2018-03-01, Nosch, Daniela, Pult, Heiko, Albon, Julie, Purslow, Christine, Murphy, Paul J

Aim of this study - to determine: (A) the stimulus temperature inducing no or least change in ocular surface temperature (OST), using the Belmonte Ocular Pain Meter (OPM); and (B) to evaluate if OST remains unchanged with different stimulus durations and airflow rates. A total of 14 subjects (mean age 25.14 ± 2.18 years) participated: (A) OST was recorded using an infrared camera (FLIR A310) during the presentation of airflow stimuli, at five temperatures, ambient temperature (AT) +5°C, +10°C, +15°C, +20°C and +30°C, using the OPM; and (B) OST measurements were repeated with two stimulus temperatures (AT +10°C and +15°C) while varying stimulus durations and airflow rates. Results: (A) Stimulus temperatures of AT +10°C and +15°C induced the least changes in OST (-0.20 ± 0.13°C and 0.08 ± 0.05°C). (B) OST changes were statistically significant with both stimulus temperatures and increased with increasing airflow rates (p < 0.001).

2016-05-17, Nosch, Daniela, Pult, Heiko, Albon, Julie, Purslow, Christine, Murphy, Paul J

Purpose. To examine the possible role of corneal sensitivity and tear film quality in triggering a blink by investigating the relationship between blink rate, central corneal sensitivity threshold (CST), ocular surface temperature (OST), tear meniscus height (TMH), tear film quality (noninvasive tear break-up time [NIBUT]), and tear film lipid pattern under normal conditions. Methods. Fortytwo volunteers (average age 27.76+/-5.36 years; 11males) with good ocular health( OcularSurfaceDisease Index, <15.0) were recruited for this cross-sectional cohort study. Blink rate, CST (noncontact corneal air gas aesthesiometry, NCCA), minimum and maximum OST in the central and inferior cornea between blinks (thermal infrared camera), TMH, NIBUT, and lipid pattern of the tear film (Keeler Tearscope Plus) were recorded on the right eye only. Results. Median blink ratewas 11blinks/min (interquartilerange [IR], 6.95 to 17.05), CST was 0.35mbars (IR,0.30to0.40), minimum OST in the central cornea was 35.15°C (IR, 34.58 to 35.50), and NIBUT was 34.55 s (IR, 12.45 to 53.80). Moderate but statistically significant correlations were observed between CST and NIBUT (r = 0.535, p < 0.001), CST and blink rate (r = -0.398, p < 0.001), lipid pattern and OST (r = 0.556, p < 0.001), and between CST and OST (r = 0.371, p = 0.008). The correlations between blink rate and NIBUT (r = -0.696, p < 0.001) and between OST and NIBUT (r = 0.639, p G 0.001; Spearman test) achieved higher significance; this was highlighted by the linear regression model where NIBUT and minimum central and inferior OST were identified as significant predictor variables. Conclusions. There is strong evidence for significant interactions between corneal sensitivity, NIBUT, OST, and blink frequency, emphasizing that ocular surface conditions represent a possible important trigger for the initiation of a blink. However, the mechanisms involved in the initiation of a blink are complex, with local ocular sensory input as only one trigger, along with other external influences and internal factors under cortical control.