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Vision Chart Often Unhelpful
"Damage to my eye? How can that be if I can still see 20/20?"
Seems contradictory, doesn't it? 20/20 vision is the traditional standard for healthy eyesight, but in 2006 we know better.
Truth be told, most folks with fully corrected refractive errors ought to see 20/15, one full line better (smaller) than the 20/20 line. More importantly, there are other, more sensitive techniques to accurately gauge visual function. There are simple tests that can indicate an abnormal condition long before problems pop-up reading the eye chart.
Cold fact: the Snellen eye chart is a very crude means to assess visual performance. '20/20 eyesight' doesn't guarantee that there is no problem.
Let's read between the lines. Delicate nerve fibers transmit the visual image from the eye to the brain. Since so many of the eye's 1.5 million nerve fibers serve the critical central retina (macula), there can be extensive damage beyond the macula and the patient may have no symptoms whatsoever. They may still be able to nail the 20/20 line. The problem comes when irreversible nerve fiber loss eventually involves the macula (and symptoms begin) it may already be too late to make a difference.
Don't freak! Eye doctors know about this cruel trick of nature and have developed useful tests that accurately assess the earliest possible changes. Pupil reactivity, light and color desaturation, contrast sensitivity, and blue-yellow perimetry are just a few techniques that alert the examiner to serious problems in time to help patients preserve crisp eyesight.
Remember, visual acuity is just the beginning of the eye exam!
Related Topics: Innovations in Hearing, 4 Big Advances Changing Medicine
Technorati Tags: visual acuity, vision loss, snellen chart
Seems contradictory, doesn't it? 20/20 vision is the traditional standard for healthy eyesight, but in 2006 we know better.
Truth be told, most folks with fully corrected refractive errors ought to see 20/15, one full line better (smaller) than the 20/20 line. More importantly, there are other, more sensitive techniques to accurately gauge visual function. There are simple tests that can indicate an abnormal condition long before problems pop-up reading the eye chart.
Cold fact: the Snellen eye chart is a very crude means to assess visual performance. '20/20 eyesight' doesn't guarantee that there is no problem.
Let's read between the lines. Delicate nerve fibers transmit the visual image from the eye to the brain. Since so many of the eye's 1.5 million nerve fibers serve the critical central retina (macula), there can be extensive damage beyond the macula and the patient may have no symptoms whatsoever. They may still be able to nail the 20/20 line. The problem comes when irreversible nerve fiber loss eventually involves the macula (and symptoms begin) it may already be too late to make a difference.
Don't freak! Eye doctors know about this cruel trick of nature and have developed useful tests that accurately assess the earliest possible changes. Pupil reactivity, light and color desaturation, contrast sensitivity, and blue-yellow perimetry are just a few techniques that alert the examiner to serious problems in time to help patients preserve crisp eyesight.
Remember, visual acuity is just the beginning of the eye exam!
Related Topics: Innovations in Hearing, 4 Big Advances Changing Medicine
Technorati Tags: visual acuity, vision loss, snellen chart
