Contact lenses inside the eyes

INASMET Foundation, a member of the TECNALIA Corporation from the Basque Country, is currently carrying out research on intraocular lenses. In fact, INASMET presented two projects at the 17th European Congress on Biomaterials held in Barcelona. Apart from publishing the results of a comparative study on intraocular lenses, they presented a project, currently under development, on intracorneal lenses.

This project started three years ago in collaboration with the Hospital de Donostia, the Department of Organic Chemistry of the University of the Basque Country and the Biomaterials Department at Inasmet.

Intracorneal lenses

As its name suggests, intracorneal lenses are implanted into the cornea. The cornea is the first of the lenses of which the eye is made up, and the most external. The function of these lenses is to correct problems such as myopia, hypermetropia and astigmatism.

The surgical technique in implanting these lenses is very straightforward. Apart from the fact that the operation has to be reversible, using suitable material to make the lenses is fundamental. Inasmet’s involvement in this project specifically targets analysis of materials for the manufacture of the lenses. The main aim is directed at the design, the properties and the production of a material compatible with the cornea.

Biocompatibility

To achieve biocompatibility, biomaterials are used. Biomaterials are materials capable of fulfilling the functions of the tissues and, thus, enabling the creation of organs or part thereof. In this current research, INASMET is analysing a material called PHEMA.

PHEMA is an hydrogel. Hydrogels have the following properties: net structure, elasticity, permeability, water absorption characteristics, etc. Given these properties, it is the habitual material used in lenses today. But when we are dealing with intracorneal lenses, things become complicated, given that the cornea has very special characteristics.

Active material

In order to be compatible with the features of a cornea, using biomaterials is not always enough. This is why, to ensure better biocompatibility, active materials are used.

The biomaterial being investigated at INASMET has a synthetic composition amongst its components. The enzymes secreted by the body in immunological response adhere to this composition and, given that the union is irreversible, these enzymes are inhibited. In this way, the body’s immune response can be halted or weakened. This fact is very important so that the material does not disintegrate, given that the lens has to last for years inside the eye. This technique is known as materials functionalisation and we say that the material is active.

All the research carried out to date has illustrated the potential of the material, but many trials are still to be done before intracorneal lenses are put on to the market. Amongst others, trials have to be carried out to achieve lenses of different dioptres, to perfect the surgical technique involved and the final trials to determine the exact composition of the material.

The project has nevertheless brought together research fields as far apart and, at the same time, as close to each other, as chemistry, materials science and medicine.