2. Non-Invasive Keratograph Tear Break-Up Time versus Invasive Fluorescein-Associated Tear Stability Test: Experimental Validation Study
Nizar S Abdelfattah, M.D., SriniVas R Sadda, M.D., Olivia L Lee, M.D.
Doheny Image Reading Center, Doheny Eye Institute and the Department of Ophthalmology,
David Geffen School of Medicine at UCLA, Los Angeles, CA
Financial Disclosures
Dr. Lee
Dr. Sadda
Dr. Abdelfattah
Consultant: Allergan
Research Grant Support: Allergan
Consultant: Allergan, Genentech, Regeneron, Optos, Carl Zeiss Meditec
Research Grant Support: Optos, Carl Zeiss Meditec, Allergan, Genentech
None

3. Purpose
To test the validity of the automated noninvasive tear break-up time (NIKBUT) measurement tool offered by the Oculus Keratograph 5M.

4. Patients & Methods
Seventy participants (94 eyes) were recruited prospectively over 9 months and divided into two groups.
The ocular surface diseases (OSD) group included 63 eyes (74% females, 63.5 ± 14.6 years) diagnosed clinically with dry eye and/or Meibomian gland dysfunction.
The control group included 31 eyes of healthy volunteers (53 % females, 34.8 ± 10.5 years).

5. Methods
All eyes were imaged non-invasively with the Oculus K5M (Wetzlar, Germany) using the NIKBUT tool.
Based on infrared imaging of the tear film over the corneal surface, automated analysis of first break up time (NIKBUT-F) and average value for break up times (NIKBUT-A) was performed by the instrument’s software.
Manual assessment of tear break up (NIKBUT-M) was also analyzed, guided by distortion of the Oculus mires reflection on tear film.
For comparison, fluorescein was used to stain the tear film and tear break-up time (TBUT) was manually graded based on videos captured on the Oculus K5M using cobalt blue light.
All subjects completed the Ocular Surface Disease Index (OSDI) survey.

6. Results Before Break up I. First Breakup Time (NIKBUT-F):
This represents the time at which the first breakup of tears takes place.
After Break up
II. Average Breakup Time (NIKBUT-A):
This represents the average time at which the all breakup fields of tears take place during period of video recording.
III. Manual Breakup Time (NIKBUT-M):
This represents the time at which device mires undergo fixed distortion. This method is not offered automatically by the device but manually determined by the gradrer.

7. Results
As expected, strong negative correlation was detected between standard TBUT and OSDI score (r = 0.8, p < 0.001).
Poor correlation was detected between all NIKBUT readings and OSDI survey scores (r = 0.8, p < 0.05)
Poor correlation was found between non-invasive measurements (NIKBUT-F & NIKBUT-A) and standard fluorescein TBUT (r = 0.17, p < 0.1 and r = 0.14, p < 0.01 respectively).

8. Results
P = 0.54
P = 0.73
There is no statistically significant difference between NIKBUT readings in eyes with MGD vs. controls.

9. And strong negative correlation between OSDI and TBUT.
Results
R = 0.70
P < 0.05
There is a statistically significant difference between TBUT readings in eyes with MGD vs. controls.
And strong negative correlation between OSDI and TBUT.

10. Results

11. Results
Statistically significant strong positive correlation was appreciated between:
NIKBUT-F and NIKBUT-M (r = 0.8, p < 0.05)
NIKBUT-F and NIKBUT-A (r = 0.63, p < 0.01)
NIKBUT-A and NIKBUT-M (r = 0.74, p < 0.05)

12. Conclusions
The Oculus Keratograph 5M is able to provide automated tear break up time values without the use of fluorescein and cobalt blue light.
However, the automated NIKBUT values are not strongly correlated to either standard fluorescein TBUT or the OSDI questionnaire.
The automated measurements of tear break up time do not demonstrate statistically significant differences between ocular surface disease and normal controls, while the traditional fluorescein method does.
Nevertheless, the presence of a correlative pattern among NIKBUT subtypes suggests a potential differentiating trait amongst ocular surface disease states that can be further explored.