Vision Experts Don't See Eye to Eye in Quest for Perfect Sight
WebMD News Archive
In ophthalmology, wavefront sensors shine a light into the eye that focuses into a point on the retina. The light reflected back from the retina is intercepted by a group of tiny lenses and focused onto a video camera that captures an image, which appears on a screen as a symmetrical grid of points of light. Distortions in the projected grid allow eye surgeons to see exactly where to apply a laser to shave tissue off the cornea to improve vision.
In addition to wavefront sensing, other visionary vision-improving technologies are in the works and may be appearing on the market within the next decade or two, says Applegate, professor of ophthalmology at the University of Texas Health Science Center at San Antonio.
"You've got the baby boomers, all aging. They're all going to have cataract surgery, so look for [plastic lenses] that are [adjustable] once they're put inside the eye," Applegate tells WebMD. "You're also going to have, for people that want to stay away from [corrective] surgery for whatever reason, more custom-made contact lenses. ... You'll see people getting [laser vision correction] after cataract surgery to get rid of [any remaining problems]."
But even if we assume that it's possible to accurately measure and surgically correct all optical errors in a given eye, "there are at least two good reasons to be skeptical that perfect retinal images and perfect vision will follow," writes Larry N. Thibos, PhD, professor of optometry at Indiana University, in the Journal of Refractive Surgery. "First, the ... [minor errors] of eyes are a moving target that may prove difficult, or impossible, to hit. Second, to reap the benefits of correcting [these errors] we must first eliminate ... errors [like astigmatism, where the cornea is irregularly shaped] ... which may be difficult, or perhaps impossible, to achieve."
In addition, our ability to map visual errors currently outpaces the ability to do anything about them, says Ernest W. Kornmehl, MD, director of a refractive surgery center in Brookline, Mass., and clinical instructor in ophthalmology at Harvard Medical School.
"Theoretically, yes, we can get down to between 20/5 and 20/10 vision. However, our ability to measure these [minor errors] that reduce vision is better than the current technology to correct them," he tells WebMD. "It all sounds great, but when you look at the brass tacks it's a little bit more involved. For instance, these aberrations change as we age: the lens changes and the other parts of the eye change, and the question is -- no one knows the answer to this -- will this induce new aberrations? And [if it does,] we'll drop to 20/15 or 20/20, which wouldn't be a bad thing, but we still have to obtain that information."