Agreement and repeatability of four different devices to measure non-invasive tear breakup time (NIBUT)
Introduction
A stable pre-corneal tear film is essential to create a protective and lubricated environment for the tissues of the palpebral and bulbar surfaces and to provide the primary refracting surface for light entering the visual system [1]. Impaired tear film stability is one of the fundamental diagnostic criteria for diagnosing a loss of homeostasis of the tear film in dry eye disease and many ways of evaluating tear film stability have been described [2]. Tear film stability can be evaluated invasively by fluorescein breakup time (BUT) and non-invasively by projecting a grid or other pattern onto the tear film (NIBUT). The time interval following a complete blink to the first occurrence of breaks or a change in the reflected grid image is defined as the breakup time [3]. While the values of BUT are dependent on the amount, concentration, pH, drop size, presence of preservatives and the type of fluorescein used, the NIBUT method eliminates the physical disturbance of the tear film [[4], [5], [6]]. Furthermore, BUT can be affected by uneven tear mixing, illumination techniques and by inducing reflex tearing [5,[7], [8], [9], [10]]. Depending on the quantity of instilled fluorescein, the BUT cut-off values for dry eye have been reported to be ≤5 s for micro-quantities and ≤10 s for larger quantities of fluorescein [[11], [12], [13]].
NIBUT is recommended by the Dry Eye Workshop (DEWS ll), with a cut off of ≥10 s for normal values, using subjective methods [2]. Recently two new handheld instruments, similar to the well established, but no longer commercially available Keeler Tearscope Plus (Keeler Ltd, Windsor, UK) and video topographers equipped with additional software for objective analysis of placido ring distortion, have been launched [14].
Consequently, the aim of this multicentre study was to investigate the agreement of four different instruments in the measurement of non-invasive tear film breakup time (NIBUT) and to propose guidelines for applying the measurements to the diagnosis of dry eye disease.
Section snippets
Participants
Seventy-two participants (twenty-four per site) with a mean age of 24.2 ± 3.6 (SD) years (54 females) were recruited at three test sites at Aston University, Birmingham, UK; School of Optometry (HFAK) Cologne, Germany and University of Applied Sciences (FHNW), Olten, Switzerland. 37 participants were largely asymptomatic (OSDI < 13), 17 had mild (OSDI 13-22), 16 had moderate (OSDI 23-32) and 2 participants had severe symptoms (OSDI ≥ 33). A range of symptomology was required to assess the
Results
The descriptive data are summarised in Table 1 (median and ranges for NIBUT and OSDI), as well as in Fig. 2 (Boxplots for NIBUT median values). The Bland-Altman plots of the difference compared to the mean for each individual with each instrument combination are shown in Fig. 3. The objective Keratograph measures were on average (1.2 s ± 9.6 s 95 % confidence interval) greater than the subjective evaluations of NIBUT with the other instruments (mean difference 0.4 s ± 7.7 s 95 % confidence
Discussion
This prospective multicentre study reports on the use of four different devices to measure non-invasive tear breakup time (NIBUT). All of these instruments use the projection of a ring grid pattern to visualise the break-up of the tear film. The comparison of the handheld or slit-lamp mounted instruments (Tearscope Plus, Easytear, and Polaris) for subjective evaluation of NIBUT showed no significant difference between the NIBUT measurements. The NIBUT measurements (without cut-off of 24 s) for
Conclusions
NIBUT data of this study suggests that the four instruments for tear stability measurement give reasonably repeatable values that can be used interchangeably as long as objective instrument cut-offs are applied.
Declaration of Competing Interest
None.
References (27)
- et al.
TFOS DEWS II tear film report
Ocul Surf
(2017) - et al.
TFOS DEWS II diagnostic methodology report
Ocul Surf
(2017) - et al.
Clinical evaluation of the oculus keratograph
Cont Lens Anterior Eye
(2012) Desiccation of the precorneal film. I. Corneal wetting-time
Acta Ophthalmol (Copenh)
(1969)- et al.
Comparison of non-invasive tear film stability measurement techniques
Clin Exp Optom
(2018) - et al.
The effect of instilled fluorescein solution volume on the values and repeatability of TBUT measurements
Cornea
(2005) - et al.
A non-invasive instrument for clinical assessment of the pre-corneal tear film stability
Curr Eye Res
(1985) - et al.
Effect of fluorescein instillation on the pre-corneal tear film stability
Curr Eye Res
(1985) - et al.
The tear film: structure, function and clinical examination
(2002) - et al.
Interpretation of tear film breakup
Arch Ophthalmol
(1977)
Reliability of the tear break-up time technique of assessing tear stability and the locations of the tear break-up in Hong Kong Chinese
Optom Vis Sci
Alternative reference values for tear film break up time in normal and dry eye populations
Adv Exp Med Biol
Effects of fluorescein on tear breakup time and on tear thinning time
Am J Optom Physiol Opt
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Diagnostic accuracy of non-invasive tear film break-up time assessed by the simple manual interferometric device
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2021, Contact Lens and Anterior EyeCitation Excerpt :A cold light source usually refers to a light external to a microscope that allows diffuse illumination without marked thermal impact on the sample. It can be used to observe the stability of the tear film (usually in the form of a placido pattern), the tear meniscus and the lipid thickness (through interferometric patterns) [197]. Instruments can be used as stand-alone, some with digital imaging and objective software analysis [198], or in conjunction with a slit lamp biomicroscope for control and magnification.