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QUEST [Watson and Pelli, Perception and Psychophysics, 13, 113-120 (1983)] is an efficient method of measuring thresholds which is based on three steps: (1) Specification of prior knowledge and assumptions, including an initial probability density function (p.d.f.) of threshold (i.e. relative probability of different thresholds in the population). (2) A(More)
PURPOSE Interferometric methods have considerable potential for studying the thickness of layers of the human tear film and cornea because of their ability to make noninvasive, accurate, and rapid measurements. However, previous interferometric studies by Prydal and Danjo yielded tear thickness values near 40 and 11 microm, respectively, considerably(More)
Spearman rank-order correlations (R) were made between the color-mixture threshold, spatial contrast sensitivity, and flicker sensitivity measurements of 38 patients with a variety of optic nerve disorders. Patients had to satisfy the following criteria: greater than 0.5 log unit loss of chromatic or achromatic sensitivity (compared to age-matched normals),(More)
Panel tests of color vision (eg FM100-Hue test) lack a common quantitative method for the scoring of cap arrangements. We describe a scoring method applicable to all panel tests that makes use of a novel technique to analyze test cap data, namely the calculation of a moment of inertia from the Color Difference Vectors (CDVs) of any arrangement pattern.(More)
We consider model problems for the tear film over multiple blink cycles in limits that yield a single equation for the tear film; the single nonlinear partial differential equation that governs the film thickness arises from lubrication theory. The two models that we consider arise from considering the absence of naturally occuring surfactant and the case(More)
We study the relaxation of a model for the human tear film after a blink on a stationary eye-shaped domain corresponding to a fully open eye using lubrication theory and explore the effects of viscosity, surface tension, gravity and boundary conditions that specify the pressure. The governing non-linear partial differential equation is solved on an overset(More)
PURPOSE We developed a mathematical model predicting dynamic changes in fluorescent intensity during tear film thinning in either dilute or quenching regimes and we model concomitant changes in tear film osmolarity. METHODS We solved a mathematical model for the thickness, osmolarity, fluorescein concentration, and fluorescent intensity as a function of(More)
PURPOSE The purpose of our study was to test the prediction that if the tear film thins due to evaporation, rather than tangential flow, a high concentration of fluorescein in the tear film would show a greater reduction in fluorescent intensity compared to a low concentration of fluorescein due to self-quenching at high concentrations. METHODS Tear film(More)
PURPOSE Tear evaporation should increase fluorescein concentration, causing fluorescence dimming from self-quenching for high but not low fluorescein concentration. This prediction was tested and compared to the predicted effect of "tangential flow" that fluorescence dimming should be similar for high and low concentrations. METHODS A custom optical(More)