Refractive state, ocular anatomy, and accommodative range of the sea otter (Enhydra lutris)

Christopher J Murphy, Roy W. Bellhorn, Tom Williams, Margaret S. Burns, Frank Schaeffel, Howard C. Howland

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Sea otters are carnivorous, amphibious mammals that are active both above and under water. Accordingly, it might be expected that their eyes are adapted for both aerial and aqueous vision. We examined the anatomy and physiological optics of the sea otter eye with a view towards describing and explaining its amphibious visual characteristics. We employed photokeratoscopy to measure the refractive power of the sea otter cornea, which we found to be 59 D. Using video dynamic photorefraction, we found that sea otters can focus targets clearly both in air and water, relying on accommodation to compensate for the refractive loss of their corneas upon immersion in water. Our anatomical investigations revealed that the anterior epithelium of the cornea is extensively developed, as is the iris musculature, meridional ciliary muscle, and the corneoscleral venous plexus. The first feature is most likely an adaptation to the salinity of the marine environment. We believe the latter features are part of a novel, well-developed lenticular accommodative mechanism.

Original languageEnglish (US)
Pages (from-to)23-32
Number of pages10
JournalVision Research
Volume30
Issue number1
DOIs
StatePublished - 1990

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Keywords

  • Accommodation
  • Corneal curvature
  • Enhydra lutris
  • Optics
  • Photokeratometry
  • Photorefraction
  • Refraction
  • Sea otter

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

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