Accuracy and sensitivity of the dynamic ocular thermography and inter-subjects ocular surface temperature (OST) in Chinese young adults

Abstract 

Purpose

To investigate the accuracy and sensitivity of the Thermo-Tracer TH9100MV, NEC San-ei in monitoring the temperature of the anterior eye surface and to establish an inter-subjects ocular surface temperature (OST) norm in Chinese young adults.

Methods

A blackbody with fixed temperature was used to study accuracy and sensitivity of the thermal camera used (Thermo-Tracer TH9100MV, NEC San-ei). Sixty healthy Chinese young adults aged 17–21 (mean age 19) were recruited from the Singapore Polytechnic Optometry Centre. A room with standard room temperature and humidity was used. Subjects were adapted to the room conditions for 20min before measurement. OST was then measured within 4–5s after a blink and with their upper lid lifted by a cotton bud, using infrared thermo-camera, in a non-invasive manner.

Results

All future Thermo-Tracer readings could be converted to ‘true’ temperature via the regression equation derived y=1.0884x−3.4026 (r²=0.9985), where y is the ‘true’ temperature and x is reading by Thermo-Tracer. Sensitivity of the machine for all 16 temperatures studied was found to be 91.3%. Mean OST for the population studied was 34.70±0.50°C. Mean OST at geometrical centre cornea (GCC) was 34.39±0.47°C and inter-ocular temperature difference was ∼0.20±0.15°C. Both the horizontal and vertical OST profile was established. No significant differences between right/left eyes and between genders were found at 95% CI.

Conclusions

Findings on the accuracy can be used as a reference by researchers who are using the same infrared thermal camera. It is proven that the machine has high sensitivity in determining the temperature of anterior ocular surface. Methodology used in this study can also be applied to the determination of the accuracy and sensitivity of the dynamic range for other infrared thermal cameras. Inter-subjects OST norm in Chinese young adults aged 17–21 was established.

Keywords: Dynamic thermography, Ocular surface temperature, Blackbody, Geometric centre of the cornea, Infrared thermal camera