Is sclera a word in the Scrabble Dictionary

Yes, sclera is playable

...and is worth 10 points.

Found in the following dictionaries

Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)

"Sclera" Definition

noun

The tough white fibrous outer envelope of tissue covering all of the eyeball except the cornea. Also called sclerotic, sclerotic coat.
The dense fibrous opaque white outer coat enclosing the eyeball except the part covered by the cornea .