Correlations in series of perimetric performance values

The correlation function for consecutive performance (P) values in a material of simple glaucoma is studied. The outcome of perimetry sessions recorded with about 2 min intervals are significantly correlated, whereas those obtained 2 h apart or more are not so. Partial correlations of the right and left P values as well as IOP and P value are estimated and discussed in connection with a statistical model for the sensitivity fluctuations. A slow trend, a random error component and an irregular undulation of sensitivity are discerned. The cause of the fluctuations as well as procedures for reducing the dispersion of performance values are discussed.