Difference between revisions of 20/20 correction
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If you can see 20/15 or even better, this might mean that you are [[overcorrected]] ('''''full correction''''' rounded towards stronger 0.25 D step). (It is not necessarily considered super-human acuity, but it is unnecessary to correct to this level. Also, 20/15 isn't always a good measurement, as some people can sometimes see 20/20 with blur horizon 0.5 D away or even 20/10 with overcorrection on a bright Snellen) | If you can see 20/15 or even better, this might mean that you are [[overcorrected]] ('''''full correction''''' rounded towards stronger 0.25 D step). (It is not necessarily considered super-human acuity, but it is unnecessary to correct to this level. Also, 20/15 isn't always a good measurement, as some people can sometimes see 20/20 with blur horizon 0.5 D away or even 20/10 with overcorrection on a bright Snellen) | ||
It is very difficult or impossible to perform [[Active Focus]] at this level of correction, as there is not enough of a [[blur horizon]] to produce [[stimulus]] - see [[Distance vision]]. | It is very difficult or impossible to perform [[Active Focus]] at this level of correction, as there is not enough of a [[blur horizon]] to produce [[stimulus]] - see [[Distance vision]], unless there is some sort of [[cylinder reduction]] or [[transient astigmatism]] involved. | ||
==See also== | ==See also== | ||
[[20/x vision]] | [[20/x vision]] | ||