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KMID : 1159320190210010071
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Korean Journal of Vision Science
2019 Volume.21 No. 1 p.71 ~ p.79
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Comparing Visual Acuity and Frontal Area Topography in Prescription of Spherical and Toric Soft Contact Lens
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Jeon Seon-A
Jeon In-Chul
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Abstract
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Purpose : The purpose of this study is evaluate the differences in visual acuity and corneal topography when prescribing equivalent contact lenses and toric contact lenses to subjects with corneal astigmatism.
Methods : 39 eyes of 20 adults (22.4±2.0 years old) with astigmatism of ?0.75 D to less than ?2.00 D were enrolled in this study. First, we measured the corneal topography of the naked eye using topography (Tophography, CT-1000, Shin Nippon, Japan) and compared the corneal topography and visual acuity with the equivalent contact lens wear and toric contact lenses, respectively. Secondly, the topography of the cornea was classified into 5 types such as round, oval, symmetric bow tie, asymmetric bow tie, and irregular according to five classification methods such as Bogan et al. We measured the visual acuity of the equivalent contact lens and the toric contact lens using the corresponding sample t test. The frequency analysis showed how the shape of the spherical contact lens and the toric contact lens varies according to the classification method such as Bogan. In this study, contact lens made of somofilcon A material of company C was used.
Results : There were 2.6% round, 61.5% oval, 33.3% symmetric bow tie, 2.7% asymmetric bow tie in the naked eyes. and 2.6% round, 48.7% oval, 28.2% symmetric bow tie, 12.9% asymmetric bow tie, 7.7% irregular in the equivalent contact lenses. 53.8% round, 20.5% oval, 7.7% symmetric bow tie, 5.1% asymmetric bow tie and 12.8% irregular shape appeared in the toric contact lenses. Visual acuity was 0.80±0.06(p<0.050) in the spherical contact lens, 1.00±0.08(p<0.050) in the toric contact lens.
Conclusion : Visual acuity improved significantly when the toric contact lens was worn by an average of 0.2, compared with spherical contact lens with equivalent refractive power in astigmatism. In the corneal topography, the shape of the toric contact lens was significantly larger than that of the spherical contact lens. In order to correct astigmatism accurately, it is suggested that it should be prescribed as a toric contact lens rather than spherical contact lens.
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KEYWORD
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Astigmatism, Contact lens, Topography, Toric, Toric Contact lens
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