|Title||THE ASSOCIATION BETWEEN OCULAR SURFACE SENSORY RESPONSES AND TEAR FILM INSTABILITY|
|Author, Co-Author||Jun Zhang, Ping Situ, Carolyn Begley, Trefford Simpson|
Tear film instability (TFI) is a core mechanism of dry eye (DEWS, 2007), but the sensory response of the ocular surface to TFI is not fully understood. In this study, we investigate the relationship between TFI and the ocular surface sensory response during and after repeated prolonged eye opening.
Ten subjects were seated behind a slit lamp biomicroscope and were asked to keep one eye open as long as possible (maximum blink interval=MBI) while fluorescein TFI was monitored and subjects simultaneously indicated the level of discomfort using a “discomfort knob” (DK) potentiometer (0-10 scale). The MBI procedure was repeated 10 times. Discomfort and burning sensations during and after each trial were rated using 0-10 visual analogue scales (VAS). The Dry Eye Questionnaire (DEQ) was filled out before and the Current Symptom Questionnaire (CSQ) was filled out before and after the study procedures. Video frames at the time of DK increase were extracted and a custom MATLAB program was used to quantify the area of tear break-up (TBU) over the cornea. The Pearson correlation coefficient was used to determine the association between TBU area and sensory responses.
The average TBU area over 10 trials was significantly correlated to the discomfort and burning sensation subjects reported after prolonged eye opening (r=0.70 and 0.73 for discomfort and burning, respectively, both p<0.05). There were significant correlations between sensations of burning and discomfort during and after prolonged eye opening (r=0.70, p<0.05 and 0.98, p<0.01 for during and after, respectively). An inverse correlation was found between DK slope (DK/time) and MBI (r=-0.72, p<0.05). DEQ-5 scores were significantly correlated to CSQ scores before the experiment and burning sensation during eye opening (r=0.85, p<0.01 for CSQ scores and 0.65, p<0.05 for burning sensation).
Discomfort and burning sensations after prolonged eye opening are related to the amount of TBU, suggesting that TFI produces nociceptive stimulation to the ocular surface.
The project described was supported by Grant Number R01EY021794 from the National Eye Institute.
|Affiliation of Co-Authors||University of Waterloo, School of Optometry and Vision Science|