KERATOMETRIC VARIATION - THE INFLUENCE OF A FLUID LAYER

Variation of keratometric measurements on an approximately spherical s urface on a polymethyl methacrylate (PMMA) button is compared to kerat ometric variation on the PMMA button after the application of an artif icial tear solution. The variation is shown by means of scatter plots in a three-dimensional space, as well as quantitatively in the form of variance-covariance matrices. The wet button showed variances a facto r of more than 1000 times that of the dry button. This suggests that t he precorneal tear film could be an important, often-overlooked contri buting factor to keratometric variation in the case of the eye. Copyri ght (C) 1996 The College of Optometrists. Published by Elsevier Scienc e Ltd