 |
In
the 1900s, an astrophysicist named Johannes Hartmann devised a
method of measuring the ray aberrations of mirrors and lenses.
He wanted to isolate rays of light so that they could be
traced and any imperfections in the mirror could be seen.
The Hartmann test consisted of using a metal disk in which
regularly spaced holes had been drilled. The disk or screen
was then placed over the mirror that was to be tested and a
photographic plate was placed near the focus of the mirror.
When exposed to light, a perfect mirror will produce an image
of regularly spaced dots. If the mirror does not produce
regularly spaced dots, the irregularities, or aberrations, of
the mirror can be determined. |
|
Source: Image from the Center for Visual Sciences,
University of Rochester
Around 1971, Dr. Roland Shack and Dr. Ben Platt advanced the
concept by replacing the screen with a sensor based on an
array of tiny lenslets. Today, this sensor is known as the
Hartmann-Shack sensor. Hartmann-Shack sensors are used in a
variety of industries: from the military, to astronomy, and
now in ophthalmology.
|
|
 |
|
Source: Image from ASIC Laboratory Heidelberg
Dr. Josef Bille, of Germany, was the first person to use the
Hartmann-Shack sensor in ophthalmology. Other wavefront
pioneers include Dr. Junzhong Liang and Dr. David Williams.
These doctors built upon the each other_s achievements until a
wavefront device that could be used in a clinical setting, was
developed. Prior to that, the technology was extremely
complex. However, the current wavefront device, developed by
Dr. Williams and Dr. Liang, has been automated resulting in
increased speed and accurac
In 1997, Dr. Liang and Dr. Williams presented a paper at ARVO
(The Association for Research in Vision and Ophthalmology)
that discussed the early clinical results attained with the
wavefront device. At this time, ophthalmologists began to take
a serious look at the possibilities of wavefront technology
for correcting refractive error. The major laser manufactures;
VISX, Bausch & Lomb, and Alcon then approached Drs. Bille,
Williams, and Liang to develop their own wavefront analyzers. |
