September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
A fourteen year large scale follow-up study into the distribution of astigmatic axis in Japan. - The result of analysis of approximately 550,000 eyes of Japanese patients by spherical surface power -
Author Affiliations & Notes
  • Masao Yoshida
    Department of Public Health, Kyorin University School of Medecine, Mitaka, Tokyo, Japan
  • Nobuhisa Mizuki
    Department of Ophthalmology, Yokohama City University School of Medicine, Yokohama, Kanagawa, Japan
  • Akira Meguro
    Department of Ophthalmology, Yokohama City University School of Medicine, Yokohama, Kanagawa, Japan
  • Takuto Sakono
    Department of Ophthalmology, Yokohama City University School of Medicine, Yokohama, Kanagawa, Japan
  • Eiichi Okada
    Okada Eye Clinic, Yokohama, Kanagawa, Japan
  • Footnotes
    Commercial Relationships   Masao Yoshida, None; Nobuhisa Mizuki, None; Akira Meguro, None; Takuto Sakono, None; Eiichi Okada, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 1468. doi:
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      Masao Yoshida, Nobuhisa Mizuki, Akira Meguro, Takuto Sakono, Eiichi Okada; A fourteen year large scale follow-up study into the distribution of astigmatic axis in Japan. - The result of analysis of approximately 550,000 eyes of Japanese patients by spherical surface power -. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1468.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : There have been no studies based on large scale research that analyze the distribution of the prescribed astigmatic axis according to spherical surface power. Therefore, we under took a fourteen year large scale follow-up study of 550,000 eyes of Japanese patients who had been prescribed glasses or contact lenses to correct ametropia. The distribution of astigmatic axis, according to spherical surface power, was analyzed.

Methods : The subjects of this study are the 549,985 eyes (glasses: 216,971 eyes, contact lenses: 333,014 eyes) of patients in the 10 to 40 year age range, with astigmatism, which were prescribed glasses or contact lenses to correct ametropia. Prescriptions were given at the Okada eye clinic in Kanagawa, Japan from January, 2001 to December, 2014.

Results : As a result of analysis, among the glasses users, the most common axis was 180° (96,389 eyes (44.4%)), with the next common being 90 ° (30,495 eyes (14.1%)), followed by 170° (15,739 eyes (7.3%)). Also, among the contact lens users, the most common axis was 180° (237,932 eyes (71.4%)), followed by 90° (45,904 eyes (13.8%)), and 160° (18,552 eyes (5.6%)). In this study, spherical surface power was divided into 5 groups (High myopia (S < -6.00D); medium myopia (-6.00D ≤ S < -3.00D); low myopia (-3.00D ≤ S < -0.25D); emmetropia (-0.25D ≤ S ≤ +0.25D); and hypermetropia (S > +0.25D)). The 180 ° and 90 ° axes were analyzed according to spherical surface power. As a result, for both glasses and contact lens wearers, 180 ° was the most common axis in myopia and hypermetropia, however 90 ° was most common in emmetropia. Also, for both glasses and contact lens wearers, as the myopia got stronger the percentage of the 180° axis significantly increased (glasses: P for trend < 0.0001, contact lens: P for trend < 0.01). However, with high myopia, especially in the contact lens wearers, this tendency slows down.

Conclusions : The two main axes, 180 and 90, accounted for 58.5% of the glasses wearers and 85.2% of the contact lens wearers. It is hypothesized that the reason for the slowing of the increase of axis 180° in the high myopia group (especially among contact lens wearers), was because the prescription of astigmatic contact lenses relatively decreased by the correction of spherical equivalent power.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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