Analysis of the Mechanism of the Delay Characteristics in Cornea Deformation for Non-contact Tonometry

Through the observation of the eye deformation during an air jet application, we found that the eye deformation is always delayed with respect to the starting time of the air jet application. In order to explain such a characteristic, we newly introduce the cornea chain model, which assumes that the surface can be bent without any resistance under zero internal pressure, while it can not be deformed under an adequate internal pressure. We show that the chain model can nicely explain the characteristic distribution in the cornea deformation. Furthermore, we show that a pretty high correlation (R=0.816) exists between the delay time and the estimated internal eye pressure. This result can be used in a new type of a non-contact tonometer, which measures the internal eye pressure based on the delay time and which is gentler for eyes than the conventional one.