ABSTRACT
The explosive development of computing power over the last 50 years has already transformed ophthalmic instrumentation, and we speculate that its impact is destined to accelerate. A telling example comes from Smirnov’s landmark paper on the aberrations of the human eye in 1961, published before the potential of computation was clear (Smirnov 1961). Smirnov described a subjective method, similar to but much more sophisticated than Scheiner’s, to characterize not only the eye’s defocus but also astigmatism and higher-order aberrations. Smirnov did not believe that his approach would ever find practical application, stating the following:
Smirnov could not have foreseen the digital revolution that ultimately made possible automated computation of the wave aberration in a small fraction of a second (Hofer et al. 2001). The marriage of optical metrology with modern computational methods presaged the widespread use of Hartmann-Shack and related wavefront sensing methods in the eye. These methods provided a much more complete description of the eye’s monochromatic aberrations than was possible before. Moreover, the wave aberration specifies how light passing through each and every point in the pupil must be advanced or delayed to achieve perfect imaging, thereby providing a map in the pupil plane that indicates where modifications are required to improve vision correction technology. The introduction of accurate wavefront sensing methods raised the possibility of achieving supernormal vision through the correction of higher-order aberrations. Enthusiasm for this idea has waned, at least as applied to the normal population who typically have relatively minor loss in image quality due to aberrations beyond the defocus and astigmatism. Moreover, technologies for vision correction that are commercially available are sufficiently imprecise that higher-order aberration correction is difficult to achieve in any case. Nonetheless, for some patients, such as those with keratoconus or penetrating keratoplasty, the correction of higher-order aberrations remains a very exciting challenge. Yoon et al. have demonstrated the ability to do this with contact lenses, but the technology is not yet available for the typical patient (Sabesan et al. 2007, 2013).
