What is the Spectacle Free Zone?
Vision is like any biometric measurement, there is a range of normal rather than one single measurement. Google says that the average height of men in 1.7meters. That does not mean that anyone who is taller or shorter is abnormal, there is a range within which most of us are. The range of spectacle free vision is described in the diagram. The numbers are the lenses needed to put the eye into “perfect” focus. Someone whose focus is at point X has a spectacle prescription of -0.50 of myopia and 0.25 of astigmatism.
Wearing this weak prescription would theoretically give the person better vision but in practice it’s so weak that nobody would bother wearing such a pair of glasses. Such people regard themselves as spectacle free. Anyone whose spectacle prescription falls in the blue zone would regard themselves as spectacle free and can see the world without glasses just as well as anyone else. They can perform all visual tasks perfectly with no glasses or contacts. You will notice that there is no sharp edge to the zone but rather there is a gradual transition into the zone were glasses are necessary to see clearly. The purpose of laser refractive surgery is to move your vision from the zone where glasses are necessary into the zone of spectacle free vision. We do not need to get you to the very centre of the zone to be successful. This is where the brain comes in.