Wavefront Aberration & its Applications in Ophthalmology and Optometry
Jichang He， MD， New England College of Optometry， Boston， USA
Forty years have passed since wavefront aberration was first measured in the human eye by Smirnov in 1961. Interest in wavefront aberration， however， did not accelerate until fast measurement with high precision was achieved in 1996. Currently， there are high expectations for clinical applications of wavefront aberration for ophthalmologists and optometrists， but development of specific techniques to provide these expected applications is only in its infancy.
The overwhelming emphasis of wavefront application in ophthalmology during last couple years has been focused on refractive surgery. Elevated wavefront aberrations have been reported frequently in patients with LASIK as well as PRK. The refractive surgery induced wavefront aberrations were observed in both myopia and hyperopia with both lower order aberrations and higher order aberrations. With the aim of minimizing the induced aberrations and correcting the original aberrations for patients， wavefront guided refractive surgeries have been performed during last two years. Improvement in controlling wavefront aberration was found with the wavefront guided techniques， but satisfaction has not yet been achieved. Serious challenges to the benefits of a prefect correction with refractive surgery have emerged from scientific researches on the basis of problems dealing with aging， accommodation and chromatic aberrations. Now， the question of how to optimize wavefront guided refractive surgery is a serious question， even though the technique is still far from reaching a perfect correction.2588
Since last year， increased wavefront aberrations have been observed for patients with cataract and glaucoma surgeries in comparing with normal subjects. Differences between post-operative wavefront aberrations for cataract patients with corneal incisions and those with scleral incisions have also been found this year. Improvement of these surgeries is implied by these studies， but techniques for accomplishing such improvement have not yet been developed.
Adaptive optics combined with the ophthalmoscope is a new hope for ophthalmologists and optometrists to obtain a better retinal image. Even though such a system is currently available in the laboratory for scientific research， development of this type of instrument in clinical application has not yet been completed.
In optometry， the relationship between wavefront measurement and conventional refractive testing has been recently examined. Wavefront aberrations were found to provide a good prediction of the conventional refractive error. Contact lenses were found to affect wavefront aberrations but have different effects with different types of contact lenses. While soft contact lenses were found to induce more wavefront aberrations， mainly higher order aberrations， RGP contact lenses reduce lower order aberrations in the myopic eye.
Overall， clinical applications of wavefront techniques in both ophthalmology and optometry are now rapidly developing with increased exploration predictable in the near future.
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