Eagles and Frogs: Some Eye Shapes Work Better than Others...
The lens in your camera, if it's one of the better ones, will have what we call an aspheric shape. We have learned that this shape produces a sharper and clearer image than if the lens surface was circular. Basically, to make the best image possible, a lens should be steeper in the centre, and flatter towards the edges.
This optically improved lens has what we call a prolate shape, and can be thought of as resembling a bullet tip. The opposite shape, with correspondingly poorer optics, is called oblate and looks like a burger bun.
As shown in the following figure, the human cornea has been modified in order that we can see better, and reduce the optical problems that a circular lens creates. Evolution has changed our eye surface from a circle into an prolate aspheric curve. The eagle takes this improvement even further, hence the expression 'eagle-eyed'. The poor frog has an oblate 'burger bun' cornea, and the term 'frog-eyed' would be no compliment to the quality of your sight!
CK changes the shape of your cornea in the direction of that of an eagle, and will double the depth of field compared to a normal human eye. Unfortunately, standard laser treatment for short-sight or myopia will flatten the central part of your eye and move the optics in the direction of the frog. The loss of quality of vision will be particularly noticeable at night and in low light conditions. To help reduce this problem, newer lasers and wavefront guided treatments are designed to minimize the loss of the prolate, bullet shape of your eyes. CK by design (as shown below) will improve the spherical optics of your vision, by steepening the central area, and simultaneously flattening the cornea further out - eagle eyes!
For more information on CK correction , please see our sister site :
CK treatment at www.CK-treatment.com
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