Effect of local hypothermia on the anterior chamber and vitreous cavity temperature: in vivo study in rabbits

BACKGROUND: This study aims to record the variations of the anterior chamber and vitreous cavity temperature after application of local hypothermia. MATERIAL AND METHODS: Local hypothermia was applied on 20 rabbits' eyes after general anesthesia using a liquid which had been placed in a special plastic container and had been frozen at -20 degrees C. In 10 rabbits (Group A) the frozen container was placed on the eyes without direct contact with the cornea, the hypothermia being applied through the eyelids, for 10 min. In the other 10 rabbits (Group B), the container was in direct contact with the cornea for 10 min. After that time, both the anterior chamber and vitreous cavity temperatures were measured in both groups using a special 20 G tip and were recorded with a digital thermometer (BAT-10, Physitemp Instruments Inc.). Reactions on the fundus were assessed by indirect ophthalmoscopy one day after hypothermia application. RESULTS: Mean reduction from the body temperature of temperature in the anterior chamber and in the vitreous was 10 +/- 1 degrees C and 4.2 +/- 0.5 degrees C respectively for Group A, and 20 +/- 0.8 degrees C and 8.5 +/- 0.5 degrees C respectively for Group B. All differences were statistically significant. CONCLUSIONS: Our study shows that local hypothermia application, even without direct contact with the cornea, reduces significantly the temperature in the center of the vitreous in rabbits. This temperature reduction could be beneficial in conditions of intraocular inflammation, where hypothermia could act synergetically with other means to decrease the anterior and/or posterior segment inflammation.