Diagnostic ability of the breakup time measurements in detecting dry eye disease

INTERVENTION: In this investigator‐masked randomised crossover study, the tear film breakup time of participants will be assessed in triplicate, with and without sodium fluorescein instillation, in a randomised order, by two independent observers. A 30‐minute interval between measurements will ensure subsidence of reflex tearing. In the intervention arm, sodium fluorescein was applied to the bulbar conjunctiva from a fluorescein impregnated strip (Haag‐Streit) wetted with 1 drop (10‐20µl) of saline and shaken to remove excess fluid. Following fluorescein instillation, participants were then instructed to blink naturally over a 1 minute period to facilitate even distribution over the ocular surface. Tear film breakup time was then assessed in triplicate under blue light with a Wratten yellow filter. CONDITION: Dry eye disease PRIMARY OUTCOME: Fluorescein breakup time measured under blue light with a Wratten yellow filter. Non‐invasive tear film breakup time measured using automated Keratograph 5M readings (Oculus, Wetzlar, Germany). SECONDARY OUTCOME: Discriminative ability (area under receiver operator characteristic curve) and diagnostic accuracy (Youden optimal cut‐off sensitivity and specificity) of fluorescein and non‐invasive tear film breakup time in detecting dry eye disease (Ocular Surface Disease Index score greater than or equal to 13). INCLUSION CRITERIA: Participants will be enrolled into two age and gender matched groups, with and without symptomatic dry eye (Ocular Surface.Disease Index score greater than or equal to 13). Age of 18 years or older No history of major systemic disease. No history of ocular surgery. No use of topical or systemic medications known to affect the eye. Able to provide written informed consent