Monitoring of rabbit cornea response to dehydration stress by optical coherence tomography.

PURPOSE To evaluate the application of optical coherence tomography (OCT) for continuous noninvasive monitoring and quantification of the dynamics of corneal response after exposure of the cornea to dehydrating stress. METHODS The changes in central corneal thickness (CCT) and scattering properties of the cornea were monitored with OCT in rabbit cornea in vivo after topical application of a glycerin-based hypertonic agent (HA) or prolonged surface evaporation of the cornea. The observed changes in backscatter were correlated with the changes in corneal hydration. RESULTS An inverse relationship was found between the logarithm of the intensity of backscatter within the cornea and the degree of corneal hydration at which the intensity of the backscatter changed up to 20 times between the peak of the de- and rehydration phases. An analytical relationship is derived between the magnitude of the backscatter from the stroma and the extent of corneal hydration. Furthermore, depending on the concentration of the drug, a peak overshoot in corneal thickness in the range of 40% to 90% was detected during the rehydration process after topical application of the HA. At a 100% concentration of HA, the average dehydration rate was 74 microm/min, whereas the average rehydration rate was 12.4 microm/min. The same parameters for surface evaporation were 2.7 and 1.5 microm/min, respectively. CONCLUSIONS OCT may offer a unique capability to quantitatively monitor the dynamics of corneal response and to assess corneal function based on noninvasive detection of the changes in the optical properties and morphology of the cornea after topical application of dehydrating agents.