How do amhetamines affect glaucoma?

Be careful. There are 2 types of glaucoma: open aangle and narrow (closed) angle. Narrow angle is less common and is caused by the iris (color of the eye) blocking the eye's natural drain. Certain medications can force the iris to further block the drain, increasing eye pressure and worsening the glaucoma. For this reason, it is vital that you tell your eye doctor all the medications/drugs that you take.
Increase pressure. This class of drugs can exacerbate glaucoma by causing the pupils to dilate and narrowing the drainage angles inside the eyes. This narrowing can potentially lead to increased eye pressure and subsequent glaucomatous damage. More serious in narrow-angle type glaucoma.