Tear film stability has an important role in the quality of vision. A system and method for performing Fluctuation Analysis of Spatial Image Correlation (FASIC) provides for a non-invasive system and method for evaluating the dynamics of the tear film surface using spatial autocorrelation analysis. With FASIC, a series of images are obtained using illumination and a camera. The spatial autocorrelation is calculated for image frames produced by the camera. A sinusoidal background appears in this correlation together with other features. The changes in the sinusoidal background of the spatial autocorrelation is extracted and monitored over time. The spatial period of this sinusoidal background correlates with the thickness of the tear film. In this regard, one is able to derive the tear film thickness from the period of this sinusoidal background.
