Other research groups are also working on replacement lens materials, but Fetsch believes her material is different in several ways. One significant difference, she says, is reversible disulfide bonds. "This means that after forming the gel, we can reduce the bonds, liquefying the gel again so that it can be injected into the lens capsular bag." Once in the bag, the material reforms to a gel under natural physiological conditions.

One advantage of this is that only a very small injection hole is required to place the lens material in the bag, thus avoiding the common surgical technique of cutting a slit to insert a replacement lens. Fetsch says the hole would be small enough that stitches would not be required after the lens material is placed in the capsular bag.

Fetsch is hopeful that animal testing can begin in one year. But first, the researchers have to improve the materials' refractive index the degree at which it refracts light, which is key to how well you can focus with the material.

"Right now, in this particular system, that's a little low," Fetsch admits. "It's not good enough to be able to see more than blurry. But it's something we think we can bring up with just simple modifications." Other scientists have been successful in improving the refractive index in similar soft gels, according to the researchers.

The material the research group is using to form the reversible bonds acrylamide is a known neurotoxin, but Fetsch doesn't think that will be a problem because the acrylamide is polymerized.

"It sounds ludicrous to put [acrylamide] in the body, but the idea is that polyacrylamide when it's in long chains is not toxic to the body as far as we know," Fetsch says. Additionally, before injection, thorough washing of the material would get rid of any traces of acrylamide, she adds.

The polymerization process also
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8-Sep-2003