Abstract
Purpose :
This pilot study deals with methodological aspects of dynamic ocular tomography and contributes to better understanding and more effective management of eye diseases. The issues addressed in the study include: (a) technical requirements to a measurement setup; (b) repeatability and variability; (c) the impact of the chosen region of interest’s size and shape; (d) pilot data concerning gender-, age- and disease-related peculiarities.
Methods :
The study group comprised in total 109 volunteers (47 presumably healthy subjects and 62 subjects having different systemic and eye diseases) ranging in age between 18 and 88 years (66 F and 43 M). Ocular surface temperature was measured at sampling rate 10 Hz during 6 sec using the VarioCAM HD camera (InfraTec GmbH, Germany), equipped with uncooled microbolometer (320 x 240; 0.01°C). The camera was adjusted to face the geometric center of the cornea (20 cm from the eye). Software packages IRBIS® 3.1 plus and LabVIEW® were used for data acquisition and analysis.
Results :
The ocular surface temperature measured directly after blinking, displayed exponential time course T(t)=exp(-µt). Just like in the static ocular thermography, specific regions of interest (ROIs) can be assigned for better surface cooling comparisons. Collation of the static mean surface temperatures “mean ± SD” obtained using elliptic (T=34.34±0.02°C) and line-shaped (T=34.35±0.03°C;) ROIs revealed essentially no differences (p=0.08). Nevertheless, the ocular surface cooling rates (OSCR) measured as temperature drop dT within four seconds, differed significantly (elliptic ROI: dT=0.10±0.05°C; line-shaped ROI: dT = 0,08±0.62°C; p<0.001). Higher cooling rates were measured in the female group (dT=0.44±0.22°C) as compared to the male group (dT=0.33±0.21°C; p < 0,007). Preliminary comparison of OSCR values from healthy individuals (n=47) with those obtained from glaucoma patients (n=13) implies lower cooling rates for the eyes with glaucoma (dT=0,26±0.17°C) vs. non-glaucomatous eyes (0.47 ±0.23°C, p<0.01). A weak trend of aged patients to display higher cooling rates was observed as well.
Conclusions :
The dynamic ocular thermography allowed us detecting differences and correlations not visible upon using the conventional static methods which makes the technique worthy of further development.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.