Temperature gradients in the rabbit eye.

Measurements of the temperature of the various parts of the rabbit eye under both local and general Nembutal anesthesia were made ivith the thermistor as the temperature-measuring device at a room temperature of 22 to 24° C, and a relative humidity of 33 to 53 per cent. The equipment and its calibration are described in detail. The existence of a temperature difference of 6° C. (corrected for the depressant effect of Nembutal anesthesia on rectal temperature) was shown to exist between the orbit and the central corneal surface along the pupillary axis. No significant difference was noted between right and left eyes except for the central corneal surface temperature under local Ophthaine anesthesia, when the temperature of the left eye was found to be higher than that of the right by 0.5° C. An estimation of the temperature gradients indicates that at the mid-lens position the gradient increases sharply toward the corneal surface. Some of the possible physiologic effects of the ocular temperature gradient are discussed, such as the choice of temperature for study of the metabolism of ocular tissues in vitro, the role of the temperature gradient in the maintenance of the intraocular pressure on the basis of the irreversible thermodynamic approach, and its role in the transfer of fluid across the cornea.