Abstract
Purpose :
To study the changes in corneal surface temperature (CST) and tearing and blinking rates during ocular surface inflammation induced by exposure to ovalbumin in sensitized guinea pigs.
Methods :
Adult guinea pigs of both sexes were studied. Sensitization to ovalbumin (OVA) was induced by i.p. injection of 100µg OVA+20mg Al(OH)3 in 1ml PBS on day 0. On day 14th, 10 µl of 10% OVA were instilled into both eyes to produce the allergic challenge. Tearing rate and CST were measured before and 5 min after the allergic challenge. Tearing rate was measured using phenol red threads placed in the nasal canthus for 30 s, and was defined as the lenght of wet thread, in mm. To calculate blinking rate, the number of blinks during a 5 min-period were counted by two investigators. CST was measured using an infrared thermal camera (InfRec R300SR, Nippon Avionics) for continuous recording of infrared video images. The images obtained before and during the allergic challenge were analyzed using dedicated software. The CST value immediately after eye opening and the slope of the CST temperature decay during the interblink period (during 5s and 10s after the eye opening) were calculated.
Results :
Tearing rate increased significantly after the allergic challenge (25.2±3.4 mm vs 37.6±2.2 mm, before and after the allergic challenge; p<0.05, paired t-test). Blinking rate was also increased in allergic eyes (4.2±2.2 blinks/5min vs 9.3±5.4 blinks/5min). The initial CST immediately after eye opening was significantly increased during allergic inflammation (36.46±0.12°C vs 36.81±0.07°C, before and after the ocular allergic reaction; p<0.01, paired t-test), although the slope of the corneal temperature decrease during the interblink period, was only slightly higher after the allergic challenge (First 5s: -0.03±0.01°C vs -0.05±0.02°C, before and after the allergic challenge; p>0.05, paired t-test. First 10s: -0.02±0.01°C vs -0.03±0.004°C, before and after the allergic challenge; p>0.05, paired t-test.).
Conclusions :
The increase in tearing and blinking rates, and in corneal surface temperature during the ocular allergic reaction likely reflects the inflammation state. A faster corneal temperature decay by evaporation during the interblink period expected from the higher initial corneal surface temperature appears to be compensated by the increased tearing.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.