Applying non-toxic stains to the ocular surface (in the form of eye drops) can facilitate evaluation of the tear film, and demonstrate areas of damage on the ocular surface.
Lissamine green is used to highlight ocular surface changes associated with insufficient tear flow and excessive dryness. Devitalized cells and strands of devitalized surface tissue (filaments) can be seen with this stain. A scoring system is used to rate the severity of these changes, and is useful for monitoring Dry Eye treatment over time.
Fluorescein is another dye that disperses in tear film. The longer the fluorescein dye remains evenly dispersed in the tear film, the better the quality of the tear film. The time that it takes for this tear film to “break up” is an important measure of tear film integrity (Tear Film Breakup Time). Fluorescein also allows detection of small areas on the cornea where the lining cells have been lost due to dryness or other forms of damage.
The fluorescein and lissamine green dyes used for ocular staining may cause some mild irritation. A green stain on the surface of the eyes may be present for several hours.
Corneal fluorescein staining correlates with visual function in dry eye patients
Kaido M, Matsumoto Y, Shigeno Y, Ishida R, Dogru M, Tsubota K.
Investigative Ophthalmology and Visual Science
2011 Dec 16;52(13):9516-22. doi: 10.1167/iovs.11-8412.
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Ocular surface staining
Retrieved October 2, 2015 from Johns Hopkins Medicine