Notes:

What about the optical quality of abnormal eyes? Here we show 4 examples of clinically abnormal eyes, each suffering from a different problem. The map in the upper left is from an individual suffering from the "dry eye" syndrome in which the tear film drys out very quickly, leaving the normally smooth cornea rough and of poor optical quality. The upper right map is from an eye with corneal disease called keratoconus, the lower left is an eye that had laser refractive surgery, and the lower right map is from a patient with cataract. Like the normal maps, these pupil maps are irregular and ideosyncratic. However, the difference between hills and valleys of these maps is 10 times larger than for the normal maps. In other words, if the normal maps are like the rolling hills of Bloomington, the clinically abnormal eye is like the Appalachian mountains.

Having measured the shape of the aberrated wavefront we are now in a position to attempt to correct the eye's aberrations and make a perfect retinal image. Conceptually the problem is easy: all we have to do is to flatten the wavefront and make it a perfect plane wave. In this sense the pupil map is a recipe for perfection: retard those places where the wavefront is too far advanced, and advance those places where the wavefront is retarded. That's all we have to do.

Perfecting the eye's optical system thus boils down to a simple procedure: devise a special kind of lens that will flatten the distorted wavefront and make it once again a perfect plane wave. Does such a clever lens exist? Yes, indeed it does. Researchers have been experimenting with several technologies ranging from deformable mirrors to refractive surgery to re-shape the eye's cornea - all aimed at the same outcome of flattening the pupil map. The technology we have been exploring at Indiana University is liquid crystals, like those used in digital watches and laptop computer screens.