Hyaluronic acid, a natural polymer, helps to maintain ocular surface hydration and can already be found in several artificial tears recommended to alleviate symptoms of dry eye. A recent hyaluronate modification involves zinc-hyaluronate complex formation by adding zinc-chloride to an aqueous sodium-hyaluronate resulting in a very stable molecular structure, which functions as both a mechanical barrier and a biocompatible film on the ocular surface. Apart from its beneficial elastoviscous characteristics, previous results indicate that hyaluronate can also reduce the excitability of the peripheral nociceptor endings underlying pain. Although hyaluronate is widely used in artificial tears to improve tear film stability, its effect on ocular surface sensitivity was not evaluated in patients with dry eye. The aim of this study is to investigate the characteristics of ocular surface sensations and corneal sensitivity in dry eye patients before and after long-term tear supplementation with zinc-hyaluronate.

Inclusion Criteria:

• Patients who had been diagnosed as having dry eye symptoms for at least 3 months, with an OSDI score of ≥13 evaluated by the questionnaire of Ocular Surface Disease Index (OSDI)

Exclusion Criteria:

• Subjects with ophthalmic conditions other than dry eye or systemic disease including blepharitis, meibomitis, lid abnormalities as well as contact lens wearers