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Longitudinal analysis of corneal topography in suspected keratoconus
  1. M Shirayama-Suzuki1,
  2. S Amano1,
  3. N Honda1,
  4. T Usui1,
  5. S Yamagami1,
  6. T Oshika2
  1. 1
    Department of Ophthalmology, University of Tokyo Graduate School of Medicine, Tokyo, Japan
  2. 2
    Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
  1. Professor T Oshika, Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, 305-8575 Japan; toshika{at}


Aims: To examine the incidence of progression of suspected keratoconus to true keratoconus and compare quantitative descriptors of corneal topography between eyes with and without progression.

Methods: 34 eyes with suspected keratoconus were retrospectively reviewed in 34 patients. Their age at the initial examination was 13 to 40 years (24.1 (7.5), mean (SD)), and the follow-up periods ranged from 3 to 10 years (6.0 (2.2) years). Suspected keratoconus was defined as the fellow eye of a clinically apparent keratoconus but that had no slit-lamp signs of keratoconus (Fleischer ring, Vogt striae and Munson sign) with a best spectacle-corrected visual acuity of 20/20 or better. Eyes were monitored for the progression of apparent slit-lamp findings of keratoconus during the follow-up period. Using a Fourier analysis of the corneal topography data, regular astigmatism, asymmetry component and higher-order irregularity component were calculated in the central 3 mm zone. Quantitative descriptors of corneal topography were compared between eyes which progressed to true keratoconus and those which did not.

Results: Five eyes (14.7%) progressed to apparent keratoconus from suspected keratoconus (progression group), and 29 eyes did not (non-progression group). On average, it took 5.2 years for the eyes to develop apparent slit-lamp findings of keratoconus. The cumulative incidence of progression by Kaplan–Meier analysis was 21.5% in 6 years. The asymmetry component and regular astigmatism by Fourier analysis at the initial examination were significantly larger in the progression group than in the non-progression group.

Conclusion: In our retrospective study, approximately 20% of eyes with suspected keratoconus progressed to true keratoconus in 6 years, and these eyes had presented greater asymmetry and regular astigmatism at the initial examination.

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  • Competing interests: None.

  • Funding: Supported in part by Grants-in-Aid 19390439 for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

  • Ethics approval: Ethics approval was provided by the institutional review board of University of Tokyo Hospital.

  • Patient consent: Obtained.