Sulfotransferase that utilizes 3'-phospho-5'-adenylyl sulfate (PAPS) as sulfonate donor to catalyze the transfer of sulfate to position 6 of non-reducing N-acetylglucosamine (GlcNAc) residues of keratan. Mediates sulfation of keratan in cornea. Keratan sulfate plays a central role in maintaining corneal transparency. Acts on the non-reducing terminal GlcNAc of short and long carbohydrate substrates that have poly-N-acetyllactosamine structures. May also have activity toward O-linked sugars of mucin-type acceptors. Golgi membrane, early secretory pathway. Expressed in cornea. In human, there are 2 related proteins, CHST5 and CHST6, the latter mediating sulfation of keratan in cornea. In mouse however, there is no CHST6 protein, CHST5 functioning as a corneal keratan sulfotransferase and mediates such function. Belongs to the sulfotransferase 1 family. Gal/GlcNAc/GalNAc subfamily.