Vision of the Humboldt penguin (Spheniscus humboldti) in air and water.

Refractive states measured by retinoscopy and photorefraction indicate that the eyes of the Humboldt penguin, Spheniscus humboldti, are approximately emmetropic in air and water. Extensive myopia in air, as predicted by earlier authors and by a recent anatomical study, is non-existent. Photorefractive measurements of the refractive state, in water, of the Humboldt penguin indicate that it can accommodate sufficiently to make up the loss of the refractive power of the cornea. The cornea of the Humboldt penguin is flattened relative to the overall size of the eye. In all these respects (corneal flattening, and accommodation in air and water) the eyes of Humboldt penguins are like those of gentoo, (Pygoscelis papua), rockhopper (Eudyptes crestatus), Magellanic (Spheniscus magellanicus), and king penguins (Aptenodytes patagonica).