[The modified Schirmer tear test in birds--a method for checking lacrimal gland function]

The Schirmer tear test (STT) is an important component of the complete ophthalmic examination in mammals for evaluating lacrimal function. However, no STT reference values for birds have been published to date. 255 ophthalmologically healthy birds (42 different species form seven orders) were tested using a 1-minute STT I (without topical anaesthesia, reflex secretion), STT II (with topical anaesthesia, basal secretion) and as a modification STT III (measurement under isofluran/oxygen, inhalation anaesthesia, a precaution to minimize examination induced stress) using standardized 5-mm-STT strips as well as--under consideration of the size of the palpebral fissure--strips trimmed down to 2 and 4 mm. Mean values (+/- SD) for STT I and STT II were 3.2 +/- 2.7 to 7.5 +/- 2.6 mm/min and 1.7 +/- 1.4 to 4.5 +/- 2.8 mm/min respectively in Psittaciformes (using 4 mm strips), 4.1 +/- 2.7 to 14.4 +/- 7.2 mm/min and 2.0 +/- 1.7 to 4.2 +/- 3.1 mm/min in Falconiformes and 10.7 +/- 4.0 to 11.5 +/- 5.4 mm/min and 3.6 +/- 1.7 to 5.9 +/- 3.1 mm/min in Accipitriformes (using 5 mm strips). Due to the lack of a glandula lacrimalis Strigiformes showed STT levels below 3 mm/min. STT III values were between those of STT I and STT II in Falconiformes and Accipitriformes but not in Columbiformes. On the basis of these results the STT will become an important component of the bird specific ophthalmologic examination procedure allowing more sophisticated examination of lacrimal gland associated avian eye disorders.