Tear ferning test in horses and its correlation with ocular surface evaluation

Abstract

Tear ferning test is easy to perform, without risks to the patient. Once standardized for horses, associated or not with the program STEPanizer(©) stereology tool, it is an additional method for evaluating the ocular surface.

Tear ferning test in healthy dogs

“…A larger volume of tear deposited on the slide, as, for example, would be the case with the use of glass rod, may also interfere with the phenomenon of crystallization . However, microcapillaries and micropipettes are the most common methods of tear collection for TFTs according to the medical literature, including in animals …”

“…Thus, these factors were monitored to avoid environmental influences on crystallization. In the present study, we found a mean time of crystallization of 10 min, which is similar to that described in horses . Possible differences in tear composition could lead to a variation in the crystallization range, as well as in tear osmolarity, enabling dogs to show an increased range when compared to other species, besides having values greater than those obtained for humans .…”

“…Indeed, the authors of a study with camels used micropipettes to recover tears . Additionally in dogs, horses, and humans, microcapillaries and other methods (e.g., the platinum spatula in dogs and humans and iron loops in humans) have been used . As it is part of the routine ophthalmic examination for dogs and because it is a useful method for obtaining tear film for the evaluation of protein profiles, the Schirmer strip was used as a collection method …”

“…Although the scale developed by Rolando has been applied to horses and dogs and the scale proposed by Masmali et al . was applied to camels, there is no record in the veterinary medicine literature of a grading scale specifically for animals .…”

Evaluation of lacrimal production, osmolarity, crystallization, proteomic profile, and biochemistry of capuchin monkeys’ tear film

“…Tear ferning grading scales are based on previous studies with humans, and studies assessing TFTs in animals are scarce. 2,38,39 To compensate the absence of a specific scale and reference values, two grading scales were taken into account, the Rolando and Masmali scales. In this study, the operators observed differences in human and CM's tear film samples, as the crystal angulation and thickness, which could be attributed to variations in tear composition, sampling method, and temperature and environmental humidity.…”