Perspiratio Insensibilis of the Cornea

Abstract

Introduction: The deswelling of the cornea via the natural pathways of perspiratio insensibilis and endothelial pump has been known for a long time. However, reliable data on the amount of perspiratio insensibilis, especially in edematous corneas, have been lacking until now. Material and Methods: In the Ex Vivo Eye Irritation Test (EVEIT), corneas can be observed purely physically under defined and stable biochemical conditions. The thickness and temperature of the corneas is measured by infrared thermography and Optical Coherence Tomography (OCT). Three corneas in stable MEM EVEIT culture and three corneas with induced and reversible edema in an EVEIT osmolar deficiency culture were placed in at 20°C and 60% humidity while tracking thickness and temperature for 30 minutes. Results: Over a period of 30 minutes, the temperature of both, healthy and edematous EVEIT corneas decreased from an initial 28°C to 21°C. The corneal thickness decreased by 51 ±12 μm in the healthy corneas and by 131 ±16 μm in the edematouscorneas. Conclusion: The considerable thickness differences between healthy and swollen corneas might give a physical and physiological explanation of some observable clinical effects in Fuchs’s endothelial dystrophy. The clinically observed effect of clearing of the cornea during the waking period. Furthermore, some phenomena of Dry Eye Syndrome (DES) can be explained by this difference of increased water release from the eye.