N-acetyl glucosamine (GlcNAc) transferase that catalyzes the transfer of GlcNAc via a beta1->3 linkage from UDP-GlcNAc to the non-reducing terminal galactose (Gal) in the linearly growing chain of N- and O-linked keratan sulfate proteoglycans. Cooperates with B4GALT4 galactosyltransferase and CHST6 and CHST1 sulfotransferases to construct and elongate mono- and disulfated disaccharide units [->3Galbeta1->4(6-sulfoGlcNAcbeta)1->] and [->3(6-sulfoGalbeta)1->4(6-sulfoGlcNAcbeta)1->] within keratan sulfate polymer (PubMed:14706853, PubMed:17690104). Involved in biosynthesis of N-linked keratan sulfate proteoglycans in cornea, with an impact on proteoglycan fibril organization and corneal transparency (PubMed:17690104) (By similarity). May play a role in the maintenance of tissue architecture by suppressing cellular motility and invasion (By similarity). Protein modification; protein glycosylation. Expressed in corneal epithelial cells. Belongs to the glycosyltransferase 31 family. Beta 1,3-N-acetylglucosaminyltransferase 7