Normal Anatomy of the California Sea Lion globe
Normal Anatomy of the California Sea Lion globe
Normal Anatomy of the California Sea Lion globe
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Through <strong>the</strong> eyes <strong>of</strong> a sea lion<br />
Sarah Miller<br />
Richard Dubielzig, DVM, DACVP
The Globe<br />
Large Diameter<br />
Cornea thicker peripherally<br />
flattened cornea<br />
Due to stroma<br />
Shorter internal axial length<br />
more accurately defines optical function
The Cornea<br />
Flattened region over a stenopaic pupil<br />
not seen histologically
Bowman’s membrane<br />
TEM<br />
Descemet’s thin<br />
Endo<strong>the</strong>lium thin<br />
The cornea
Extensive constriction <strong>of</strong> pupil<br />
protects from large changes in<br />
illumination<br />
Iridocorneal angle<br />
Thick pectinate ligament with<br />
intermittent open channels<br />
Intermittent corneoscleral<br />
trabecular meshwork<br />
Anterior Uvea
Dilator muscle<br />
absent at <strong>the</strong> pupil<br />
Robust near iris base where it<br />
abutts sphincter m.<br />
Near pectinate ligament<br />
Extends over widened base <strong>of</strong><br />
ciliary processes<br />
Sphincter muscle<br />
Thickest near iris base<br />
Near pectinate ligament<br />
Accomodation??<br />
Anterior Uvea
Ciliary Body<br />
Dilator muscle extending up <strong>the</strong> base <strong>of</strong> <strong>the</strong> ciliary processes<br />
Circumferential smooth muscle subtending zonular ligaments<br />
accomodation??<br />
Lens attachment: direct attachment <strong>of</strong> ciliary processes<br />
zonular fibers
The Lens<br />
Spherical lens<br />
Heterogeneous (multifocal)<br />
Lower R.I. in periphery<br />
Compensates for <strong>the</strong> inability <strong>of</strong> <strong>the</strong> cornea to refract<br />
underwater<br />
Spherical lens<br />
http://lifestyle.iloveindia.com/lounge/images/facts-about-pinniped-2.jpg
Tapetum lucidum<br />
• Tapetum lucidum covers 2/3 to entire fundus
Tapetum lucidum<br />
Extremely thick both dorsal & ventral to optic nerve
Monochromatic<br />
loss <strong>of</strong> S opsin<br />
Ganglion cells!!<br />
Very large but sparce<br />
Pinniped<br />
Ganglion cells!!<br />
Dog
Sclera<br />
• Thick<br />
– Near limbus<br />
– Near optic nerve<br />
• Thin<br />
– At equator<br />
Vascular Plexus<br />
Similar to <strong>the</strong> vascular plexus<br />
seen in cetaceans?
Vascular Plexus<br />
Similar to <strong>the</strong> vascular plexus seen in<br />
cetaceans?
References<br />
• Miller S., Coltiz C., Dubielzig R. (2010) <strong>Anatomy</strong> <strong>of</strong> <strong>the</strong> <strong>California</strong> sea lion<br />
<strong>globe</strong>. <strong>globe</strong>.<br />
Veterinary Ophthalmology supplement 1: 63‐71. 63 71.<br />
• Ya Supin, Supin,<br />
Alexander, et al. The Sensory Physiology <strong>of</strong> Aquatic Mammals.<br />
Boston, Kluwer Academic Publishers, 2001. (pp 239‐264) 239 264)<br />
• Mass A. & Ya Supin A. (2007) Adaptive Features <strong>of</strong> Aquatic Mammals’ Mammals<br />
Eye. The Anatomical Record 290:701‐715.<br />
290:701 715.<br />
• Peichl L. et al. (2001) For Whales and <strong>Sea</strong>ls <strong>the</strong> Ocean is Not Blue: A<br />
Visual Pigment Loss in Marine Mammals. European Journal <strong>of</strong><br />
Neuroscience 13: 1520‐1528. 1520 1528.
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