Abstract

Background:
The evaluation of aqueous tear film production in laboratory rodents is limited by the small palpebral fissure and globe size.

Aim:
This study aimed to compare aqueous tear film measurements obtained using different commercially available endodontic paper points (EPPs) in laboratory rats.

Methods:
Aqueous tear production was measured in 22 adult Rattus norvegicus using six size-30 EPP brands applied for 15 and 60 s. Brand comparisons were performed at each time point using the Friedman test with multiplicity-adjusted post hoc comparisons. Paired time comparisons (15 vs. 60 s) were analyzed using the Wilcoxon signed-rank test. The effect size was reported as r (Z/√N). The central 90% reference intervals (5th–95th percentile) were calculated for each brand and time point.

Results:
Brand-related differences were identified at 15 s (Friedman χ² = 38.56; p = 2.91 × 10⁻⁷) and 60 s (Friedman χ²= 31.79; p = 6.55 × 10⁻⁶). Measurements were higher at 60 s than at 15 s for all brands (all p ≤ 0.0057; all r ≥ 0.589). The values ranged from 4.39 ± 0.83 to 6.50 ± 1.46 mm at 15 s and from 6.73 ± 1.91 to 10.45 ± 3.00 mm at 60 s.

Conclusion:
EPPs are practical, simple, and minimally invasive tools for evaluating aqueous tear film in laboratory rats; however, to ensure reproducibility and accurate interpretation, brand-specific and time-specific reference intervals are recommended.

Key words: Aqueous tear production test; Endodontic paper points; Laboratory rats; Tear film; Veterinary ophthalmology.