Schirmer strip wetting length varies by commercial manufacturer.

Abstract

To determine whether wetting length of Schirmer tear test (STT) strips varies by commercial manufacturer of test. Ten normal female beagle cross-breed dogs. Schirmer tear test strips from four commercial manufacturers were used to assess wetting lengths in-vitro when exposed to a set volume of water over 1minute. Digital photography was used to assess the total surface area of Schirmer strips from each manufacturer. Schirmer tear test type 1 was performed on normal dogs over 1minute with STT strips from the same four commercial manufacturers in a randomized crossover design. ANOVA was used to detect differences between strips from different manufacturers. Significant differences in wetting length were found between STT strips from different manufacturers in-vitro (P<.0001) and in-vivo (P<.0001). STT wetting lengths for the in-vitro experiments (mean±SD) were 21.2±0.8mm (Amcon Laboratories), 27.8±2.7mm (Merck Animal Health), 30.0±1.7mm (HUB pharmaceuticals), and 31.5±2.3mm (Gulden Ophthalmics). STT wetting lengths for the experiments in live dogs (mean±SD) were 17.5±3.4mm (Amcon Laboratories), 24.8±3.9mm (Merck Animal Health), 26.5±3.7mm (HUB pharmaceuticals), and 24.0±3.9mm (Gulden Ophthalmics). The surface area of STT strips were found to vary between different manufacturers. Schirmer tear test type 1 results in dogs are affected by choice of STT strip commercial manufacturer. It is proposed that guidelines are created for the standardization of future STT strip production.