The purpose of this study is to confirm the safety and efficacy of diquafosol tetrasodium ophthalmic solution, 2% vs. placebo, in subjects with dry eye disease.

Inclusion Criteria:

• Have best corrected visual acuity in both eyes of at least +0.7 or better
• Central corneal staining of 3 on the NEI scale
• If female, are non-pregnant or non-lactating
• Have a history of dry eye disease in both eyes
• Have normal lid anatomy

Exclusion Criteria:

• Unable to withhold the use of contact lenses during the study or 2 weeks prior to the study
• Have had ocular surface surgery within the past year
• Are considered legally blind in one eye
• Have a serious medical condition which could confound study assessments