Abstract

Ophthalmic examinations were performed on 160 macaroni penguins (Eudyptes chrysolophus) and 90 rockhopper penguins (Eudyptes chrysocome) at eight North American zoological institutions. Cataract prevalence was 46.5% (n=74) in the macaroni population and 45.5% (n=40) in the rockhopper population. Macaroni penguin eyes with cataracts had significantly lower intraocular pressure (IOP) than eyes without cataracts (p=0.001): 36.4±9.0 mm Hg (n=135) vs. 42.0±9.7 mm Hg (n=179). Rockhopper IOP did not differ significantly between eyes with and without cataracts (p=0.079): 31.2±6.4 mm Hg (n=73) vs. 32.9±6.2 mm Hg (n=101). Incipient and hypermature cataracts were the most prevalent in rockhopper and macaroni populations, respectively. Mean age of a macaroni and rockhopper with incipient cataracts was 13.1±6.9 yr and 21.0±5.6 yr, respectively. Husbandry, heredity, exhibit light intensity, and ultraviolet light measurements were evaluated as potential risk factors for cataracts. Major risk factors for macaroni penguins included age, smelt in diet, hand-feeding, increasing density of Eudyptes penguins, and fluorescent lighting. Major risk factors for rockhopper penguins included age, capelin in diet, increasing density of Eudyptes penguins, increasing minimum photoperiod, and decreasing light intensity. Protective factors for macaroni penguins included saltwater pools, water quality monitoring, pool filtration and sterilization systems, use of metal halide lights, increasing light intensity, and increasing UV light. Protective factors for rockhoppers included herring in diet, increasing terrestrial area, increasing maximum photoperiod, increasing light intensity, and increasing UV light.

Acknowledgments

Funding for this study was generously provided by the Aline Underhill Orten Foundation.