Manoj Motwani, MD
Dr. Manoj Motwani is breaking ground in several areas of Laser Eye Surgery and his peer reviewed studies are included here. If you want further details or wish to contact Manoj Motwani, MD, you may contact him.
Over the past few years there has been a concerted effort on the part of Refractive Surgeons and researchers to increase the number of people achieving 20/20 vision, attempt to get a significant number of these people to get 20/15 (significantly better than 20/20) vision, to decrease or eliminate night glare and halos, and to decrease or eliminate contrast sensitivity loss. This branch of work has been called Custom Ablation or having different ablation patterns dependent on the patient’s prescription and eyes. There have been several directions of research in the custom ablation area, but they have come down to two camps of thought.
Wavefront Guided Ablation
The first school of thought is of wavefront guided ablation. This theorizes that there are microscopic flaws that exist in the human eye as a whole that prevent an eye from seeing better than 20/20. If these flaws could be detected by a wavefront analyzer, a theoretical “fingerprint” of the eye could be created. If these flaws were removed by selective laser ablation, an eye could theoretically make everyone see 20/10, which is close to the absolute possible resolution of the human eye. Unfortunately, this theory never worked out, for several reasons
1. Wavefront detection analyzers just aren’t sensitive enough to provide the information needed to properly image the cornea.
2. Wavefront measurement includes the whole eye rather than just the cornea. Therefore you would be correcting the aberration for the whole eye on the cornea. Those aberrations not on the cornea are not directly corrected but indirectly compensated for which may not lead to the desired result. Furthermore, it has been shown that aberrations throughout an eye cancel each other out. By correcting one aberration, you may uncover another aberration that was canceling it out.
3. Unfortunately, there is an enormous amount of “chatter” giving inaccurate “garbage” information from the analyzers that do the wavefront measurements. Wavefront measurements are not done at the laser, they are done at a separate analyzing machine, and the data then transferred to the laser later on for the procedure.
4. It is dependent on the technical operation for a good reading, and the readings can be difficult to reproduce over multiple measurements.
5. Only a small percentage of the population has significant abnormalities, or what are called higher order aberrations. That would indicate that wavefront ablation is not useful for the other 90+%.
6. The measurement of aberration is for the ENTIRE EYE, and not just the cornea. Correcting whole eye aberrations on the cornea (the only place the excimer laser works) would actually throw off the light refracting system, and also perhaps expose other aberrations.
7. The excimer laser reshaping itself can create new aberrations which cannot be accounted for.
The wavefront guided school of thought has been championed by the VISX system, which received its FDA approval for wavefront guided ablation on the basis of the fact that it was as good as regular non-custom ablation, and nothing in the FDA approval of the Visx Wavefront Guided ablation system actually says that it gets better visual results than their regular system.. Other laser systems in the United States have virtually abandoned the idea of wavefront guided ablation as being effective.