Implications of using ED-50 and probit analysis in comparing retinal injury threshold data

David H. Sliney; John Mellerio; Karl Schulmeister

doi:10.1117/12.426711

17 May 2001 Implications of using ED-50 and probit analysis in comparing retinal injury threshold data

David H. Sliney, John Mellerio, Karl Schulmeister

Proceedings Volume 4246, Laser and Noncoherent Light Ocular Effects: Epidemiology, Prevention, and Treatment; (2001) https://doi.org/10.1117/12.426711
Event: BiOS 2001 The International Symposium on Biomedical Optics, 2001, San Jose, CA, United States

Abstract

An indication of the level of uncertainty in laser injury studies relates to the slope of the transformed dose-response curve, or the "probit plot" of the data. The most cited threshold in a laser injury experiment is the point on the probit plot that represents a 50 % probability of injury: the ED-50. This value is frequently referred to as the "threshold," even though some experimental damage points exist below this "threshold." An analysis of any number of example data sets reveals that the slope in most experiments could not be explained by biological variation alone. The optical, thermophysical and biological factors influencing the probit plot are critically analyzed. By theoretically modelling an experiment, small errors in focus are shown to produce a substantial change in the ED-50 and the slope of the probit plot. The implications of plotting spot-size dependence with ED-50 values are shown to be significant, and can lead to erroneous conclusions regarding the apparent spot-size dependence.

Citation Download Citation

David H. Sliney, John Mellerio, and Karl Schulmeister "Implications of using ED-50 and probit analysis in comparing retinal injury threshold data", Proc. SPIE 4246, Laser and Noncoherent Light Ocular Effects: Epidemiology, Prevention, and Treatment, (17 May 2001); https://doi.org/10.1117/12.426711

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