Ophthalmic examination findings in captive ring-tailed lemurs (Lemur catta, Linnaeus 1758)

Abstract

This study aimed to document normal ophthalmic findings and ocular anomalies in captive ring-tailed lemurs (Lemur catta) and to establish reference intervals for the Schirmer tear test-1 (STT) and intraocular pressure (IOP). Sixty healthy adult lemurs (22 females, 38 males) aged from 6 months to 28 years underwent ophthalmic examination. Direct illumination, STT, diffuse and slit-lamp biomicroscopy, fluorescein dye test, IOP measurement, and indirect ophthalmoscopy were performed on each eye. Reference intervals were calculated non-parametrically for STT and IOP. The eyes of three lemurs, which had died from unrelated reasons, were examined histopathologically. The median STT in the lemurs was 9 mm/minute, with an estimated 95% reference interval of 2–15 mm/minute. The median IOP was 18 mmHg, with an estimated 95% reference interval of 11–24 mm Hg. Ophthalmic abnormalities were noted in 21 of 120 (17.5%) eyes, including third eyelid laceration, corneal leukoma, cataracts, chronic uveitis, and vitreous degeneration. Reference intervals of physiological ophthalmic parameters and the most common ophthalmic findings are defined and can be useful for clinical veterinarians during the eye examinations of ring-tailed lemurs.