Fig. 3. The cornea is divided into five areas in order to grade fluorescein uptake. Each area is graded on a scale of 0 to 3, after which the grades are added together to give the final score. Scores greater than three indicate an unstable tear film. (From Lemp MA. Report of the National Eye Institute/Industry Workshop on clinical trials in dry eyes. CLAO J 21:221, 1995 with permission.)