The Need For a Better Implant

The first-generation implants were a major improvement for those wearing an artificial eye, but they were unable to deliver a natural movement to the artificial eye. This lack of movement was a major obstacle to restoring a natural appearance, which made the adjustment to wearing an artificial eye much more difficult.

The first-generation implants also tended to drift (migrate) in the orbit and were often rejected (extruded) by the body, making further surgery necessary. These problems inspired researchers to seek a better orbital implant.

Hydroxyapatite: The Natural Choice

The goal of a more natural appearance was finally achieved with the help of a natural material: ocean coral. A remarkable similarity was noticed between the porous structure of certain coral species and that of human bone.

Soon after this discovery, a method was developed to transform the mineral in coral to match that of human bone, known as hydroxyapatite. (abbreviated as HA)

This naturally derived material has both the porous structure and the chemical structure of bone. Thus, the tissues of the body will accept, even grow into these naturally derived hydroxyapatite implants, and they essentially become a "living" part of the body. This is in contrast to artificially made hydroxyapatite, or the porous materials like porous polyethylene (Medpor) or aluminum oxide (Bioceramic ) that do not have these properties.

Physical Comparison of Bone and HA
Scanning electron microscope image (SEM) of human cancellous bone		Scanning electron microscope image (SEM) of coralline hydroxyapatite

The First Hydroxyapatite Orbital Implant ...