NANOTECH CORNEAS

Carbon nanomaterials can be safely implanted into corneal tissue and might be able to provide some biomechanical support to weakened corneas, reports Alfredo Vega MD, MSc, Vissum Corporación Oftalmológica and Universidad de Alicante, Alicante, Spain.

In an in vivo experiment involving 24 eyes of 12 white rabbits, corneas implanted with carbon nanotubes and graphene showed no signs of inflammation or scarring, with a trend towards increased corneal rigidity when examined at three months’ follow-up, Dr Vega told the XXXI Congress of the ESCRS.

Graphene is a nanomaterial composed of a one-atom thick layer of carbon atoms arranged in hexagonal patterns. Carbon nanotubes are allotropes with a cylindrical nanostructure. Carbon nanomaterials have been used in several fields including aviation, telecommunication and robotics as well as for reinforcement of construction materials.

“The properties these materials share include high resistance, 200 times greater than that of steel and almost the same strength as that of diamonds. Moreover, they are inert and almost completely transparent,” Dr Vega said.

In their in-vivo study, the Vissum team implanted half of the rabbit eyes with a balanced salt solution mixed with carbon nanotubes and graphene in a corneal pocket at two different concentrations, 0.1 mg/ml and 1.0 mg/ml. The remaining eyes served as controls. At three months the animals were euthanised, Dr Vega explained.

He noted that in the treated eyes, staining of the corneal stroma samples with blue Alcian showed no signs of fibrous scarring and no alterations in the stromal mucopolysaccharides. It also showed no signs of active inflammation. Masson trichrome staining also showed no inflammation as well as no foreign body giant cell reaction. It also showed a strong adhesion of the tissue in the area surrounding the carbon nanomaterials (see figure).

In addition, biomechanical evaluation of stress-strain of measurements performed on the corneal tissues showed a trend to higher levels of rigidity in those samples treated with carbon nanomaterials compared to the controls.

“These carbon nanostructures are compatible with biological tissues including the cornea and there is enough scientific evidence in the literature that these nanostructures are able to interact with and improve the mechanical properties of the collagen fibres. We are working on improving the distribution within the corneal stroma, which we hypothesise should lead to a strengthening of the tissue,” he said.

Alfredo Vega: alfredovega@vissum.com