According to the American Academy of Ophthalmology's Preferred Practice Pattern on Primary Open Angle Glaucoma, patients should wait five minutes between administering topical drops for intra-ocular pressure reduction.

To date, no study has shown the efficacy of this waiting period. In this study, we aim to establish the clinical significance of keeping a time interval between glaucoma medications.

Glaucoma is a chronic disease in which constant damage to retinal nerve fibers. In most cases the damage is caused by increased intra-ocular pressure (IOP). Without treatment, this disease can cause irreversible decrease in visual fields until the patient eventually becomes blind.

The first line of treatment include topical eye-drops aimed at reducing IOP. Many patients require more than one drug type.

According to the American Academy of Ophthalmology's Preferred Practice Pattern on Primary Open Angle Glaucoma, patients who are using two or more drop types, should wait five minutes after the first drop, before administering the second type..

To date, no study has shown the efficacy of this waiting period. In this study, we aim to establish the clinical significance of keeping a time interval between glaucoma medications.

The study composes of two separate parts:

Part 1 - The aim of this part will be to estimate the short term effect on IOP reduction. Healthy subjects willing to participate voluntarily, will be given two IOP reduction drugs (Tilopitc and Alphagan) at different intervals in each eye. After which they will undergo repeated IOP measurements over a course of 7 hours.

Part 2 - The aim of this part will be to estimate the short term effect on IOP reduction. Glaucoma patients treated in the glaucoma clinic at Sheba-Medical center who are taking two different types of IOP reduction drugs in both eyes, will be recruited. The patients will be asked to keep a constant 5 minute interval between drops in one eye and to instill the drops in the other eye with no waiting time. After one month the patients will return for a revaluation of IOP and then be asked to switch the eyes so that the eye in which the interval was not kept will now be the one in which the drop will be put after 5 minute interval.

Inclusion Criteria:

Short duration group

• Healthy individuals with negative past ocular history
• able to give consent

Long duration group:

• Diagnosed with primary open angle glaucoma and being treated with two types of IOP reduction drops.
• No other medical ocular history.
• No cognitive disfunction
• able to give consent
• No known arrhythmia

Exclusion Criteria (Both groups):

• Corneal disease preventing from visualization of the angle
• Closed angle
• Pregnant women
• Previous ocular surgery (including cataract or refractive surgery)
• Known allergy to ocular drops used in this study (e.g. brimonidine, timolol)
• History of asthma or arrhythmia