The objective of this study is to evaluate the effect on corneal endothelial cell density changes when ISV-403 is administered for five (5) days compared to no drug treatment, in healthy subjects.

Inclusion Criteria:

• Must have pin-holed Snellen visual acuity equal to or better than 20/40, in both eyes
• Must be in good health (no current or past relevant medical/ocular history) based on the judgment of the Investigator
• Must be willing to discontinue contact lens wear for the duration of the study

Exclusion Criteria:

• Known hypersensitivity to fourth generation fluoroquinolone (SS734) or to any of the ingredients in the study medication Investigator determines could interfere with the study
• History of extended or continuous wear contact lens use other than silicone hydrogels
• History of intraocular surgery
• Any topical ophthalmic medication, including tear substitutes, that cannot be discontinued during the study
• Participation in an ophthalmic drug or device research study within the 30 days prior to entry in this study