogel can have other medical applications, including filling gaps in tissues after trauma, tumor removal or infections. The gel may also be augmented by the addition of drugs or other substances that could be used to treat various disorders.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.

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