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Related Experiment Videos

A simple and effective video keratometric system

H Igarashi1, M Kojima, S Igarashi

  • 1Howe Laboratory of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, USA.

Acta Ophthalmologica Scandinavica
|August 1, 1995
PubMed
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A new personal computer video keratometry system precisely measures corneal curvature and astigmatism using placido disk rings. This cost-effective system offers high accuracy comparable to commercial photokeratometers for eye analysis.

Area of Science:

  • Ophthalmology
  • Biomedical Engineering
  • Optometry

Background:

  • Accurate corneal curvature measurement is crucial for refractive error correction.
  • Existing photokeratometry systems can be expensive and complex.
  • Placido disk-based systems offer a non-invasive method for corneal topography.

Purpose of the Study:

  • To evaluate the precision of a novel personal computer-based video keratometric system.
  • To assess the system's ability to measure corneal radius of curvature and astigmatism.
  • To compare the system's performance against a commercial photokeratometer.

Main Methods:

  • A Maloney surgical keratometer projected placido disk rings.
  • A video camera attached to an operating microscope captured ring images.

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  • Images were processed on a personal computer using a custom analysis program.
  • System precision was validated against a commercial photokeratometer in 18 eyes.

    • Main Results:

    • Principal meridian values showed minimal differences (< 0.04 mm) compared to controls.
    • 83% of eyes (15/18) had measurements within 0.03 mm of control values.
    • Corneal astigmatism and cylindrical axes were measured with high accuracy (within 0.12D and 5 degrees, respectively).

    Conclusions:

    • The developed personal computer video keratometry system demonstrates sufficient precision for measuring corneal radius of curvature.
    • The system accurately quantifies corneal astigmatism and cylindrical axes.
    • This adaptable system can analyze placido disk rings from various sources, offering a precise and potentially cost-effective diagnostic tool.