A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.
Acetylcholine. Acetylcholine (ACh) is the transmitter released by the preganglionic nerve terminals of both the sympathetic and the parasympathetic divisions (Fig 6.2). The synapse at those sites utilizes a nicotinic receptor similar in structure to the receptor at the neuromuscular junction.
Most postganglionic sympathetic fibers release norepinephrine (adrenaline ) and thus are considered to function by adrenergic transmission . A few postganglionic sympathetic fibers , such as those that innervate the sweat glands , release acetylcholine .