Reference values for the production of the aqueous fraction of the tear film measured by the standardized endodontic absorbent paper point test in different exotic and laboratory animal species

Abstract

The aqueous fraction of the tear film and the horizontal palpebral fissure length (HPFL) were measured in exotic and laboratory animals, specifically saffron finches (Sicalis flaveola), chestnut-bellied seed-finches (Sporophila angolensis), red-eared sliders (Trachemys scripta elegans), rats (Rattus norvegicus) and mice (Mus musculus). These species possess small eyes making it difficult to perform the typical Schirmer tear test. Measurement of the aqueous fraction of the tear was performed using the standardized endodontic absorbent paper point tear test (PPTT), accomplished with manual restraint by a single operator. The following results were obtained: saffron finches (n = 42)-HPFL (4.46 ± 0.09 mm) and PPTT (5.10 ± 0.26 mm); chestnut-bellied seed-finches (n = 38)-HPFL (4.77 ± 0.05 mm) and PPTT (4.11 ± 0.34 mm); red-eared sliders (n = 56)-HPFL (8.59 ± 0.08 mm) and PPTT (8.79 ± 0.38 mm); rats (n = 60)-HPFL (6.45 ± 0.09 mm) and PTT (6.18 ± 2.06 mm); and mice (n = 22)-HPFL (3.59 ± 0.27 mm) and PPTT (4.39 ± 1.45 mm).