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C. A. Johnson, M. Wall, K. R. Woodward, C. K. Doyle; A Continuous Probability Scale for the Humphrey Matrix Frequency Doubling Technology (FDT) Perimeter. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5296.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a continuous probability scale, using percentiles, for the Humphrey Matrix perimeter and evaluate its utility in evaluating normal results and glaucomatous visual field plots.
Probability plots of age-corrected (adjusted to an average 45 year old individual) sensitivity for the left and right eyes were produced from contrast sensitivity measures (Humphrey Matrix 24-2 test procedure) obtained from 329 normal observers between the ages of 18 and 87 (mean = 46). These continuous functions for each of the 55 locations were then applied to independent separate groups of normal control subjects (n=53) and patients with glaucomatous visual field loss (n=112).
The relationship between sensitivity in dB (ordinate) and percentile (abscissa) for the 329 normal observers is presented below for four locations (15 degrees for X and Y eccentricity) for the right eye in each of the four visual field quadrants. The normal controls subjects demonstrated findings that were within statistically predicted values, whereas the extent, slope and boundaries of glaucomatous visual field losses were better characterized by the continuous probability scale. Examples will be presented.
Continuous probability plots for frequency doubling sensitivity values for the Humphrey Matrix perimeter provide a means of illustrating a gradient of sensitivity variations rather than discrete (e.g., 5 ,2 ,1 and 0.5% probability levels) intervals, which can be of assistance for visual field interpretation.
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