Tear fluid collection in dogs and cats using ophthalmic sponges

Abstract

Polyvinyl acetal is better than cellulose for tear collection given its superior recovery. Ophthalmic sponges could facilitate routine analysis of tear fluid in dogs and cats, although further studies are needed to evaluate the quality of tears obtained with this method.

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“…Strips were left until the ≥20-mm mark was reached, followed by centrifugation for 2 minutes at 3884 g in a punctured 0.2-mL tube (secured to 2-mL tube) to extract tear fluid for the ferning test. 22 • Tear ferning test: For each sample, 2 µL of tear fluid was deposited on a glass slide inside a 2-mm circular area delineated with a marking pen. Following air drying at room temperature for 10 minutes, 23 each sample was examined with light microscopy (10 X magnification) and classified as grade 1, grade 2, grade 3, or grade 4 according to specific criteria described by Oria and colleagues.…”

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“…244,260,261 For instance, Schirmer strips were used for indepth characterization of proteomics in human 173 and canine tears, 190 and can also successfully recover specific analytes such as cytokines, 200,258 clusterin, 182 and xenobiotics. 211,[213][214][215]244,262 Absorbent sponges exist in different material types such as cellulose, 234,236,263,264 polyvinyl acetal, 209,214,228,236,244,264-266 polyester, 239,242,266 and polyrurethane. 236 A material with hydrophilic and hydrophobic properties (e.g., polyvinyl acetal and polyurethane) 236,264 is generally preferred to optimize the amount of fluid absorbed and the amount of fluid retrieved from the sponge.…”

“…211,[213][214][215]244,262 Absorbent sponges exist in different material types such as cellulose, 234,236,263,264 polyvinyl acetal, 209,214,228,236,244,264-266 polyester, 239,242,266 and polyrurethane. 236 A material with hydrophilic and hydrophobic properties (e.g., polyvinyl acetal and polyurethane) 236,264 is generally preferred to optimize the amount of fluid absorbed and the amount of fluid retrieved from the sponge. For tear fluid collection, the sponge is held against the lacrimal lake by the operator (to minimize reflex tearing), 234,239,242,244,266 or placed beneath the lower eyelid for a given period of time.…”

“…For tear fluid collection, the sponge is held against the lacrimal lake by the operator (to minimize reflex tearing), 234,239,242,244,266 or placed beneath the lower eyelid for a given period of time. 214,236,264 Tear fluid recovered from absorbent sponges can be assayed for selected tear compounds, similar to Schirmer strips.…”

“…257 Last, actual tear fluid should be used whenever possible as the selected matrix for standard calibration curve and quality control solutions, 214,215,272 as the reported surrogates (e.g., artificial tear solution) 279 do not account for chemical interferences and matrix effects that typically occur with a complex biological fluid (e.g., ionization suppression). 272 Blank tears can be collected with absorbent materials before study initiation, retrieving up to 84 µl in 1 min with ophthalmic sponges in dogs 264 and 132 µl in 12 min with successive substitutions of polyurethane mini-sponges in humans. 236…”