Perfect vision, for most folks, is the capacity to see "twenty-twenty" (20/20).
For the all the curious people out there, what exactly does having 20/20 vision mean? And will laser eye treatment result in this visual acuity?
This is a conventional measurement of optical acuity (or how well you see in the distance). The initial 20 from the 20/20 vision is the measurement (in feet) of the testing distance because the letter chart is normally 20ft away while the second 20 is how faraway the "normal" person can view that size letter at. Therefore, if someone can perceive the "20" (2nd 20) sized letter at 20 feet, their vision is 20/20.
For example, if you get a vision of 20/40, it means that the testing distance is measured at 20 feet for the letter size of 40 while a "normal" person can make out this at 40 feet which is twice the testing distance. However, you can merely make out from 20 feet away, so 20/40 is not quite as satisfactory as 20/20.
Even so, one of the major criteria for passing your usual driving license exam is optic acuity and the standard is 20/40 or better, with both eyes open. Commercial or heavy vehicles require a stricter standard as the visual acuity calls for a vision of 20/40 with both eyes open. Those who need to wear glasses to satisfy this criteria should frequently wear them when on the road driving.
Another example would be commercial pilots, who must experience an optical acuity of 20/20 amongst other things.
If you plan to convert 20/20 to metric units, it would be equal to 6/6. That is, the testing distance is 6 meters.
For most people, success with this kind of treatment means having 20/20 vision after the surgery. Roughly 94% of folks accomplish 20/20 vision or better after refractive procedure and virtually 100% of those can see the 20/30 line of letters, as released by Wagoner, M.D. et. al. in their most recent studies. What this means is that there is a big percentage of people who can now carefully drive without having to wear spectacles after the operation.
This also means that if your sight before surgery is 20/20, you may not get that amount of sight without spectacles after laser eye procedure. This is usually brought about by either an under correction or over correction which leaves patients with a residual Rx. if the expectations are not met during the initial operation, a second treatment can also be performed to improve the vision.
Aside from all these, there are still other criteria that should be considered when assessing the success of refractive operation. Night time haloes, dry eyes, and other optical anomalies can also lessen satisfaction, particularly if they endure for a long time resulting to continuing issues. Assessment of the quality of life and patient satisfaction (not success) rate is said to be at 95% for current laser eye techniques, according to BM Bieler's "Quality of Life After LASIK: The Picture Remains Hazy."
Many folks are very optimistic with the results of laser eye treatment. You really ought to weigh the options and realize the risks. There are risks and there are benefits, but if the benefits outweigh the risk, then refractive operation is for you.
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