Lenses in Focus: Free-form progressive lenses

Many presbyopic spectacle wearers who require glasses to read choose to use progressive lenses. These are lenses that have the wearer’s distance prescription in the top of the lens, with the power changing towards the bottom to provide the full reading prescription in the lower third of the lenses. They are a great choice for people who have to wear glasses for both distance and reading tasks, or for people who really only need to use reading glasses but don’t like the inconvenience of putting glasses on to read then taking them off to see in the distance.

Up until a few years ago all progressive lenses were made in much the same way, with the front surface being a generic front surface and the back surface being spherically ground with the wearer’s prescription.

Free-form surfacing is a process capable of producing complex surface shapes on a lens. The shapes are designed by computer, then a robotic single point cutting tool grinds the lens surface to the required shape. The lens is then polished to a high lustre using a flexible polishing pad that is also dynamically controlled by the computer.

So now free-form progressive lenses allow the back surface to be aspherically ground and customised to the wearer’s prescription, giving a much higher optical quality to the lens. Combined with a highly customised front surface, this means wearers of free-form progressives have a wider field of vision for both distance and reading, and give less distortion through the periphery or edge of the lenses. Many people adapt to free-form progressives faster than to traditional progressive lenses.

At Bill Evans Optometrists, we deal with the leading lens manufacturers to deliver the latest free-form lens technology. Carl Zeiss Vision’s GT2 3D lens and Essilor’s Physio 360 are two excellent free-form progressive lenses that we have a great deal of experience with and confidence in prescribing. If you wear progressive lenses, or would like a change from reading glasses, come on in to see if free-form progressive lenses would be suitable for you.