A 61-year-old man is noted to have increased intraocular pressure on a routine eye examination. The visual acuity is normal in both eyes. The dilated eye examination reveals no evidence of optic nerve damage. Visual field testing shows mild loss of peripheral vision. He is diagnosed with primary open-angle glaucoma and is started on pilocarpine ophthalmic drops.
1) What is the action of pilocarpine on the muscles of the iris and cilia?
2) What receptor mediates this action?
3) Is pilocarpine the appropriate first-line drug for treatment of primary open-angle glaucoma?