J Korean Ophthalmol Soc.  2008 Aug;49(8):1317-1322. 10.3341/jkos.2008.49.8.1317.

Analysis of Refractive Error and Corneal Asphericity in Elementary School Students in Ilsan City

• Kim SY
• Choi JH
• Park YH
• Chang BS
• Mah KC
• Lee YC

• KMID: 2211738
• DOI: http://doi.org/10.3341/jkos.2008.49.8.1317

Abstract

PURPOSE
To determine the relationships among refractive error, corneal asphericity, and axial length in elementary school students.
METHODS
One hundred eleven eyes from 56 subjects were included in this study. All subjects underwent cycloplegic refraction corrected to the spherical equivalent. Axial length was measured, and corneal topography was performed. Corneal asphericity was assessed using eccentricity (e) calculated according to the formula Q=-e2. The relationship among spherical equivalent, asphericity, and axial length was determined using a linear regression model.
RESULTS
Subjects were between 8 and 12 years of age (mean, 9.99+/-1.33). The average spherical equivalent was -1.38+/-2.08D (-7.13~2.63D), the average axial length was 23.84+/-1.17 mm (20.10~26.37 mm), and the average corneal asphericity was -0.29+/-0.10 (-0.55~-0.07). An increase in myopia was positively correlated with an increase in axial length (p<0.0001). The degree of myopia was negatively associated with corneal asphericity (p=0.019). An increase in axial length was related to an increase of negativity in asphericity (p=0.012).
CONCLUSIONS
An increase in myopia was correlated with an increase in axial length. As the degree of myopia and axial length increased, corneal asphericity became more prolate. A longitudinal study with more subjects is required to validate these results.

Keyword

Asphericity; Axial length; Myopia; Refractive error

MeSH Terms

Corneal Topography
Eye
Humans
Linear Models
Myopia
Phosmet
Refractive Errors
Phosmet

Figure

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  Figure 1. Conic sections of asphericity, Q.

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  Figure 2. Relationship between the axial length and spherical equivalent refractive error.

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  Figure 3. Relationship between the corneal asphericity and spherical equivalent refractive error.

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  Figure 4. Relationship between the corneal asphericity and axial length.

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  Figure 5. Frequency distributions of corneal asphericity (Q) values. The mean corneal asphericity(±standard deviation) for 111 subjects was -0.29±0.10 (-0.55~-0.07).

Reference

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