Ocular surface heat effects on ocular hemodynamics detected by real-time measuring device

To investigate the ocular hemodynamic effects of applying a hot compress to the eye.

The right eyes of five New Zealand white rabbits, both male and female, were hot-compressed for 18min. An independently designed novel ocular contact-type temperature measuring device was used to measure the ocular surface temperature before and after the heating. Relevant retrobulbar hemodynamic parameters such as peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) of each of the central retinal artery (CRA), long posterior ciliary artery (LPCA), and ophthalmic artery (OA), as well as the mean velocity (V_m) of the central retinal vein (CRV), were measured using a color Doppler flow imaging (CDFI) technique and expressed as mean values with standard deviation (mean±SD). A statistical analysis was conducted based on a paired t-test and the Wilcoxon signed-rank test.

The employed real-time temperature measuring device was able to accurately measure ocular surface temperature during the hot-compress process. The temperature increased after the hot compress was applied. Analysis showed that the PSV and EDV values of the CRA and LPCA significantly increased after the application of the hot compress, as did the V_m of the CRV. There were no significant changes in the EDV of the OA nor the RI of each artery.

This experiment, which is the first of its kind, confirms that the retrobulbar blood flow velocities can increase upon heating the ocular surface. This simple method may be useful in the future.