The effects of anesthesia and gender on intraocular pressure in lions (Panthera leo)

Intraocular pressure (IOP) was measured in a pride of 22 (11 males, 11 females) lions (Panthera leo) using a Schiotz tonometer. Two anesthetic protocols were used in the study. Lions in group I (n = 14) were anesthetized using xylazine, atropine sulfate, and ketamine. Lions in group II (n = 8) were anesthetized using ketamine and diazepam. Five sequential readings were taken from each eye of every lion. There were no significant differences in IOP between the two anesthetic groups, between left and right eyes, or over the five readings. The IOP was significantly higher in males than in females, controlling for age and weight. The mean (±SD) tonometer reading in 22 eyes of 11 male lions was 2.9 (±0.5) mm; with a 95% confidence interval (CI) of 1.6-4.5 mm. The mean tonometer reading in 22 eyes of II female lions was 4.0 (±0.7) mm, with a 95% CI of 1.8-6.3 mm. Using the 1955 Friedenwald human calibration table, the estimated mean IOP in 22 eyes of 11 male lions was 24.9 (±2.0) mm Hg, with a 95% CI of 20.4-29.4 mm Hg. The estimated mean IOP in 22 eyes of 11 female lions was 20.9 (±2.4) mm Hg, with a 95% CI of 15.6-26.3 mm Hg.