It is a phase III, multi-center, randomized, single-blind (to evaluator), parallel, and positive-controlled clinical trial evaluating the efficacy and safety of OPC-1085EL in the treatment of primary open angle glaucoma or ocular hypertension in Chinese subjects. It is planned that 240 subjects (120 in each group) will be randomly assigned to receive OPC-1085EL or 0.005% latanoprost ophthalmic solution (latanoprost) at a ratio of 1:1.

The trial includes 2 period:

1. Screening period: 4 weeks. For subjects entering the screening period, 0.005% latanoprost will be administered for 4 consecutive weeks, one drop for each eye, once per day.
2. Evaluation period: 8 weeks. Subjects who are eligible are randomly assigned to the OPC-1085EL group or 0.005% latanoprost group at a ratio of 1:1, one drop for each eye, once per day.

Inclusion Criteria:

1. Gender: Unlimited

2. Hospitalization status: Outpatients

3. Age: 20-80 years old

4. Subjects with both eyes diagnosed as primary open angle glaucoma or ocular hypertension.

   [At the end of the screening period]

5. IOP: After 4 weeks treatment with 0.005% latanoprost, the unilateral eye with a pre-dose IOP from 18 mmHg to <30 mmHg, and IOP <30 mmHg in the contralateral eye.

Exclusion Criteria:

1. Subjects with a best-corrected visual acuity ≤ 0.2.
2. Subject with any secondary glaucoma such as exfoliative or pigmented glaucoma.
3. Subjects who cannot stop using contact lenses during the trial.
4. Subjects who are judged by investigators to be at risk when receiving carteolol hydrochloride or 0.005% latanoprost as monotherapy.
5. Subjects who are allergic to any ingredients in carteolol or latanoprost.