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Medical Forum / General / Vision / May 2006wavefront for glasses or contacts?
My lasik followups consisted of a wavefront analysis and the doctor saying "I nailed your perscription, vision doesn't get any better than that". Would a wavefront analysis be much more accurate in determining a patients vision and the proper corrective lenses, such as contacts or glasses? Is it still common practice to sit a patient behind a machine with multiple lenses and do the "is this better than this" type of routine? Did you not see a phoropter hanging in your doctor's office, and has it really been that long ago that you've had a refraction for eyeglasses? Traditional refraction does a perfectly fine job of correcting lower aberrations of sphere and cylinder, which have large amplitudes and are symmetrical with respect to the visual axis. What's left over are termed "higher order aberrations." Most people have low amounts of higher order aberrations. Refractive surgery, however, increases the magnitude of higher order aberrations. The human eye is optically limited to about 20/15 resolution. The neural limitations are about 20/6. There are tradeoffs of having vision corrected to this level. Wavefront generated contact lenses and eyeglasses are indeed possible, but are impractical at this point in time because of problems of tracking and registration. However, simple RGP contact lenses probably do the best job of correcting higher order aberrations, especially those that are induced by LASIK. DrG On 5/3/06 4:35 AM, in article 1146656113.076384.256840@y43g2000cwc.googlegroups.com, "Dr. Leukoma" <drg@leukoma.com> wrote: > Did you not see a phoropter hanging in your doctor's office, and has it > really been that long ago that you've had a refraction for eyeglasses? [quoted text clipped - 17 lines] > > DrG Not being a vision professional, I have presumed that wavefront correction is merely a new technique for what, in optics, has been called figuring. Figuring for lenses and mirrors has been carried out by a number of techniques for centuries. Knife edge testing is just one of these techniques. To me, the term "wavefront" implies some form of interferometry. I do not know how such interferometry is carried out in optometric practice. How is the reference wavefront, against which wavefront error is measured, obtained. In principle the wavefront of an ingoing beam gets focussed onto and then scattered off of the retina to provide an outgoing wavefront through the eye's optical system. The two wavefronts can then be compared to measure the error. Is that the way it is done? Bill -- Ferme le Bush > On 5/3/06 4:35 AM, in article > 1146656113.076384.256840@y43g2000cwc.googlegroups.com, "Dr. Leukoma" [quoted text clipped - 38 lines] > Bill > -- Ferme le Bush A laser beam is projected into the eye and the outgoing beam is picked up by thousands of tiny lenslets. Or, alternatively, a small beam is measured sequentially. There is an overwhelming amount of information available just by Googling. DrG >> Did you not see a phoropter hanging in your doctor's office, and has it >> really been that long ago that you've had a refraction for eyeglasses? Prior to lasik I had the same glasses for about 8 years, nor had my an eye exam. When my glasses took their final fatal a fatal blow in a basketball game, the edge of the sharp edge fo the frame cut a gash across my eyebrow. 15 stitches later, I figured it was a sign from god to get lasik. I did "see" a phoropter about 3 years ago when I went to a retina specialist pior to lasik. Because of my age, my lasik surgeon asked for a complete retinal exam before he would do the surgery. I haven't had a need to see an eye doc since my lasik followups. So its been about 11 years since I actually had one used. There is a good chance that had you not been wearing glasses the blow would have blinded you; you were lucky the glasses were there and only allowed a cut brow. Everyone playing basketball should be wearing protective eye gear. I would suggest, because of your age, that you see an ophthalmologist since it has been 11 years since your last check. You could have a blinding disease that you are unaware of. Ted. theoretically wavefront could make a slight improvement in visual acuity. the problem is, with wavefront eyeglasses on, if the eye moves off axis in any direction then the wavefront correction is off center. also, with wavefront contacts on, if the lenses move or turn (they do) then the corrections becomes off center. in a nutshell, wavefront lenses won't work. and practically speaking wavefront LASIK hasn't proven to be any better than standard LASIK. >theoretically wavefront could make a slight improvement in visual >acuity. the problem is, with wavefront eyeglasses on, if the eye moves [quoted text clipped - 3 lines] >lenses won't work. and practically speaking wavefront LASIK hasn't >proven to be any better than standard LASIK. But for that occasional total ophthalmoplegic that marches into your office looking for really crisp vision from a new pair of eyeglasses ... maybe we're onto something... ;-) |
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