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Brief Report
March 2018

Comparative Evaluation of Clinical Methods of Tear Film Stability Assessment: A Randomized Crossover Trial

Author Affiliations
  • 1Department of Ophthalmology, New Zealand National Eye Centre, The University of Auckland, New Zealand
JAMA Ophthalmol. 2018;136(3):291-294. doi:10.1001/jamaophthalmol.2017.6489
Key Points

Question  How do tear film stability measurements obtained with an automated noninvasive keratograph corneal topographer compare with the conventional fluorescein method?

Findings  In an investigator-masked randomized crossover trial of 74 participants, fluorescein breakup time measurements were shorter and more narrowly distributed than those from automated noninvasive keratograph measurements. The keratograph had superior discriminative ability and diagnostic accuracy in detecting dry eye.

Meaning  The results suggest that the automated noninvasive technique may be a more sensitive method of measuring tear film stability for dry eye evaluation.


Importance  Tear film breakup time assessment is an integral component of dry eye evaluation. To our knowledge, the comparative discriminative ability of the noninvasive Keratograph (Oculus) vs conventional fluorescein method in detecting dry eye is unknown.

Objective  To compare tear film stability measurements obtained with an automated noninvasive corneal topographer vs conventional fluorescein methods and evaluate their respective discriminative ability in detecting dry eye.

Design, Setting, and Participants  This investigator-masked randomized crossover trial was conducted at a single-center university clinic between May 26, 2016, and October 3, 2016, and included 74 participants 18 years or older. Participants were recruited into 2 equally sized age, sex, and race/ethnicity–matched groups, with and without symptomatic dry eye (Ocular Surface Disease Index ≥13).

Interventions  Participants were assigned to receive a noninvasive keratograph evaluation and topical fluorescein instillation in a randomized order.

Main Outcomes and Measures  Noninvasive keratograph breakup time (NIKBUT) and fluorescein breakup time (TBUT). Area under the receiver operating characteristic curve, Youden-optimal diagnostic cutoff sensitivity, and specificity of NIKBUT and TBUT in detecting dry eye.

Results  Seventy-four participants (74 eyes; 43 women [58.1%]) with a mean (SD) age of 24 (4) years were randomized. Noninvasive keratograph breakup time was significantly longer than TBUT in participants with dry eye (median, 6.3 seconds vs 4.3 seconds [difference, 2.0 seconds]; 95% CI, 1.1-3.4 seconds; P = .003), and healthy participants (median, 11.9 seconds vs 5.0 seconds [difference, 6.9 seconds]; 95% CI, 4.7-7.6 seconds; P < .001). Fluorescein breakup time measurements were more narrowly distributed in both the dry eye (variance, 188 seconds2 vs 27.9 seconds2; P < .001) and control groups (variance, 113 seconds2 vs 13.4 seconds2; P < .001). The discriminative ability of NIKBUT in detecting dry eye (area under the receiver operating characteristic curve, 0.68; 95% CI, 0.56-0.81; P = .007) was greater than that of TBUT (area under the receiver operating characteristic curve, 0.57; 95% CI, 0.44-0.70; P = .31). The optimal diagnostic cutoff for NIKBUT was 9 seconds or less with a sensitivity of 68% (95% CI, 50%-82%), specificity of 70% (95% CI, 53%-84%), positive likelihood ratio of 2.27 (95% CI, 1.32-3.91), and negative likelihood ratio of 0.46 (95% CI, 0.28-0.77). The optimal threshold for TBUT was 5 seconds or less with a sensitivity of 54% (95% CI, 37%-71%), specificity of 68% (95% CI, 50%-82%), positive likelihood ratio of 1.67 (95% CI, 0.96-2.89), and negative likelihood ratio of 0.68 (95% CI, 0.45-1.03).

Conclusions and Relevance  Conventional fluorescein tear film breakup time measurements were significantly shorter with narrower distributions, while automated noninvasive keratograph readings displayed superior discriminative ability in detecting dry eye.

Trial Registration  anzctr.org.au Identifier: ACTRN12617001428358

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