Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mean shape of the human limbus   Purpose: To characterize the mean topographical shape of the human limbus of
a normal eye and ascertain whether it depends on age and refractive power.
Setting: Academic institution. Design: Prospective case series. Methods: 74
subjects aged from 20 to 84 years and with no previous ocular surgeries were
included in this study. The left eye was measured four times with a corneo
scleral topographer (Eye Surface Profiler). From the raw anterior eye height
data of each measurement, topographical limbus was demarcated and fitted in
three dimensions to a circle, an ellipse and a Fourier series. Root mean square
error (RMSE) was calculated to evaluate the goodness of fit. In addition, white
to white (WTW) corneal diameter was taken from the readings of the measuring
device and compared with the topographical limbus. For statistical analysis,
subjects were grouped as young and older, and also according their equivalent
sphere correction. Results: From the considered models, second order Fourier
series resulted in the most accurate model to describe the shape of the human
limbus. The difference between the topographical limbus diameter and the WTW
corneal diameter amounted on average and standard deviation to 0.33 mm and 0.24
mm. Statistically significant differences among eye quadrants were found. No
statistically significant difference in horizontal and vertical meridian
between age groups (P=0.71 and P=0.082, respectively) or between myopes and
emmetropes (P=0.78 and P=0.68, respectively) were found. Conclusions: Human
limbus is not symmetrical and its shape is subject dependent but not related to
age and eye refractive power.

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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: q-fin