REPEATABILITY OF CORNEAL TOPOGRAPHY AND THE CLINICAL IMPLICATIONS

Title REPEATABILITY OF CORNEAL TOPOGRAPHY AND THE CLINICAL IMPLICATIONS
Author, Co-Author Timothy Poling, Michel Guillon
Topic
Year
1992
Day
Monday
Program Number
3:45 pm
Room
Great Hall North
Affiliation
Abstract We evaluated three corneal topography units (Computed Anatomy, Inc. TMS-1, EYESYS and Visioptics EH-270) to assess measurement repeatability. Ten consecutive measurements from each instrument were taken for one eye of nine subjects in the following areas of the cornea: central [subscript](Kc), keratometric equivalent [subscript](Kk), mid-periphery [subscript](Km) and extreme periphery [subscript](Ke). Although the data were provided in a slightly different format by each instrument, we were able to compare the data for each of the four areas of the cornea. The repeatability of any given measurement (95% confidence interval) and the minimum number of measurements required to achieve a repeatability of +/-0.05mm were calculated for each instrument as follows: [fix table] REPEATABILITY MINIMUM No. MEASUREMENTS (95% Confidence Interval) (for +/-0.05mm Repeatability) TMS-1 EYESYS EH-270 TMS-1 EYESYS EH-270 [subscript]Kc +/-0.10mm +/-0.12mm +/-0.45mm 4 6 81 [subscript]Kk +/-0.10mm +/-0.10mm +/-0.25mm 4 4 2 [subscript]Km +/-0.17mm +/-0.13mm +/-0.34mm 12 7 47 [subscript]Ke +/-0.22mm +/-0.50mm +/-0.26mm 20 100 28 These results show that the TMS-1 and EYESYS instruments performed similarly and provided the best repeatability for areas [subscript]Kc, [subscript]Kk and [subscript]Km. All of the instruments demonstrated a high degree of variability in the extreme corneal periphery [subscript](Ke). Although the TMS-1 instrument demonstrated good overall performance, we found its usefulness limited since it provides values only for concentric rings, unlike the other two instruments, which provide values for individual meridian
Affiliation of Co-Authors
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