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A few years back my Physics professor made a joke that his myopia (i.e., nearsightedness) gave him a "superpower" that allowed him to see close objects much more clearly than someone with typical eyesight. For example, reading small fine print or tiny details on a surface. The physics made sense, as a person with myopia should have a closer near focus point.

Recently, this belief was challenged by a normal-sighted friend. I did some Google-ing and couldn't find any evidence or articles confirming or refuting this belief. All I found was a lot of anecdotal evidence.

My question is: Is this belief correct? Are there any scholarly articles or similarly trustworthy sources confirming this?

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  • $\begingroup$ I have never seen such an article, but I agree with your professor. I used to have 7 degrees of myopia, and it allowed me to see insects very close, in great detail. Now I have operated, and don't have this "superpower" anymore. $\endgroup$ – Rodrigo May 5 '15 at 14:34
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Short answer
Myopes may have some benefit in terms of identifying small objects due to their ability to focus objects nearer to their retina than emmetropes, but only marginally so.

Background
The more myopic you are, the more blurred your distance vision, but the closer up you can see clearly. Hence, myopes have a range of clear vision that is closer to their eyes than emmetropes (normally sighted people) (Triad Publishing).

A young emmetropic adult can focus at an object some 10 cm away, which is defined as an amplitude of accommodation (lens adjustment) of 10 diopters.

A severely myopic eye can be up to minus 6 diopters, bringing the tally from 10 to 16 diopters, meaning you can view something up to 6 cm instead of 10 cm.

Bringing objects closer increases retinal image size and hence increases spatial detail. Going from 10 to 6 cm increases the retinal angle by 10/6 = ~1.7 x, so not even a doubling of the angle.

A random search for a magnifying glass for the visually impaired that aids in reading small print (newspapers etc.) yielded one that magnified 4x (16 diopters):

reading aid
Clip on reading aid. Source: Eschenbach

Microscopes typically have lenses with magnification factors from 4x to 100x.

So in all, myopes do not have microscopic superpowers. A standard magnifying glass for the visually impaired magnifies several times more than a severely myopic eye.

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The changes in image size in myopic eyes are not as large as one would imagine. In fact, they are pretty close and the myops are probably not aware of them until the proper correction is placed which affect the image size in a much greater degree.

You can see on the image that the sizes of retinal images are very similar - the uncorrected image size is shown in Y' row:

(Y'' is an image size with a proper corrective lense)

enter image description here

It is true the near point of accommodation of myopic eye is closer that of emmetropic eye, but it is war away from "superpower" mentioned by the professor.

In addition, the discrimination ability in myopic subjects are greater than of emmetropes, because they able to see smaller points, but at the same time the image quality is affected as well, thus overall image quality is more compromised compared to emmetropic eye.

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