This motor response occurs within minutes of drinking coffee and can last for up to 90 minutes. There is no gender difference in the effect that coffee has on motor activity (Rao et al, 1998), but it may not be related to caffeine.
Dilation of the pupil in an eye with the synechia can cause the pupil to take an irregular, non-circular shape (Dyscoria) as shown in the photograph. If the pupil can be fully dilated during the treatment of iritis, the prognosis for recovery from synechia is good. This is a treatable status. To subdue the inflammation, use topical corticosteroids.
In other words, contraction of radial smooth muscle causes dilation of the pupil. This explains the autonomic actions: 1  Increased release of acetylcholine by the parasympathetic nervous system causes contraction of circular smooth muscle. 2  This makes the pupil (the dark hole) smaller.he pupil is contricted or dilated by the contraction of smooth muscle in the iris. There are two types. One type is arranged in the circle near the pupil. When a circle of muscle contracts, the circle becomes smaller. Thus contraction of the circular muscle causes constriction of the pupil.