The present invention relates to artificial tear formulations and ophthalmic formulations suitable for drug delivery. The formulations comprise galactomannans such as guar or hydroxypropyl guar and a borate source such as boric acid. The formulations further comprise a cis-diol such as sorbitol that interferes with the cross-linking of galactomannan and borate. Optionally, the formulations are substantially free of divalent cations.