The objective of this study was to investigate the improving effect of corneal disorder in primary open-angle glaucoma and ocular hypertension patients, when switched from the 0.005% latanoprost ophthalmic solution (one drop at a time, once daily) to the 0.0015% tafluprost ophthalmic solution (one drop at a time, once daily). Efficacy also was investigated.

Inclusion Criteria:

• Age of 20 years or older and those who was provided informed consent.
• POAG or OH patients whose IOP did not exceed 22 mmHg at Visit 0.
• Patients had treated with prostaglandin ophthalmic solution (0.005% Latanoprost) for at least 3 months before enrollment.
• Patients who had corneal disorders due to the PG usage. (At least one eye had a score above 1 on the NEI scale)
• If only one eye was eligible, it was evaluated. When both eyes were eligible, then the eye with a higher NEI score was selected for evaluation.
• Outpatients who visited the clinic on the designated day as instructed by the physician.

Exclusion Criteria:

• Those with severe visual field disorder (Mean deviation of 15 dB or worse).
• Those who received corneal refractive surgery.
• Those with a history of ocular surgeries (such as corneal refractive surgery, intraocular surgery including ocular laser treatment which affected the patient's ocular surface condition) within 3 months prior to enrollment.
• Any corneal abnormality or other condition preventing IOP measurement.
• Those who used artificial tears to relieve dry eye symptoms.
• Those with severe dry eye, ocular allergy, ocular infection or ocular inflammation which considered affect interpretation of the results of the study. Those who used systemic or ophthalmic steroids (excluding topical skin steroidal ointment) and anti-glaucoma agents other than prostaglandin ophthalmic solution.
• Female patients who were pregnant, nursing or lactating.
• Those with a history of drug allergy (hypersensitivity) to the drugs to be used during the study period (anesthetic ophthalmic solution, fluorescein, etc.) or similar drugs to the study medication.
• Those who wore contact lenses during the study period.
• Those who had participation in another clinical trial involving an investigational drug/device, or participation in such a trial within the last 30 days.