Abstract
Purpose :
In this study, we describe a method to demonstrate tear film dynamics using pseudo-color images to provide information about underlying mechanisms of tear breakup. Pseudo-color images, superimposing two or three grayscale images in different colors have had many applications in analyzing and displaying scientific findings. Here we show the use of pseudo-color images in studying a particularly complex pattern of tear breakup and dynamics.
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Methods :
Fig. 1 shows the how a pseudo-color image can be generated by superimposition of two grayscale fluorescein images captured at different times after a blink. Fig. 1A was captured 0.2 s after a blink and colored green, while Fig. 1B was captured 6.5 s after the same blink and colored magenta. Fig. 1C shows the superimposition of these two images after alignment of the images using punctate stains indicated by arrows. Grey indicates no intensity change of an area over the time interval, black indicates probable breakup, green indicates dimming, whereas magenta indicates brightening, e.g., convergent flow of the tear film or a dark object has moved out of the area.
Results :
Just after a blink, Fig. 1A, the pattern is dominated by round dark ‘globs’, g, thought to be generated by the expansion of thick globs of lipid; they are often surrounded by a lighter grey halo. Later, Fig. 1B, many vertical ‘squiggles’, s, have formed, together with a horizontal ‘rising tide’, rt.
Fig. 2 shows pseudo-color images for the indicated intervals; color contrast has been increased to emphasize changes in fluorescent intensity. Insets are enlargements of two globs. Magenta borders beneath globs, g, are seen initially, Fig. 2A, indicated thickening of the surrounding haloes, but these borders become narrower, Fig. 2B and eventually disappear, Fig. 2C. While the dark centers of the four upper globs retain their original position and shape, the two lower globs move upwards, Fig. 2A, and give rise to squiggles, Fig. 2C. The squiggles in Fig. 2C, s, are black inferiorly indicating breakup, but are green superiorly indicating thinning, presumably triggered by the inferior breakup. The rising tide, rt, becomes prominent later, Fig. 2D, and is at the level of the top of the squiggles.
Conclusions :
Pseudo-color images demonstrate changes that are not evident from viewing a video recording and so provide additional evidence about tear film dynamics and breakup.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.