The effect of pH and osmolarity on the ability of tolerate artificial tears.

Many patients with keratitis sicca complain that the commercially available artificial tears burn when they are instilled and fail to relieve their distressing symptoms. We examined the effects of altering both the pH and osmolarity of hydroxypropyl methylcellulose tear substitute on the tolerance of 15 patients with varying degrees of keratitis sicca. Approximately equal numbers of patients selected the neutral hypotonic tear preparations and the isotonic or near-isotonic alkaline tear substitutes. The isotonic alkaline tear preparation was preferred by the majority of our patients with moderate or severe dry eyes. A commercially available alkaline tear substitute is needed.