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Simulated Keratometry Repeatability in Subjects with and without Down Syndrome.

Ayeswarya Ravikumar1, Jason D Marsack, Julia S Benoit

  • 1*PhD †PhD, FAAO ‡OD, PhD, FAAO College of Optometry (AR, JDM, JSB, HAA) and Texas Institute for Measurement, Evaluation and Statistics (JSB), University of Houston, Houston, Texas.

Optometry and Vision Science : Official Publication of the American Academy of Optometry
|October 15, 2016
PubMed
Summary

Simulated keratometry measurements using Zeiss Atlas topography showed good repeatability in both individuals with Down syndrome (DS) and controls. However, eyes with DS exhibited approximately 2.5 times greater variability in keratometry values compared to control eyes.

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Area of Science:

  • Ophthalmology
  • Medical Imaging
  • Genetics

Background:

  • Corneal topography is crucial for assessing refractive errors and planning surgeries.
  • Individuals with Down syndrome (DS) may present unique ocular characteristics affecting measurements.
  • Zeiss Atlas topography is a widely used device for corneal imaging.

Purpose of the Study:

  • To evaluate the repeatability of simulated keratometry measurements obtained with Zeiss Atlas topography.
  • To compare measurement repeatability between subjects with and without Down syndrome (DS).

Main Methods:

  • Corneal topography was performed on 140 subjects with DS and 138 controls (aged 7-59 years).
  • Repeatability of keratometry values (steep K, astigmatism, flat K orientation, J0, J45) was assessed using standard deviation, coefficient of repeatability (COR), coefficient of variation (COV), and intraclass correlation coefficient (ICC).
  • Analysis included eyes with at least three valid measures.

Main Results:

  • Keratometry values demonstrated good repeatability in both DS and control groups.
  • Group mean variability was significantly higher in DS eyes (2.5x on average) compared to control eyes for all parameters.
  • Despite higher variability, 91% of DS eyes had steep K and astigmatism variability ≤0.50D, and 75% had flat K orientation variability ≤5 degrees.

Conclusions:

  • Zeiss Atlas topography provides repeatable keratometry measures in individuals with DS, though with increased variability compared to controls.
  • The observed variability in DS eyes is statistically significant but often within clinically acceptable ranges.
  • These findings are important for interpreting corneal topography in individuals with Down syndrome.