Alfaxalone-Based Anesthetic Combinations to Minimize Anesthesia-Induced Transient Lens Opacity in Rats (Rattus...

Anesthesia-induced lens opacity has been reported in rats and mice and is characterized as acute and reversible. In ophthalmologic research, lens opacity often interferes with the accurate acquisition of ocular data. In this study, we investigated the usefulness of alfaxalone, an anesthetic known for its favorable safety profile, for prevention of anesthesia-induced lens opacity in rats. First, anesthetic protocols using alfaxalone were screened to identify those suitable for the study. Then, the induction profiles of transient lens opacity following intraperitoneal administration of alfaxalone-butorphanol and alfaxalone-midazolam-butorphanol were evaluated, and the findings were compared with those obtained for ketamine-xylazine, which is known to induce lens opacity. Lens opacity induced by alfaxalone-based anesthetic combinations was significantly milder than that induced by ketamine-xylazine. Alfaxalone-based anesthetic combinations suppressed reflex responses, and alfaxalone-midazolam-butorphanol provided sufficient depth and duration of anesthesia for morphology-based assessment of the eye, although the depth of anesthesia was lower than that achieved with ketamine-xylazine. In conclusion, the combination of alfaxalone, midazolam, and butorphanol may represent a promising anesthetic option for ophthalmologic studies in rats.