Evaluation of ocular surface retention of artificial tears by scintigraphy

To compare the early phase ocular surface retention of five artificial tear formulations using lacrimal scintigraphy.

Sixteen participants (25-42 years) without ocular or systemic disease were enrolled between January 2023 and January 2025, and both eyes were included. Each subject attended three alternate-day sessions and received one Tc-99 m-labeled drop (150 µCi) per eye per session according to predefined formulation pairs: HP guar + sodium hyaluronate (SH) versus saline; trehalose + SH versus dexpanthenol + SH; and SH alone versus polyvinyl alcohol + povidone. Ten-minute dynamic lacrimal scintigraphy was performed following each instillation to evaluate early-phase pre-corneal retention dynamics. Regions of interest were automatically tracked and manually corrected when required. Absolute scintigraphic counts and baseline-normalized 5/0-min and 10/0-min ratios were calculated. A total of 48 dynamic scans were analyzed using linear mixed-effects models with Dunn-Bonferroni post-hoc testing.

Scintigraphic counts decreased significantly over time (p < 0.001), with a significant overall difference among formulations (p = 0.006) and no group × time interaction (p = 0.279). Baseline-normalized ratios similarly demonstrated significant group and time effects (each p < 0.001). HP guar + SH showed greater normalized retention than saline (p = 0.031), and trehalose + SH likewise exceeded saline (p = 0.003). HP guar + SH demonstrated the highest overall retention across formulations and showed a numerical advantage over dexpanthenol + SH (MD = 0.117), though not statistically significant (p = 0.155).

Polymer-hyaluronate combinations, particularly HP guar + SH and trehalose + SH, demonstrated greater early-phase ocular surface retention dynamics compared with saline and several other tested formulations within the observed imaging period. HP guar + SH showed the highest overall retention profile among the evaluated preparations.