September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Evaluation of corneal irregularity due to progress of primary pterygium using Fourier harmonic analysis for multiple area diameters
Author Affiliations & Notes
  • Keiichiro Minami
    Miyata Eye Hospital, Miyakonojo, Japan
  • Takashi Ono
    Miyata Eye Hospital, Miyakonojo, Japan
  • Tadatoshi Tokunaga
    Miyata Eye Hospital, Miyakonojo, Japan
  • Shouta Tokuda
    Kagoshima Miyata Eye Clinic, Kagoshima, Japan
  • Atsushi Otani
    Tomey Corporation, Nagoya, Japan
  • Kazunori Miyata
    Miyata Eye Hospital, Miyakonojo, Japan
    Kagoshima Miyata Eye Clinic, Kagoshima, Japan
  • Shiro Amano
    Inoue Eye Hospital, Tokyo, Japan
  • Footnotes
    Commercial Relationships   Keiichiro Minami, None; Takashi Ono, None; Tadatoshi Tokunaga, None; Shouta Tokuda, None; Atsushi Otani, Tomey Corporation (E); Kazunori Miyata, None; Shiro Amano, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 1913. doi:
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      Keiichiro Minami, Takashi Ono, Tadatoshi Tokunaga, Shouta Tokuda, Atsushi Otani, Kazunori Miyata, Shiro Amano; Evaluation of corneal irregularity due to progress of primary pterygium using Fourier harmonic analysis for multiple area diameters. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1913.

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

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Abstract

Purpose : Progress of pterygium increases irregularity of the corneal surface and the increased irregularity results in degradation of visual function. It is important to identify a central area in which the corneal irregularity does not increase due to the progress of pterygium for evaluating the visual functions of the eye. The purpose of the prospective observation study was to evaluate changes in the corneal irregularity due to the progress of pterygium using the Fourier harmonic analysis of corneal topographic data modified to accommodate different diameters of the analysis areas.

Methods : 609 eyes of 465 patients who had pterygium without a history of pterygium excision surgery were enrolled. Mean age was 67.3 (SD: 11.4) years and there were 172 men and 293 women. Best-corrected visual acuity (BCVA) and the corneal topography were measured. Progress rates were calculated as ratios of positions of the pterygium end with respect to the corneal diameters. The topography data were analyzed using the Fourier series harmonic analysis within 1, 2, 3, 4, 5, and 6 mm diameters. Changes in the asymmetry and higher-order irregularity components with the progress rates were evaluated using segmented regression analysis for each analysis diameter.

Results : The progress rate was ranged from 2 to 60% with a mean of 22.2 %, and significantly correlated with the BCVA (P<0.0001, R2=0.065). The asymmetry components showed steep increases when the progress rate exceeded 35.9 to 36.9 % and they did not vary with the analysis diameters. In the higher-order irregularity components, the progress rates of 31.7, 22.5, and 14.8% for the analysis diameters of 1, 3, and 6 mm respectively, showed steep increases at relative starting points, according to the analysis diameters. The amplitudes at the progress rates were within a range of 0.18 to 0.28, which were independent of the analysis diameters.

Conclusions : The segmented regression analysis revealed that the higher-order irregularity components for the series of analysis diameters detected steep increases in the corneal irregularity due to progress of pterygium. The results suggested that the progress of pterygium and its influence on visual function could be evaluated with multiple-area Fourier harmonic analysis.

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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