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KMID : 1011420160210020099
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Journal of Korean Ophthalmic Optics Society
2016 Volume.21 No. 2 p.99 ~ p.108
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Comparison of Tear Distributions by the Corneal Eccentricity when Fitted with Spherical and Aspherical RGP Lenses
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Kim Ji-Hye
Kim So-Ra
Park Mi-Jung
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Abstract
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Purpose: The present study was aimed to compare the tear volume and distribution by corneal eccentricity when fitted with spherical and aspherical RGP lenses.
Methods: Spherical and aspherical RGP lenses were fitted in best alignment on a total of 77 subjects (136 eyes) in their twenties and thirties without any ocular disease or ocular surgery experience. The tear volume was analyzed by estimating the concentration of tear stained with fluorescein in the center of RGP lens as well as at the mid-peripheral and peripheral areas, and the difference of tear distributions was analyzed according to corneal eccentricity.
Results: Tear distribution from the center to the peripheral area was not significantly different when spherical RGP lenses were fitted on the corneal eccentricities of e < 0.38 and 0.68 ≤ e, indicating the relatively even tear distribution compared with other corneal eccentricity. In the case of aspherical RGP lenses, the difference of tear distribution between the central and peripheral areas was smaller than spherical RGP lenses. The significant difference of tear distribution according to RGP lens design was observed in the corneal eccentricity of 0.48 < e < 0.68. In other words, more even tear distribution was shown when aspherical RGP lenses were fitted on the cornea with eccentricity of 0.48 ≤ e < 0.68 and spherical RGP lenses were fitted on the cornea with eccentricity 0.68 ≤ e. Furthermore, tear volume in the mid-peripheral area increased with higher corneal eccentricity.
Conclusions: The results suggest that the appropriate selection of RGP lens design according to corneal eccentricity is necessary since tear volume and distribution by the regions of spherical and aspherical lenses are affected by corneal eccentricity.
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KEYWORD
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Corneal eccentricity, Tear volume, Tear distribution, RGP lens fitting, RGP lens design
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