Preliminary results of an instrument for measuring the optical aberrations of the human eye

The human eye, as our biological vision instrument, contains intrinsic optical defects, referred to as optical aberrations or ametropia. The immediate consequence of such aberrations is poor quality of images formed at the retina. With the advent of more precise pulsed lasers for eye surgery, the development of instrumentation to determine precisely the higher order aberrations of the eye became a crucial chalange. Current instruments available commercially (refractometers) measure only the lower optical aberrations of the eye, i. e., myopia, hyperopia and astigmatism. In the present work we have developed a high resolution refractometer based on the Hartmann-Shack (HS) wave-front sensor. The HS sensor was originally developed for aberration measurements in general optical systems, and is of wide-spread usage in adaptive optics applications such as astronomical telescopes. Preliminary results for a mechanical eye are presented here and the RMSE in dioptric power (D) and cylinder axis (in degrees) were as follows: 0.04D for sphere and cylinder and 4(0) for axis. It is known that refractometers have typical errors of 0.12D diopters for sphere and cylinder and 5(0) for axis. These preliminary results indicate that the HS sensor may be applied successfully on in vivo eyes and that, in the near future, this technology may be available in most eye hospitals and clinics throughout the world, therefore bringing benefits to the general population