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A. M. Masmali, C. Purslow, P. J. Murphy; The Repeatability of Tear Ferning Test in Healthy Subjects. Invest. Ophthalmol. Vis. Sci. 2009;50(13):543.
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© ARVO (1962-2015); The Authors (2016-present)
Tear ferning (TF) test has been described as a simple clinical test to evaluate the ocular tear film, useful in the diagnosis of dry eye. This study was designed to assess the repeatability (within and between sessions) of the TF patterns obtained from collected tear samples of normal subjects.
16 healthy subjects (11 male, 5 female; mean age 28.8 ± 5.1yrs) were assessed by non-invasive tear break-up time (NIBUT), slit-lamp and completed the symptomatic questionnaire (McMonnies dry eye questionnaire) for exclusion purposes. Stimulated tear samples were collected from the lower tear meniscus of left eyes using glass capillaries during three sessions; 1) 5 separate samples (5 x 10µl) in one morning session; 2) on a second day a 10µl sample was obtained at a morning session (8:30-9:30am); 3) a further 10 µl sample was collected the same afternoon (3:30-4:30pm). From each sample, 5 x 1µl drops were pipetted and dried onto glass slides under controlled room temperature and humidity conditions, then observed using digital microscopy (10x magnification). TF patterns were observed and classified according to Rolando’s grading scales.
In session 1, no significant difference was found between the five separate samples (Friedman Test, p>0.05). TF patterns produced were Type I (38%), Type II (57%) and Type III (5%). There were no Type IV patterns. There was also no significant difference between the TF patterns for the five drops produced for each sample (Friedman Test, p>0.05). 69% of subjects produced identical ferning patterns in all 5 drops: Type I in 36.4% and Type II in 63.6%. Between sessions, no significant differences were found (Friedman Test, p>0.05).
Type II is most commonly observed in young, healthy subjects,and a single sample appears to be representative of a patient. Time of day for collection of sample appears to have little influence on the TF pattern observed. The TF test is still a relatively uncommon test, but has potential for clinical and research use as protocols and quantification methods are further developed.
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