Title: Stand by for Implantable Contact Lenses
Author: Martin Drinkwater
Category: UNSW Research


Researchers at the Cooperative Research Centre for Eye Research and Technology (CRCERT) are working on a new method of vision correction. Soon implantable contact lenses could become a real alternative to laser eye surgery and long term spectacle use.

As many as one billion people worldwide suffer from some type of vision problem. Many of these patients are seeking permanent correction to free them from having to wear glasses or contact lenses. Some people undergo laser eye surgery, but this comes with strings attached. It is only suitable for adults because it requires a ‘stable eye’. This means that your eyeball has stopped growing and your prescription has not changed for at least 18 months. Laser surgery also results in loss of corneal tissue.

Researchers at the Cooperative Research Centre for Eye Research and Technology (CRCERT) are working on a new method of vision correction - Implantable contact lenses that could provide a convenient and safe alternative to wearing glasses or having laser surgery.

Diagram of an Implantable Contact Lens (ICL)

A polymer lens is surgically implanted in the cornea. This changes the shape of the corneal surface, thereby achieving the desired refractive correction. The cornea is responsible for refracting light onto the back of your eye. It has five layers: the epithelium, Bowman's membrane, stroma, Descemet's membrane and the endothelium. The outer epithelial layer is a protective coating, just a few cell layers thick.

"Your body naturally regenerates the epithelium if the eye is injured," said Professor Brien Holden, Director of CRCERT. "During the surgical procedure, we remove the epithelium and place the implantable contact lens directly on top of the cleaned Bowman’s membrane. The epithelium then regrows over the contact lens."

layers of the cornea

The synthetic lens is made from a perfluoropolyether (PFPE), a highly porous polymer with fluorine atoms replacing the hydrogen 'ribs' attached to the carbon 'backbone'. During the polymerisation process, nanometre-sized pores are formed in the lens. This allows oxygen to pass through the lens, keeping the cornea healthy and reducing the risk of eye infection.

"We aim to design the implantable contact lens so that it will provide a stable refractive outcome for at least five years," said Professor Holden. "If a patient's prescription changes, the lens can be replaced in a reversible surgical procedure. No permanent damage is done to the crucial stromal tissue. If this process is successful, people could throw away their glasses and contact lenses!"