Ophthalmic Diagnostic Tests and Ocular Findings in a Flock of Captive American Flamingos ( Phoenicopterus ruber ruber).

Abstract

Seventeen adult captive American flamingos ( Phoenicopterus ruber ruber) (34 eyes) underwent a complete ocular examination, including assessment of menace response, pupillary light reflexes, dazzle reflex, palpebral and corneal reflexes, fluorescein staining, slit-lamp biomicroscopy, and direct ophthalmoscopy. Birds were randomly assigned to one of 2 groups for tear production and intraocular pressure measurements. Tear production was measured by modified Schirmer tear test I (n = 9 birds) or phenol red thread test (n = 8 birds), and intraocular pressure was measured indirectly by applanation (Tonopen-XL) (n = 9 birds) or rebound (TonoVet) (n = 8 birds) tonometry. Conjunctival swab samples were taken from one randomly selected eye of all 17 birds to identify surface ocular microbial flora via aerobic bacterial culture. Additionally, 3 of the 17 birds were anesthetized for bilateral B-mode ocular ultrasonography examination to obtain axial globe measurements. Results showed that the menace response and dazzle reflex were absent in all birds. Sixteen of the 17 birds were free of significant ocular disease; a small cataract and pigment on the anterior lens capsule were noted in one eye of one bird. Mean ± SD tear production was 12.3 ± 4.5 mm/min (range, 4-20 mm/min) for modified Schirmer tear test I and 24.2 ± 4.4 mm/15 s (range, 14-30 mm/15 s) for phenol red thread test. Modified Schirmer tear test I measurements were significantly lower than phenol red thread measurements (P < .001). Mean intraocular pressure was 16.1 ± 4.2 mm Hg (range, 7-22 mm Hg) for Tonopen and 9.5 ± 1.7 mm Hg (range, 7-13 mm Hg) for TonoVet. Tonopen measurements were significantly higher than TonoVet measurements (P < .001). An Enterococcus species (9/17 eyes; 53%) and a gram-positive coccus (7/17 eyes; 41%) were the bacteria most commonly isolated from conjunctival swab samples. Mean B-mode ultrasonographic globe measurements of 6 eyes (3 birds) were axial globe length, 13.8 ± 0.16 mm; anterior chamber depth, 1.75 ± 0.05 mm; lens thickness, 4.6 ± 0.06 mm; vitreous body depth, 6.95 ± 0.10 mm; and pecten dimensions, 5.1 ± 0.38 mm length, 2.2 ± 0.14 mm width. In summary, the prevalence of ocular lesions was low in this population of captive American flamingos. Results obtained from 2 types of tear and intraocular pressure measurement tests were significantly different, indicating that a single type of each diagnostic test should be consistently used. A modification of the standard Schirmer tear test or use of phenol red thread test is recommended due to the small flamingo eye.