September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Effects of experimental tear film instability on sensory responses to corneal cold, mechanical and chemical stimuli
Author Affiliations & Notes
  • Ping Situ
    School of Optometry, Indiana University Bloomington, Bloomington, Indiana, United States
  • Trefford L Simpson
    School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
  • Carolyn G Begley
    School of Optometry, Indiana University Bloomington, Bloomington, Indiana, United States
  • Footnotes
    Commercial Relationships   Ping Situ, None; Trefford Simpson, None; Carolyn Begley, None
  • Footnotes
    Support  NIH Grant R01EY021794 (Dr. Begley)
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 2849. doi:
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      Ping Situ, Trefford L Simpson, Carolyn G Begley; Effects of experimental tear film instability on sensory responses to corneal cold, mechanical and chemical stimuli. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2849.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To investigate the effect of experimental tear film instability (TFI) induced by repeatedly holding the eyes open, on sensory responses to corneal cold, mechanical and chemical stimuli.

Methods : Fifteen non-contact lens wearing normal subjects (7 females and 8 males) participated. The pneumatic cold, mechanical and chemical stimuli were delivered using a computer-controlled Belmonte ethesiometer on three separate visits. TFI was induced during 10 repeated trials of sustained eye opening (BSP). The magnitude of the sensory responses to threshold and suprathreshold (1.25 and 1.5 times of threshold) stimuli were assessed for stimulus intensity, coolness or warmness, irritation and pain, using a 1 (very mild) to 100 (very strong) scale, prior to and following BSP stimulation. In addition, symptoms of ocular discomfort were evaluated using the Current Symptoms Questionnaire (CSQ). Repeated measures ANOVA was used for data analysis.

Results : Before BSP, the mean (±SEM) cooling, mechanical and chemical thresholds were 59.2 ± 4.7 ml/min, 72.7 ± 6.0 ml/min, and 26 ± 1.8 %CO2, respectively. Stimulus intensity ratings significantly increased for all three types of suprathreshold stimuli (all p≤0.001). The attribute ratings of coolness (to room-temperature stimuli) and irritation (to mechanical and chemical stimuli) increased to suprathreshold stimuli (all p≤0.008). Following BSP, the intensity and coolness ratings to cooling stimuli decreased (p=0.043 and 0.044 for intensity and coolness, respectively), while irritation rating to mechanical stimuli was increased (p=0.024). As in previous studies (Begley et al, 2006), the CSQ scores increased following BSP stimulation regardless of visits (all p<0.001).

Conclusions : Repeated TFI induced by BSP leads to an increase in symptoms of ocular discomfort, accompanied by perceived changes in the attributes of sensation (reduced coolness of cooling, and increased irritation of mechanical pneumatic stimuli). The decrease in cooling and increase in irritation after BSP suggest a complex interaction of neural mechanisms giving rise to ocular surface sensation in humans.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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