A Bit On The Eye

The Weddell seal has a large number of well developed rods (photoreceptor cells that are sensitive to low light), and a well developed tapetum lucidum (a layer of tissue found in many vertebrates located in or behind the retina that reflects and refracts light back through the retina intensifying the light to photoreceptor cells). The tapetum lucidum is the cause of the eyeshine phenomenon in photographs. These adaptations allow the Weddell seal to see well in low light conditions like at depth or under sea-ice, but sacrifice high quality focus to a degree. For a little more on the Weddell seal eye you can check out this abstract (or the paper for you lucky folks who have access).

You can get more interesting Weddell seal information from Weddell Seal Science.
Weddell seal images obtained under NMFS Permit No. 1032-1917