In this study we will explore the combined effect of Brimonidine and Timolol 0.5% (Combigan) eye drops on pupil dilation. It is a well studied phenoma that Brimonidine and a miotic effect on the pupil, however the combined effect of alpha agonist and beta blocker has not been studied.

In this study we will explore the combined effect of Brimonidine and Timolol 0.5% (Combigan) eye drops on pupil dilation. It is a well studied phenoma that Brimonidine and a miotic effect on the pupil, however the combined effect of alpha agonist and beta blocker has not been studied.

The study subjects will be examined twice, two weeks apart. On the first exam the subject will receive Combigan eye drop to the right eye and a Brimonidine drop to the left eye. The effect on pupil size before and 30 minutes, 60 minutes, 240 minutes, and 300 minutes after instillation of eyedrops. On the second exam the subject will receive Timolol (0.5%) eye drop to the right eye and a Brimonidine drop to the left eye. The effect on pupil size before and 30 minutes, 60 minutes, 240 minutes, and 300 minutes after instillation of eyedrops.

Inclusion Criteria:

• Healthy adults subjects with no ocular pathology
• Non pregnant women
• Normal pupil response

Exclusion Criteria:

• Chronic topical treatment
• Systemic medication affecting autonomic nerve system
• History of intra-ocular surgery
• Irregular pupil
• History of ocular neurological or severe cardio-vascular disease