This study was designed to evaluate efficacy of a natural eye drop made of Plantago ovata mucilage versus placebo to improve dry eye symptoms. In a Randomized, double-masked, placebo-controlled clinical trial, sixty dry eye patients with ocular symptom and total OSDI score≥12 were randomly assigned to receive either a natural ophthalmic drop, made of Plantago ovata mucilage or placebo 4 times a...