Tmbut Case Studies

At the beginning of this case study, a woman in her forties presented with symptoms of dry eye alongside numerous dysfunctions in her right side facial movement and sensation. The dry eye symptoms were causing her discomfort and the facial dysfunction consisted of an extended time between blinks, incomplete right eye closure, forehead smoothing and drooping of her mouth. When evaluating this patient’s symptoms, it seems that the problems relating to dry eye are very likely secondary to the facial dysfunction that is visibly apparent. Specifically the fact that the patient has reduced blinking activity and is suffering from lagophthalmos, incomplete eyelid closure, would lead to a deterioration and lack of replenishment of the tear film layer

To test the tear film integrity, fluorescein dye is applied to the temporal bulbar conjunctiva and the patient is instructed to blink several times to distribute the dye across the surface of the eye. Once the dye is spread, it is observed under a cobalt blue light allowing the dye to be clearly seen. A timer is run as the dye is observed and the examiner notes when the full thickness of the tear layer is seen to have evaporated . A normal, healthy result of a TBUT test will generally be ten seconds or more. A break up time between five and ten seconds could possibly indicate a problem and a time that is less than five seconds is highly indicative of issues such as dry eye . Since this patient’s result was only six seconds, it agrees with the reported symptoms of dry eye. One technique to note when administering TBUT tests is the application of the fluorescein dye. It is particularly important to apply the dye to the bulbar conjunctiva and to avoid any contact with the cornea. This is due to the sensitivity of the nerves in the corneal area . Any stimulation of these nerves instigates a high amount of reflexive tearing. Clearly if a practitioner is trying to evaluate the tear film, the results would not be reliable if the cornea was contacted and tear production suddenly increased. In addition to tear break-up time, fluorescein is useful in evaluating the