intraocular pressure determination in clinically normal redfooted tortoise geochelone carbonaria intraocular pressure iop reflects a balance between aqueous humor production and outflow and is often an essential ophthalmic diagnostic procedure in animals the objective of this study was to estimate iop in clinically normal redfooted tortoises geochelone carbonaria of various sizes by using applanation tonometry intraocular pressures were estimated for 25 captive redfooted tortoises 10 males 10 females and 5 animals of unknown sex by using an applanation tonometer after topical anesthesia body length ranged from 51 to 549 cm measured from nuchal to anal scutes five measurements from each eye were obtained by a single observer in an ambient temperature of approximately 30 degrees c observers reliability was good intraclass r 075 and iop did not change over the ordered sequence of five replicate measurements for individual tortoises the correlation for iop between the left and right eyes was low r 020 the paired ttest did not show any statistical effect p 0426 for the difference in iop between the left and right eyes mean iop determined for 10 confirmed males and 10 confirmed females did not differ between sexes p 0244 the mean iop of five small tortoises 10 cm long in redfooted tortoises there does not appear to be any relation between carapace length and iop