Chemical adhesive could help fix transplanted corneas in place

A gel that could glue transplanted corneas onto the eye has been developed by chemists. Using the gel could reduce the number of stitches needed to fix the cornea in place, potentially cutting the risk of infections.

The cornea is the protective coating on the outermost surface of the eye. It can often become cloudy with age, resulting in loss of vision. The first successful human corneal transplant to repair this loss was reported in 1905. It is now one of the most common and successful surgical procedures, with around 11 million operations carried out each year.

Mark Grinstaff and colleagues Pennsylvania State University, University Park, US, have previously developed and tested a gel which can be used to repair scratches and other acute injuries to the cornea. They have now improved the glue by using thiazolidine molecules to make cross-links between the macromolecules in the gel.

’What’s important about this gel is the cross-linking,’ said Grinstaff. ’This gives it the structural strength and integrity for its use as surgical glue.’

’It also degrades over a much longer time period than our original healing gels, which is crucial because the healing time for a corneal transplant can be as long as 6-12 months,’ he adds. Their results were published this month in the journal Bioconjugate Chemistry.  

The gel was tested in vitro by carrying out corneal grafts on human eyeballs donated for medical research. It was used alone, and in combination with stitches, to fix the graft in place. The strength of the seal was then tested by exerting pressure inside the eye and looking for fluid leakage through the incision. The tests showed that although the new glue is not strong enough to use alone, it certainly reduces the number of stitches needed to keep the incision sealed.

Since stitches can put stresses on the wound sites, potentially causing asymmetry in the graft, using glue could lead to more successful transplants.

’[Stitches] can also cause infection and, occasionally, lead to vascularisation,’ adds Grinstaff. ’Our ultimate aim is to replace sutures entirely, which would dramatically improve patient care.’ 

Victoria Gill