The purpose of this study is to determine whether 24-hour fluctuation of intraocular pressure (IOP) is associated with central corneal thickness (CCT) in subjects with ocular hypertension or open angle glaucoma and in age-matched controls. Also to evaluate whether mean IOP reduction as a response to latanoprost (0.005% Xalatan) is associated with CCT, after a 4-weeks period of treatment.

Also, to evaluate whether 24-hour fluctuation of IOP is associated with corneal hysteresis (CH) measured by Ocular Response Analyzer (ORA).

Inclusion Criteria:

Males and females >50 years old with:

• Primary Open-Angle Glaucoma newly diagnosed or with anti-glaucoma medical treatment < =12 weeks
• Pseudoexfoliative Glaucoma newly diagnosed or with anti-glaucoma medical treatment <= 12 weeks
• Ocular Hypertensives newly diagnosed or with anti-glaucoma medical treatment <= 12 weeks
• Age-matched controls
• IOP>=22mmHg at the eligibility visit for glaucoma patients and ocular hypertensives

Exclusion Criteria:

For Eye

• Use of any ophthalmic medication (drops) during the study (except for natural tears)
• Inflammation of any aetiology
• Previous eye surgery or laser
• Corneal abnormalities (oedema, dystrophies etc) For Subjects
• Systemic diseases which affect the cornea (such as autoimmune diseases)
• Inability to participate due to advanced age or serious illness
• Mean IOP>36mmHg in either eye at the eligibility visit.
• Subjects who cannot safety discontinue use of all IOP-lowering medication(s) for washout
• Subjects with severe central visual field loss in either eye. Severe central visual field loss is defined as sensitivity <=10dB in at least 2 of the 4 visual field test points closest to the point of fixation
• Other types of glaucoma (such as angle-closure glaucoma and secondary glaucomas)