A comparison of the precorneal residence of an artificial tear preparation in patients with keratoconjunctivitis sicca and normal volunteer subjects using gamma scintigraphy

The precorneal residence of an artificial tear preparation has been compared in twelve patients with keratoconjunctivitis sicca (KCS) and twelve normal healthy volunteers. The artificial tear solution was radio-labelled by the inclusion of 1 MBq technetium-99m die-thylenetriaminepentaacetic acid (99Tcm - DTPA), and 25 μl was instilled into one eye only. Deposition of the preparation was followed by gamma scintigraphy. Precorneal clearance of the solution was found to follow bi-exponential kinetics in all subjects with no significant differences in clearance rates between the two study populations. There was also no significant difference in the area under the time-activity profile for the two study groups. This suggests that the reduced reflex tearing and basal lacrimation in KCS patients, indicated by the Schirmer's test, are not important in the clearance of isotonic solutions from the eye surface.